seabird migration in the canadian northwest atlantic ocean: moulting locations and movement patterns...

Seabird migration in the Canadian northwestAtlantic Ocean: moulting locations and movementpatterns of immature birds

F. Huettmann and A.W. Diamond

Abstract: All seabirds in the northwest Atlantic Ocean migrate, but timing and routes are not well understood. Weevaluate existing knowledge on seabird migration with data from the Programme intégré de recherches sur les oiseauxpélagiques (PIROP) data base, using observations of immature and moulting seabirds to track migration of the follow-ing species: Northern Fulmar (Fulmarus glacialis), Greater Shearwater (Puffinus gravis), Northern Gannet (Morusbassanus), Herring Gull (Larus argentatus), Iceland Gull (Larus glaucoides), Glaucous Gull (Larus hyperboreus), GreatBlack-backed Gull (Larus marinus), Black-legged Kittiwake (Rissa tridactyla), and Thick-billed Murre (Uria lomvia).The distributions of immature and moulting birds show strong seasonal patterns in the northwest Atlantic, and newtransition zones and clear biological borderlines for seabird distribution were found. New data on timing and locationof moulting Thick-billed Murres are presented. The southern Labrador Banks and Grand Banks (Thick-billed Murre,Northern Fulmar) and southeast Newfoundland and Georges Bank (Greater Shearwater) were identified as moultinggrounds. In terms of marine conservation the following areas seem to be important for part of the life cycle of the spe-cies named: western Greenland, Cape Cod, Grand Banks, Labrador Banks, southwest Newfoundland, and the GrandManan area.

Résumé: Tous les oiseaux de rivage de l’Atlantique du nord-ouest sont des migrateurs mais leurs routes de migrationet le moment qu’ils choisissent pour migrer ne sont pas parfaitement compris. Nous évaluons nos connaissances actuel-les sur la migration des oiseaux de rivage en utilisant des données empruntées à PIROP (Programme intégré de recher-ches sur les oiseaux pélagiques) et les résultats d’observations d’oiseaux migrateurs immatures ou en mue, dans le butde suivre la migration des espèces suivantes : le Fulmar boréal (Fulmarus glacialis), le Puffin majeur (Puffinus gravis),le Fou de Bassan (Morus bassanus), le Goéland argenté (Larus argentatus), le Goéland arctique (Larus glaucoides), leGoéland bourgmestre (Larus hyperboreus), le Goéland marin (Larus marinus), la Mouette tridactyle (Rissa tridactyla)et le Guillemot de Brünnich (Uria lomvia). La répartition des oiseaux immatures et des oiseaux en mue suivent despatterns saisonniers bien définis dans l’Atlantique du nord-ouest et de nouvelles zones de transition et limites territoria-les biologiques ont été identifiées. De nouvelles données sur le moment et le site de la mue du Guillemot de Brünnichsont présentées. Les bancs du sud du Labrador et les Grands bancs (Guillemot de Brünnich, Fulmar boréal), le banc dusud-est de Terre Neuve et le banc Georges (Puffin majeur) sont reconnus comme sites de mue. Pour la conservation dela vie marine, les régions suivantes semblent jouer un rôle important durant au moins une partie du cycle des espècescitées : l’ouest du Groenland, le cap Cod, les Grands bancs, les bancs du Labrador, le sud-ouest de Terre-Neuve et larégion du Grand Manan.

[Traduit par la Rédaction] 647 Huettmann and Diamond

Introduction

All seabirds in the North Atlantic Ocean migrate.Normally, their migration covers many hundreds of kilo-metres and is affected by foraging, breeding, moulting, flightenergetics, and travel between winter and summer grounds(Ashmole 1971; Pennycuick 1987a, 1987b; Furness andBurger 1988; Newton and Dale 1996). The migration pat-terns and concentration areas of seabirds in the northwest

Atlantic are not well known; they are difficult to investigatein the field and most knowledge of migration flyways androutes is based on rough descriptions and arrows on maps(Tuck 1961; Brown 1983; Powers 1983; Braune 1989;Alerstam 1993; Stenhouse and Montevecchi 1996). Rela-tively narrow migration corridors can be found along theshelf edge (F. Huettmann, unpublished data, Voous andWattel 1963), and seabirds are believed to follow fish migra-tion routes (McCleave et al. 1984) and currents (Stenhouseand Montevechi 1996; Gaston and Jones 1998). Normally,the only quantitative information on seasonal seabird migra-tion stems from recoveries of birds banded in colonies dur-ing summer (Gaston 1982; Brewer et al. 2000). Banded-birdrecoveries are biased by very specific mortality causes, suchas hunting, fishing, or oil spills, making analyses and gener-alizations of band recoveries difficult (Salomonsen 1967a;Baird 1994; Chapdelaine 1997; Brewer et al. 2000). Furthermethods of investigating seabird migration include counts

Can. J. Zool.78: 624–647 (2000) © 2000 NRC Canada

624

Received January 8, 1999. Accepted November 12, 1999.

F. Huettmann1 and A.W. Diamond. Atlantic CooperativeWildlife Ecology Research Network (ACWERN), Universityof New Brunswick, P.O. Box 45111, Fredericton,NB E3B 6E1, Canada.

1Author to whom all correspondence should be addressed(e-mail: [email protected]).

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made from the coast (for example, Christmas Bird Countsin Root 1988) or offshore islands (for Sable Island seeMcLaren 1981), oil rigs, and stepping stones for seabird mi-gration (e.g., Georges Bank for fall and spring migration;Powers and Brown 1987, cited in Backus and Bourne 1987).Time-referenced oil spills can also produce useful data, as-suming that seabirds oiled out at sea wash ashore (Brownand Johnson 1981; McLaren 1981). Satellite transmittersprobably offer the best data on movement patterns, but todate have been applied only to larger seabirds and not in thearea covered by the Programme intégré de recherches sur lesoiseaux pélagiques (PIROP; see Materials and methods)(Jouventin and Weimerskirch 1990; Myers et al. 1998; butsee Falk and Moeller 1995).

Investigating the location of seabirds observed in moultcan also help in tracking seabird movement. But the moultof seabirds presents a challenge, since moulting patterns ofbirds at sea are poorly known, and moulting seabirds are dif-ficult to identify at sea (Harrison 1983; Gaston and Jones1998). Moulting during the migration process is well knownin other water birds, but has not been addressed in seabirds.During moult some seabirds are vulnerable, since they can-not fly; their moulting locations therefore constitute key ar-eas for conservation of the full life cycle. Because ofincreasing threats to the marine ecosystem off Eastern Can-ada (Wilson and Addison 1984; Nettleship 1991), migrationcorridors and other sensitive areas, such as moultinggrounds, need to be identified (Brown and Nettleship 1984a;Nettleship 1991).

Extensive distribution data, combined with careful analy-sis of band recoveries, offer an alternative source of evi-dence of movement patterns to supplement those currentlyused. Based on the PIROP data base (Brown et al. 1975;Brown 1986; Huettmann and Lock 1997), this paper pres-ents findings from counts and observations of seabirds atsea, which allow for tracking migration by age-class ormoulting status. The following species were selected on thebasis of a sample of at least 80 observations: Northern Ful-mar (Fulmarus glacialis), Greater Shearwater (Puffinus gra-vis), Northern Gannet (Morus bassanus), Herring Gull(Larus argentatus), Iceland Gull (Larus glaucoides), Glau-cous Gull (Larus hyperboreus), Great Black-backed Gull(Larus marinus), Black-legged Kittiwake (Rissa tridactyla),and Thick-billed Murre (Uria lomvia). We compare unpub-lished PIROP data with existing knowledge, and we map andidentify areas of relevance to these seabirds during their mi-gration and moulting seasons. The origin of individual adultbirds cannot be determined visually (however, for NorthernFulmars see Brown 1973, 1988), but analysis of the tempo-ral patterns of distribution of selected seabirds with a dis-tinctive immature plumage, or obviously in moult, allows usto identify important marine areas and flyways and deter-mine timing of migration. PIROP records are of birds seenfrom a distance and at sea, so in our study we refer to imma-ture birds as those that are not in a mature plumage, juvenilebirds as those within 1 year of fledging (except Thick-billedMurres (Gaston 1984); see later), and adults as birds in basicor definitive plumage (sensu Humphrey and Parkes 1959).Timing of moult is detectable from observations of birds inflight with missing primaries or secondaries, and so involvesonly moult of flight feathers, not body feathers.

Materials and methods

The PIROP scheme is a project for acquiring, storing, and re-trieving observations of seabirds at sea, spanning 1966–1992.PIROP was established in 1965 by the Canadian Wildlife Serviceat the Bedford Institute of Oceanography in Dartmouth, Nova Sco-tia. It covers unlimited-width transects divided into 10-min units ofnumbers of seabirds at sea from “vessels of opportunity.” Thestudy area and places identified in the text are shown in Fig. 1.Figure 2 shows all locations where PIROP counts were carried outbetween 1966 and 1992. Most observations were made by R.G.B.Brown, but other observers contributed to this data set, which com-prises 223 942 observations, or 73 628 individual 10-min transects,during 26 years. The data vary in amount through the months andyears, but most stem from surveys made during the summermonths in the late 1970s and early 1980s. Detailed descriptions ofPIROP can be found in Lock et al. (1997), Brown et al. (1975),Brown (1986), Diamond et al. (1986, 1993), Lock et al. (1994),and Huettmann and Lock (1997). Because of the large study area,PIROP data stem from vessels of opportunity and show uneven ef-fort, especially for some parts of the study area, such as deep wa-ters. Diamond et al. (1986) documented some effects of observer’sheight, sea state, ship speed, and visibility on counts, and devel-oped correction factors to convert unlimited-width counts into den-sities. Here we are concerned with timing and distribution ofimmature and moulting birds, not with absolute numbers, so weuse raw data and no correction factors. We provide maps of thedistribution of observations by season (prebreeding, breeding, post-breeding, winter) as described in Diamond et al. (1993). We havearranged the figures and tables to allow for species comparisonsby subject (moulting and immature birds).

Locations of juvenilesThe full PIROP data set was queried with FoxPro (Siegel 1994;

Huettmann and Lock 1997), using the age column (Lock et al.1997). Adequate sample sizes (>80 observations) were found forThick-billed Murre, Iceland Gull, Northern Fulmar, Northern Gan-net, Black-legged Kittiwake, Herring Gull, Glaucous Gull, andGreat Black-backed Gull (see Fig. 3 for sample sizes for each spe-cies). For the systematics of gull species we have followed the cur-rently accepted taxonomy of the American Ornithologists’ Unionchecklist. The latitudes of observations of immature birds of eachspecies per month were analyzed with Standard Query Language(SQL) queries in Visual FoxPro (Siegel 1994) using the mean,maximum, minimum, and standard deviation. To compare distribu-tions of immature and adult birds, all PIROP observations of eachspecies were also extracted. The selected data sets were importedinto the SPANS Geographic Information System (INTERACTYDAC 1992, 1993, 1995) and then visualized as maps.

Locations of moulting birdsThe PIROP data set was again queried with FoxPro, this time

using the moult column (Lock et al. 1997). Sample sizes were ade-quate for Thick-billed Murre, Greater Shearwater, and NorthernFulmar. The latitudes for each observation of species in moult permonth were analyzed with SQL queries in Visual FoxPro (Siegel1994) using the mean, maximum, minimum, and standard devia-tion. To allow comparison of distributions of moulting and non-moulting birds, all observations for each species were also extracted.

Results

Northern FulmarThis species was observed in the study area year-round.

Moulting fulmars were observed only in March and fromMay through October, with a very marked peak in July

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626 Can. J. Zool. Vol. 78, 2000

Fig. 1. The study area, with locations referred to in the text.



(Fig. 4) on the Labrador Banks and Newfoundland Banks(Fig. 13). Colour morphs of birds observed in moult show apeak for light morphs in May; dark birds in moult were onlyobserved in very low numbers in March, July, and August(Table 1). Moulting birds were widely distributed in August:Lancaster Sound, Frobisher Bay, Labrador, and GeorgesBank (Figs. 8 and 13). Immatures cannot be distinguishedfrom adults in this species.

Greater ShearwaterMoulting Greater Shearwaters were observed from May

through September (Fig. 4). The proportion of moulting birdsincreased in May, peaked in June, and decreased throughAugust and September. In May shearwaters avoided thecoast (Fig. 13). In June, distribution was concentrated southof Newfoundland and on the Scotian Shelf. By July birdshad appeared on the Labrador Shelf; in August most were onthe Scotian Shelf and in the Gulf of Maine (Figs. 8 and 13).Shearwaters occurred in large numbers in the Bay of Fundy(Brown 1988; Huettmann and Diamond 1998; L. Murison,unpublished data for Grand Manan; C. Haycock, unpub-lished data for Brier Island), though they are rarely seenmoulting primary feathers there (F. Huettmann and A.W. Di-amond, unpublished data). The numbers also peaked laterthere than in south Newfoundland, and birds can be found inthe Bay of Fundy until the end of November (F. Huettmannand A.W. Diamond, unpublished data). Immatures cannot bedistinguished from adults in this species.

Northern GannetGannets do not develop adult plumage until they are 4

years old (Harrison 1983). Our data do not differentiatethese four age-classes, which differ in the amount of whitein the plumage (least amount in juveniles, complete in adults).Figure 3 shows that the proportion of immature birds peakedin October at 55%, and >20% of observations were made be-tween May and November. The distribution of immaturegannets shows clear patterns in seasonality and movements(Figs. 6 and 12). Observations in winter and during theprebreeding season were almost all made south of NovaScotia and close to the coast, e.g., Cape Cod, New York City,and Washington, D.C. In summer, observations were clumpedaround the six major gannet breeding colonies (BonaventureIsland, off Newfoundland, and Labrador) (Nettleship 1980;Cairns et al. 1989; Lock et al. 1994, Brewer et al. 2000),with areas of high concentration at Îles de la Madeleine(where there is a colony) and the Strait of Belle Isle (wherethere is not). High gannet concentrations in other areas (lowerBay of Fundy and Georges Bank) are likely of nonbreedingbirds, which are not tied to colonies. Only seven observa-tions of immatures were made north of 55°N (Figs. 6 and12). After the breeding season most birds were not close tobreeding colonies. High densities of immature gannets werefound in the lower Bay of Fundy and off Cape Cod, and to alesser degree off north Nova Scotia and southeast New-foundland; some birds were found off Nova Scotia near theshelf edge (Figs. 6 and 12).

© 2000 NRC Canada


Fig. 2. Spatial effort in PIROP data for 1966–1992; dots indicate locations of seabird observations.



Herring GullIt takes at least 3 years for Herring Gulls to develop adult

plumage (Harrison 1983; Grant 1986). The proportion of im-mature birds peaked in October at 50% (Fig. 3), with an-other peak in May and June (30%). The lowest percentagewas 10% in July. In the breeding season immature HerringGulls were distributed mainly in coastal waters throughoutthe St. Lawrence region, southern Gulf of Maine, and alongthe shelf edge of the Labrador Banks (Fig. 9). Winter and

prebreeding immatures were clumped in the Cape Cod areaand to a much smaller degree in the Gulf of St. Lawrence(Fig. 5). Observations made during the breeding season ex-tended farther north but not beyond 55°N, with a few excep-tions in Hudson Bay (Fig. 5). There was a high concentra-tion of immatures during the breeding season in the St.Lawrence River, Northumberland Strait, Strait of Belle Isle,Grand Manan area, and off Cape Cod; these are all breedinggrounds. In the postbreeding season there were high concen-

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Fig. 3. Seasonal changes in the proportions of immature/juvenile Northern Gannets, Herring Gulls, Iceland Gulls, Glaucous Gulls,Great Black-backed Gulls, Black-legged Kittiwakes, and Thick-billed Murres per month in the PIROP data base (n is the total numberof observations).



trations on the northwest shoals off Newfoundland, in GrandManan, and in the Gulf of Maine.

Iceland GullsSince the immature plumage lasts 2 years (Harrison 1983;

Grant 1986), immature Iceland Gulls were observed year-round, peaking in October at 50% and again in spring at35% (Fig. 3). The lowest percentages were in July (6%) andwinter (<25%). The southward movements that occur duringwinter are reflected in Fig. 7. Wintering birds were found in

the St. Lawrence region and the Scotian Shelf, but rarelybeyond Georges Bank (Figs. 7 and 11). There was a clearconcentration of immature birds around colonies off south-west Greenland in the postbreeding season (September). Inspring (April and May), immature birds concentrated alongthe ice edges off Labarador and the southern Davis Strait.

Glaucous GullImmature Glaucous Gulls can be found throughout the

year; it takes up to 2 years for immature plumage to be lost(Harrison 1983; Grant 1986). The proportion of immaturebirds peaked in September (40%) and was lowest in August(15%) (Fig. 3). The winter distribution of immatures wasmostly far out at sea and along the shelf edge of the LabradorBanks, with a higher concentration south of the LabradorBanks, south of Greenland, and southwest of Newfoundlandin the Gulf of St. Lawrence (Fig. 11). The prebreeding dis-tribution likely reflects the location of ice edges, where im-mature Glaucous Gulls concentrate (McLaren 1982). Theprebreeding distribution of immatures was also concentratedsouth of Greenland and on the northeast Scotian Shelf. Thebreeding-season distribution included a pelagic distributionin Davis Strait and a concentration around breeding coloniesoff the west coast of Greenland. Almost no immatures werefound south of 55°N during the breeding season. The post-breeding distribution in Davis Strait is mostly offshore alongthe continental shelf.

© 2000 NRC Canada


Fig. 4. Seasonal changes in the proportions of moulting Greater Shearwaters, Northern Fulmars, and Thick-billed Murres per month inthe PIROP data base (n is the total number of observations).

Colour morph No. of sightings

March Light 3May Light 3July Light 22July Dark 1August Light 6August Dark 4September Light 1October Light 2

Table 1. Observations of Northern Fulmars inmoult, by colour morph, in the PIROP data base(74 addional observations were labeled in PIROP as“morph not determined” and are not included in thistable).



Great Black-backed GullGreat Black-backed Gulls wear immature plumage for up

to 4 years (Harrison 1983; Grant 1986). The proportion peakedin October at 40% (Fig. 3) and was lowest in July andMarch (19 and 25%). In the prebreeding season, immatureswere found mainly on the Grand Banks, in the Gulf ofMaine, and southwest of Newfoundland, and a few werefound south of Greenland (Fig. 9). The breeding-season dis-tribution of immatures was also far out at sea, including adistinct area off the southwest coast of Greenland (Fig. 5).The postbreeding season included four concentration zones:off the southwest coast of Greenland, northwest of New-foundland, the Scotian Shelf, and the whole Gulf of Maine.The winter distribution of immatures was characterized by ahigh-concentration area off Cape Cod (Fig. 5), althoughimmatures also appeared on the Grand Banks and ScotianShelf.

Black-legged KittiwakeImmatures can be distinguished in the field by the beak

colour, dark neck, and wing bands; they lose this plumagebetween August and November of the following year (Harri-son 1983; Grant 1986). Since immatures can be distin-guished for only 1 year (Baird 1994), in this species all“immatures” are juveniles. They were observed throughoutthe year, with numbers peaking in June at 40% (Fig. 3),

reaching a second peak in October (30%), and being lowestin July, December, and February. Figure 10 shows that inwinter most juveniles were found on the south LabradorBanks, with almost no observations in the Gulf of Mainearea. In the prebreeding season, juvenile birds were concen-trated on the Grand Banks, between the Grand Banks andsouth of Greenland, and to a lesser degree on the LabradorBanks. During the breeding season, juveniles were dispersedthroughout the study area, especially near the colonies onthe southern Labrador Banks and off Cape Breton, in thecentre of south Davis Strait, and off Lancaster Sound. Atthis time, juveniles were distributed offshore along the shelfedge, particularly in Lancaster Sound, south Davis Strait,and south Labrador. After the breeding season, most juve-niles were dispersed all over Davis Strait and Baffin Bay,with other concentrations on the northern shoals of New-foundland and off Lancaster Sound. The Scotian Shelf andGulf of Maine were not of major importance during thepostbreeding season, except for the Grand Manan region (F.Huettmann, unpublished data).

Thick-billed Murres“Juveniles” are identified at sea mainly by size in this spe-

cies; the plumage is almost the same as that of winter adults(Gaston and Jones 1998). Juveniles were observed only be-tween July and October (Fig. 3), probably because of the

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Fig. 5. Monthly latitudinal changes in numbers of observations (numbers below thex axis represent sample size) of immature HerringGulls (A) and Great Black-backed Gulls (B) in the PIROP data base, shown as the arithmetic mean and 95% confidence intervals.



short duration of the juvenile plumage and body size used toidentify this age-class (Harrison 1983; Gaston and Jones1998). The largest proportion of juveniles was recorded dur-ing September in Hudson Strait and Lancaster Sound, withsmaller numbers between July and October in Davis Strait inproximity to known breeding colonies (Figs. 3, 6, and 10).Almost no juvenile Thick-billed Murres were observed far-ther south than 55°N, and even in September all juvenileswere still very close to breeding colonies.

The first observations of moulting birds (prebasic moult)were made in August and September near colonies in DavisStrait. Most moulting Thick-billed Murres were observed inearly winter (November and December; Fig. 8) on the GrandBanks and Labrador Banks (Fig. 13). A few moulting birdswere also observed in February (n = 1), March (n = 2), andMay (n = 1) around Newfoundland (Fig. 8). The largest con-centration of moulting Thick-billed Murres was observed onthe south Labrador Banks and northern parts of the GrandBanks in November (Fig. 13).

Discussion

PIROP data baseFor use in bird distribution maps, Price et al. (1995) clas-

sifies three types of data: (1) positive data: known informa-tion about the abundance of a species; (2) negative data:

known information about the absence of a species; (3) “terraincognita”: no information as to whether a bird is present orabsent. The lack of regular sampling of remote areas at seacan present a considerable problem in the PIROP data, lead-ing to “terra incognita.” In the absence of any other informa-tion, the approach chosen here attempts to make the bestpossible use of the large amount of data gathered over manyyears. Qualitative data such as the moulting stage or age-class of the observed bird, normally treated as “additionalnotes” and rarely investigated, can be an important com-ponent of information, particularly when investigated in atemporal and spatial context (see also Braune 1989). Al-though the overall spatial coverage of PIROP over the 26years is impressive (Fig. 2), we had no influence on whereand when observations were made or whether observers re-ally wrote down the timing of moult and age-class of birdsobserved; so in our a posteriori investigation of the data,weused all information available.

Northern FulmarThe majority of Northern Fulmars in the North American

Atlantic Ocean breed in 11 large colonies in the EasternArctic of Canada, north of 65°N. There are additional colo-nies in Greenland, Newfoundland, and Labrador (Hatch andNettleship 1998). However, the numbers of birds breeding inEastern Canadian waters cannot account for the large num-

© 2000 NRC Canada


Fig. 6. Monthly latitudinal changes in numbers of observations (numbers below thex axis represent sample size) of immature NorthernGannets (A) and juvenile Thick-billed Murres (B) in the PIROP data base, shown as the arithmetic mean and 95% confidence intervals.



bers found throughout the year, which indicates that theNorthern Fulmar is a transatlantic migrant (Fisher 1952). Thisis well documented with band recoveries off Newfoundlandfrom young birds banded in Britain (Brewer et al. 2000;highest number of recoveries in November and May).

Powers et al. (1979) report a northward movement fromMay through July. Twenty-two recoveries of British-bandedbirds indicate a transatlantic crossing by prebreeders (Brown1968, 1973; Brewer et al. 2000). Northern Fulmars are knownto concentrate around Newfoundland in early spring; birds inthe south Labrador Sea are likely nonbreeders from Europe(Brown 1968; Powers 1983). Powers et al. (1979) mention ashort absence of Northern Fulmars from Georges Bank andthe Gulf of Maine in August; these birds are most abundantagain during October and November (Powers and Brown1987). According to Brewer et al. (2000), the southwardpostfledging dispersal is very rapid. Eight of the Greenlandrecoveries were made during September–October in waterssouth of Newfoundland.

Few fulmars are recorded in Christmas Bird Counts inmidwinter, mainly because the birds are too far offshore, andPowers (1983) shows pelagic winter observations of North-ern Fulmars no farther south than Cape Cod. Powers et al.(1979) reported large numbers at sea in the Gulf of Maine

between January and April (December through June; Schnei-der and Heinemann 1996).

Fulmars show four major colour morphs (light, very light,dark, and very dark), with continuous gradients rather thanclear divisions; each colour morph also differs in breedingdistribution (Fisher 1952; Hatch and Nettleship 1998) andmoult timing (Brown 1988), which can help in trackingmigration. Canadian Arctic breeders are predominantly thedark morph and birds breeding in Greenland and Europeare mainly the light morph (Hatch and Nettleship 1998).Stresemann and Stresemann (1966) and Hatch and Nettleship(1998) concluded that the timing of primary moult is uncer-tain, but probably starts during nesting (July); nonbreedersand failed breeders start earlier (mid-June). Hatch andNettleship (1998) stated that primary moult is finished byNovember, but Brown (1988) indicated that it may last untilFebruary. Stresemann and Stresemann (1966) and Ginn andMelville (1983) concluded that British fulmars becomeflightless during primary moult, but H.K. Lambert (cited inStresemann and Stresemann 1970) clearly indicated thatwing moult does not handicap birds in Newfoundland waterswhen in flight. Using a subset of PIROP data, Brown (1988)inferred that most moulting birds in Canadian waters arefrom the East Atlantic (light morph) and are nonbreeders

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Fig. 7. Monthly latitudinal changes in numbers of observations (numbers below thex axis represent sample size) of immature IcelandGulls (A) and immature Glaucous Gulls (B) in the PIROP data base, shown as the arithmetic mean and 95% confidence intervals.



(i.e., young birds) because their moult peaks in May, a timewhen local breeders are starting to lay eggs; however, thePIROP data show a clear peak in July, not May; Table 1shows that numbers of light-morph Northern Fulmars inmoult peak in July. Brown (1988) reported that light morphsare still quite prominent (ca. 25% of birds) in August. Pro-portions of moulting birds among Eastern Canadian (darkmorph) and Greenland or European breeders (light morph)in the Labrador Sea (i.e., nearest to breeding colonies) areprobably similar in July–August, which suggests that evenhere most birds seen are nonbreeders, or that moult is much

quicker in breeders than in nonbreeders (i.e., it may startonly in July but proceeds quickly). Hatch and Nettleship(1998) report that the Grand Banks and Labrador are ofyear-round importance, but are threatened by exploitation ofthe oil fields at Hibernia, Ben Nevis, and Terra Nova.

The sharp peak in moult during July suggest that mostmoulting birds in Canadian waters are either nonbreeders orfailed breeders, regardless of whether they are from Canada,Greenland, or Europe. This supports Brown’s (1988) sugges-tion that during the breeding season, the Labrador Banksserve as an international moulting ground for nonbreeding

© 2000 NRC Canada


Fig. 8. Monthly latitudinal changes in numbers of observations (numbers below thex axis represent sample size) of moulting Thick-billed Murres (A), moulting Northern Fulmars (B), and moulting Greater Shearwaters (C) in the PIROP data base, shown as the arith-metic mean and 95% confidence intervals.



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fulmars from the North Atlantic Ocean. However, our datado not indicate a major peak in numbers of moulting birds inMay on the Scotian Shelf, as outlined in Brown (1988)(Figs. 8 and 13).

Greater ShearwaterMost shearwaters in the area are either Greater Shear-

waters or Sooty Shearwaters (Puffinus griseus) in ratios thatrange from 7:1 (Stresemann and Stresemann 1970; GrandBanks) to 10:1 Greater Shearwaters : Sooty Shearwaters (F.Huettmann, unpublished data for the Bay of Fundy). Rees(1964) indicates that the proportion of Sooty Shearwaters in-creases with latitude. Off Sable Island, McLaren (1981) re-ported a ratio of 3:1 Greater Shearwaters : Sooty Shearwatersin early summer, but changing to 30:1 later on. GreaterShearwaters have a transequatorial migration and breed inthe southern hemisphere (Woods 1970; Warham 1990), soonly adults have been banded in Canada (Brewer et al. 2000).Virtually the whole population of Greater Shearwaters spendsthe southern hemisphere winter every year (for banding andrecoveries in North Atlantic waters see Brewer et al. 2000)in the eutrophic waters of the North Atlantic north of the

Gulf Stream (Voous and Wattel 1963), where they moult(Salomonsen 1967b; Brown 1988). Migration and moultingof Greater Shearwaters in Canadian waters are not com-pletely described.

At the end of the southern summer, in mid-April, adultGreater Shearwaters leave their colonies, head quickly north-west across the mid-Atlantic doldrums off South America ina narrow migration flyway (Voous and Wattel 1963), andreach the Gulf of Maine and Canadian waters in late May orJune (Wynne-Edwards 1935; Rowan 1952; Salomonsen 1967b;Powers et al. 1979; Brown 1988); Hagen (1952) reportssummer band recoveries off Newfoundland and (western)Greenland from birds banded at the breeding colonies(Tristan Da Cunha) and Dennis (1981) reports that a birdbanded in the Bay of Fundy was recovered near the Isles ofScilly in the U.K. Palmer (1962) mentions that some adultbirds migrate to South Africa after breeding (for January seeVoous and Wattel 1963), and that prebreeding birds leave thecolonies earlier than adults. Migration time for the approxi-mately 9000 km to Canadian waters is believed to be35 days (Stresemann and Stresemann 1970), and migrantsenter Canadian waters in waves (Stresemann and Stresemann

© 2000 NRC Canada

636 Can. J. Zool. Vol. 78, 2000

Fig. 11. Observations of immature Iceland Gulls (A) and Glaucous Gulls (B) in the PIROP data base; shaded circles indicate winter,shaded crosses the postbreeding season, shaded circles the prebreeding season, and solid squares the breeding season.



© 2000 NRC Canada


Fig. 12. Observations of immature Northern Gannets in the breeding season (shaded circles) and postbreeding season (solid circles)(A) and in the winter (shaded squares) and the prebreeding season (B) from the PIROP data base.



© 2000 NRC Canada

638 Can. J. Zool. Vol. 78, 2000

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1970; Brown 1988). Greater Shearwaters stay away from thecoast in late May and early June, but move closer to shore insouth Newfoundland when capelin spawn (Carscadden 1984,cited in Brown 1988; Brown and Nettleship 1984b). Once inCanadian waters, Greater Shearwaters spread out up to 45°Nbut not east of 20°W (Stresemann and Stresemann 1970).

Fledglings leave the colonies in the southern hemisphereafter the adults in May, and arrive in Canadian waters beforemid-June (Rowan 1952; Voous and Wattel 1963; Warham1990). Stresemann and Stresemann (1970) suggested thatthese birds seem not to mix with adults but stay in juvenileflocks; however, the authors did not explain how they distin-guished between age-classes.

It is believed that Greater Shearwaters migrate later insummer in an easterly direction across the North AtlanticOcean to the European coast (Wynne-Edwards 1935; Palmer1962; Cramp and Simmons 1977; Powers 1983; Brown1983) and arrive at the breeding grounds at the end of thesouthern winter, between August and September (Tristan daCunha and Nightingale, Inaccessible, Gough, and Falklandislands). Brewer et al. (1999) report that this migration pat-tern is also reflected by band recoveries from birds bandedon migration off New Brunswick.

Although there is less discussion about the timing of mi-gration of Greater Shearwaters in Canadian waters, severaltheories have been put forward about the actual migrationflyways. As indicated by Hagen (1952), who reported bandrecoveries off western Greenland from birds banded at thecolonies, one theory describes a northward movement ofGreater Shearwaters to south Greenland waters later duringthe northern summer (Voous and Wattel 1963; Graefe 1973;Brown 1988; Alerstam 1993; Durinck and Falk 1996). ButPowers et al. (1979) and Powers and Van Os (1979) reportedhigh numbers of birds during October, November, and De-cember in the Gulf of Maine and Georges Bank region,when breeding shearwaters are already back at their coloniesin the South Atlantic Ocean. Root (1988) did not record anyGreater Shearwaters during Christmas Bird Counts, indicat-ing that they have all left by this time (or are too far offshoreto be recorded). Once the moult of primary and secondaryfeathers is finished in Canadian waters, Greater Shearwatersare believed to cross the Atlantic eastward to the coasts ofEngland and France (Wynne-Edwards 1935; Voous andWattel 1963; Warham 1990; Alerstam 1993); but Rowan(1952) and Stresemann and Stresemann (1970) question this,since the timing of migration of observed birds does notmatch this hypothesis. In addition, the theory does not dif-ferentiate between breeders and nonbreeders (for eastwardtransatlantic migration of nonbreeders see Brewer et al. 2000).Another theory suggests that the southward migration routeto the breeding colonies follows the West African coast(Voous and Wattel 1963), but this is unlikely to be the casefor most of the population; according to Rowan (1952), thebirds observed off West Africa are probably nonbreeders,and most Greater Shearwaters migrate southward in the mid-Atlantic or along the western Atlantic Ocean.

Moulting strategies are described in detail by Stresemannand Stresemann (1970) and Brown (1988). Salomonsen(1967b) suggests that for most of the Greater Shearwaterpopulation, primary moult occurs in August west of Green-land, but Brown (1988) refers to the southeast shoal off

Newfoundland, and to a lesser extent on the Scotian Shelf,as the major moulting grounds, and indicates that moultingis energetically expensive and should take place where foodcan be found. Primary moult is detectable at sea from gapsin the wings. Salomonsen (1967b) mentions that GreaterShearwaters postpone flight-feather moult until they arriveat the wintering grounds. The complete primary moult takesplace in adult birds within 40 days between May andAugust, when up to 6 inner primaries may be growingsimultaneously (Ginn and Melville 1983; Warham 1990).Stresemann and Stresemann (1970) suggest a moult rate of5 mm/day, which allows for new plumage within 90 daysduring May–August, peaking in June. H.K. Lambert (citedin Stresemann and Stresemann 1970) and Ginn and Melville(1983) indicate that the fact that the complete moult inGreater Shearwaters occurs during the northern summerseems not to handicap their flight performance. Salomonsen(1967b) and Brown (1988) reported that no Greater Shear-waters were flightless during this time, but that they do havedifficulty taking off, particularly when the sea is calm. Forbreeding birds, body and wing plumage is all renewed in thenorthern hemisphere; juvenile birds in the first year moultonly body feathers, not primaries. Nonbreeders off New-foundland start moulting their primaries in June (H.K. Lambert,cited in Stresemann and Stresemann 1970), but were ob-served in moult at other times elsewhere in the AtlanticOcean,such as France in November and Tierra del Fuego inJanuary (e.g., Brown 1988). Therefore, Greater Shearwatersin Canadian (Rowan 1952, cited in Stresemann andStresemann 1970; Brown 1988) and European waters (Rowan1952; Palmer1962) between August and November are verylikely nonbreeders. Powers and Van Os (1979) report thatsubstantial numbers of nonbreeding Greater Shearwatersgather in the northwestern Atlantic before migrating south.The authors estimate that at least 3.5% of the total popula-tion are nonbreeders (juveniles and subadults), but this islikely a considerable underestimate, since in most seabirdspecies, half or more of the total population are nonbreeders(Diamond et al. 1986).

The timing of Greater Shearwater migration revealed bythe PIROP data does not match the existing theory as out-lined in Wynne-Edwards (1935) and Brewer et al. (2000).One theory mentions a northward movement of moultingGreater Shearwaters to south Greenland during the latenorthern summer (Hagen 1952; Stresemann and Stresemann1970; Alerstam 1993), but the 20 years of PIROP data donot support a true northward movement of Greater Shearwaterslater in the summer (Fig. 8). Salomonsen (1967b) and Durinckand Falk (1996) report Greater Shearwaters off Greenland inAugust (Voous and Wattel 1963 (mid-July); Salomonsen1967b reports large flocks of up to 30 000 birds), but theirnumbers of Greater Sheawaters seem to fluctuate from yearto year and it has been suggested that the movements ofGreater Shearwaters around the Atlantic Ocean follow sea-sonal peaks in local food sources (Brown et al. 1981). Ourdata show that Canadian waters play a role as moultinggrounds for breeders (Fig. 13), as indicated by Brown(1988). In the absence of any moult observations from westGreenland, our data do not agree with Salomonsen’s (1967b)statement that the west Greenland region is the moultingground for most of the Greater Shearwater population. Al-

© 2000 NRC Canada




though numbers of birds in moult drop after June (Fig. 4),we suggest that breeders return southward directly to theircolony locations by the end of August; there is insufficienttime for them to carry out a transatlantic migration beforereaching their breeding grounds in September. GreaterShearwaters observed in the northwest Atlantic after mid-July are very likely nonbreeders. Numbers of Greater Shear-waters peak at least 1 month later in the Bay of Fundy thansouth of Newfoundland, and are smaller (F. Huettmann, unpub-lished data; L. Murison, unpublished data for Grand Manan;C. Haycock, unpublished data for Brier Island). GreaterShearwaters (which must be nonbreeders) are observed fromJuly through December in the Bay of Fundy and Gulf ofMaine (Powers et al. 1979). No systematic surveys havebeen carried out using standardized methods to clarify thestatus of Greater Shearwaters moulting in the lower Bay ofFundy, such as in the Brier Island and Grand Manan region(Finch et al. 1978; Brown 1988; Huettmann and Diamond1998; L. Murison, unpublished data for Grand Manan; C.Haycock, unpublished data for Brier Island).

Northern GannetsNorthern Gannets breed at only six colonies in North

America (Nelson 1978; Lock et al. 1994). Brewer et al.(1999) show that spring migration begins in February foradults, but not until early March for subadults and April forjuveniles (Powers et al. 1979). Schneider and Heinemann(1996) and Powers et al. (1979) report that the spring migra-tion route of gannets wintering along the mid-Atlantic coastof the U.S.A. followed the edge of the continental shelf, andthat migration peaked in April and was completed by mid-May. Adults arrive at the breeding grounds in mid-April,younger birds a month later (Moisan and Scherrer 1973;Nelson 1978). For early October, Powers et al. (1979) reportimmatures in the Gulf of Maine (see also Powers and Brown1987). Nelson (1978) also reports that the return journey isfaster than the southward movement (ca. 40–100 vs. 25–35 km/day). Banding data show that these birds winter mainlybetween Florida and Texas (Brewer et al. 2000; subadults,Moisan and Scherrer 1973), whereas Powers (1983) reportshigh numbers of wintering birds off New York City. Root(1988) reports Christmas Bird Count observations along theAtlantic coast from Florida to Cape Cod, with highest num-bers in east North Carolina. Juveniles and subadults reachthe Gulf of Mexico by January, but adults do usually notpass beyond the east coast of Florida. For European Gan-nets, Thomson (1974) reports evidence that many immaturebirds remain in the wintering area throughout the breedingseason. Transatlantic migration of North American birds isproven by recoveries from the western Atlantic extending asfar as West Africa, Spain, Ireland, and Iceland (Thomson1974; Brewer et al. 2000). Movement patterns vary with age;the most extensive migration is undertaken by juveniles, andfirst-year birds are rarely found near the breeding area (Nel-son 1978).

Analysis of movements of gannets using band recoveries,as for Thick-billed Murres, is also complicated by the exis-tence of several different banding schemes (Moisan andScherrer 1973; Thomson 1974; Brewer et al. 2000). Youngnonbreeders are not constrained by the need to provison

chicks, and so are able to disperse away from colonies (Nel-son 1978). However, almost no immature-plumaged birdswere found north of 55°N during the breeding season(Figs. 6 and 12; compare Huettmann and Lock 1997). Ourdata for the breeding season show that most immatures canbe found in the proximity of colonies (Fig. 12), except onGeorges Bank (Powers and Backus 1987; Powers andBrown 1987), the Scotian Shelf, and the lower Bay of Fundy(Huettmann and Diamond 1998; L. Murison, unpublisheddata for Grand Manan; C. Haycock, unpublished data forBrier Island). The small numbers of immatures observed inthe Gulf of Maine and Bay of Fundy and on the ScotianShelf indicate that some immatures, perhaps first-year birds(Nelson 1978), could stay far away from colonies during thebreeding season. In winter (November–February), no imma-ture gannets were observed north of 47°N, reflecting thestrong seasonality of the breeding grounds in boreal waters(Fig. 6). The fall (September–October) distribution of imma-ture gannets shows a fast migration away from the colonies,along either the Nova Scotia coast or the shelf edge. Wehave no indication (e.g., occasional observations, own data)that gannets take a short cut overland between the St. Law-rence River (e.g., the gannet colony on Bonaventure Island)and the Gulf of Maine. The importance of Cabot Strait, CapeCod, and the lower Bay of Fundy for these birds in thepostbreeding season becomes clear from Fig. 12. All thesemarine areas are recognized already as marine “hotspots”(Brown 1986; Powers and Brown 1987).

Herring GullsHerring Gulls breed widely throughout the boreal and

Low Arctic zones of Canada (Lock et al. 1994); adults arephilopatric (Gross 1940; Kadlec and Drury 1968). Gross(1940) reports Herring Gulls in the vicinity of breeding col-onies in the Bay of Fundy from the end of February. Brown(1968) reports Herring Gulls in April and May no farthernorth than the Grand Banks. The same author reports no ju-venile gulls outside harbours in April and May, but Gross(1940), for the same season, reports some juvenile birdsaround the colonies in the Bay of Fundy. Banding data forHerring Gulls in Brewer et al. (2000), Threlfall (1978), andGross (1940) show a wide general dispersal after fledging,including a substantial northward movement, e.g., fromNewfoundland as far as Greenland. From November on,young birds then show a southward movement (Gross 1940;Threlfall 1978; Patton 1988; Brewer et al. 2000), with anaverage distance of >1500 km from colonies in winter(Threlfall 1978). According to Gross (1940) and Brewer etal. (2000), second- and third-year birds move shorter dis-tances, and adults move least of all. From early fall on,Powers et al. (1979) report large movements of birds in thefishing areas of Georges Bank, the Gulf of Maine, andsouthern New England, peaking in October. By winter, mostyoung birds have moved to the U.S. eastern seaboard, espe-cially in the New York City region (Gross 1940; Kadlec andDrury 1968; Threlfall 1978; Powers 1983; Brewer et al.2000). Patton (1988) and (Root 1988) report that a large pro-portion of immature Herring Gulls occurs throughout mostof the species’ winter range, while most of the adults remainon or near their breeding range, not migrating as far as the

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640 Can. J. Zool. Vol. 78, 2000



immature birds do. Herring Gulls wintering off Newfound-land (for Sable Island see also McLaren 1981) likely comefrom farther north or the Great Lakes region (Threlfall 1978;Brewer et al. 2000); the wintering population in the Bay ofFundy is also not of local origin (Gross 1940; Kadlec andDrury 1968). Young birds reach the Gulf Coast and CentralAmerica in January (Kadlec and Drury 1968; Patton 1988);the maximal winter range of immature birds extends to Panamaand the West Indies, where birds can stay until they returnnorth in April (Kadlec and Drury 1968; Powers et al. 1979;Powers 1983; Brewer et al. 2000).

Our PIROP data indicate that the early-winter distributionof immature Herring Gulls is concentrated in the Gulf ofMaine, north of Newfoundland, and along the LabradorBanks (Fig. 9). Immature Herring Gulls, unlike Iceland Gulls,are not found along the ice edge. The breeding-season distri-bution of immature Herring Gulls is characterized by denseconcentrations in the St. Lawrence region and along the shelf-break from the Labrador Banks. The St. Lawrence area seemsto harbour a high proportion of immature birds during thebreeding season. The prebreeding season is identical withthe winter distribution, with few immature Herring Gullsnorth of 47°N (see also Kadlec and Drury 1968; Threlfall1978). The Grand Banks do not show any substantial use byimmature Herring Gulls, which is in agreement with Brown(1968). Powers et al. (1979) discuss the influence of fishingactivities on the distribution of Herring Gulls. Data on theimpact of fishing activities on pelagic seabirds have not beencollected in Eastern Canada, so unfortunately we cannot eval-uate the effects of fisheries on seabird distribution; to ourknowledge the at-sea distribution of immature Herring Gullsis influenced not so much by fishing vessels but rather byterrestrial activities, like those at open landfills or habours(Gross 1940; Brown 1968; see also Patton 1988).

Iceland GullIceland Gulls breed mostly in Greenland and to a lesser

degree in Arctic Canada (Brown et al. 1975; Powers 1983;Boertmann et al. 1996). In April–May, Brown (1968) ob-served birds in the Labrador Sea but not far from the coastof Greenland. After breeding, banding data show that thesebirds winter in the Atlantic Provinces and the Great Lakes(Brewer et al. 2000; for immatures from Greenland recov-ered in the western and eastern Atlantic see Salomonsen1967a). Wintering birds have been reported far from shore,e.g., off Sable Island (McLaren 1981) and the Flemish Cap,but not farther south than New York City (Powers 1983).Root (1988) presents Christmas Bird Counts of IcelandGulls in the Gulf of St. Lawrence, including high numbers atthe extreme southeast point of New Brunswick, on the north-east side of Cape Breton Island in Nova Scotia, and aroundBonne Bay in Newfoundland.

Except for a few coastal observations, distribution and mi-gration data for Iceland Gulls are lacking. Almost no imma-ture Iceland Gulls were observed in summer on the coast ofArctic Canada (Fig. 11); most immatures were observedaway from the coast. In September, immature Iceland Gullswere observed only off the coast of Greenland (Boertmannet al. 1996). This indicates that the Iceland Gull is a trulyarctic species and that the west Greenland coast serves as a

source of Iceland Gulls in Canadian waters (see Evans1984). The migration flyway stretches southward acrossDavis Strait to the Grand Banks and farther down to theScotian Shelf (Fig. 7). We cannot evaluate banding datapresented by Salomonsen (1967a) regarding the transatlanticmigration of immatures because they are insufficient. Ourfindings are in agreement with Brown (1968), who foundIceland Gulls (age unspecified) in April south of Greenland.Powers’ (1983) finding that birds winter far from the coastdoes not fully agree with our winter data, e.g., birds wereclose to land in the Bay of Fundy, St. Lawrence region, andNova Scotia, but Powers’ (1983) surveys did not includecoastal areas.

Glaucous GullGlaucous Gulls breed in Greenland and in the Canadian

Arctic south to central Labrador (Salomonsen 1967a; Brownet al. 1975; Powers 1983; Boertmann et al. 1996). In April–May, Brown (1968) observed birds only close to Greenlandand nowhere else in the Labrador Sea. The North Americanpopulation winters mostly between south Labrador andNorth Carolina (Salomonsen 1967a; Grant 1986), but Powers(1983) reports wintering birds as far south as Cuba. ChristmasBird Counts report Glaucous Gulls along the North AmericanAtlantic coast, Great Lakes, Gulf of St. Lawrence, PrinceEdward Island, and north Nova Scotia (Root 1988). Manyscattered but regular counts of Glaucous Gulls along the At-lantic coast south of Maine exist, and it is known that duringwinter they feed in large multispecies flocks with HerringGulls and others (Root 1988).

There is a complete lack of published distribution and mi-gration data for Glaucous Gulls in the study area (but seeSalomonsen 1967a). All observations of immatures duringthe breeding season come from north of 55°N (Figs. 7 and11), qualifying the Glaucous Gull as a truly arctic gull. Al-most all observations made during the breeding season arefrom along the west Greenland coast, or to a lesser degreeoffshore throughout Davis Strait. This could indicate thatalong the west Greenland coast, productivity of GlaucousGulls for Davis Strait is very high, and it serves as a sourcefor the population (Salomonsen 1967a; Boertmann et al.1996). Salomonsen (1967a) showed that no banded birdsfrom Greenland were recovered abroad; but our PIROP datashow that during the winter almost all observations of imma-ture Glaucous Gulls are made south of Greenland, on theLabrador Banks, and on northern parts of the Grand Banks.A higher concentration is also found southwest of New-foundland; only 5 records come from as far south as theGulf of Maine (Figs. 11 and 7). This indicates that Brown’s(1968) “Glaucous Gulls are coastal in spring” (referring toNewfoundland and Greenland) cannot apply to the rest ofthe study area. Secondly, Fig. 7 indicates that immatureGlaucous Gulls do not migrate as far as Iceland Gulls do.

Great Black-backed GullGreat Black-backed Gulls breed from west Greenland and

north Labrador south to New York City (Powers 1983; Locket al. 1994; Boertmann et al. 1996). Brown (1968) showsthat juveniles stay inshore during April and May. Mean re-covery distances were greater in winter than in summer.

© 2000 NRC Canada




Band recoveries were made along the coast, but substantialoverland travel occurs (Brewer et al. 1999). Powers et al.(1979) report that after breeding, large movements of birdsin the fishing areas of Georges Bank, the Gulf of Maine, andsouthern New England peak in October. The birds spend thewinter along the coast, but rarely farther south than Wash-ington, D.C. (Powers et al. 1979; Powers 1983). Root (1988)shows, from Christmas Bird Counts, that Great Black-backed Gulls are abundant in winter from Delaware Baynorth to the Bay of Fundy, foraging along the coast but alsooffshore up to 150 km from the coast (see also McLaren1981 (Sable Island)).

Great Black-backed Gulls’ movements are poorly known;PIROP presents the only existing data on this subject, whichshow that in winter immature Great Black-backed Gulls canbe found far out at sea, rather than having a strictly coastaldistribution (Fig. 9). In the postbreeding season there arehigh concentrations along the west Greenland coast, north ofNewfoundland and south of Labrador, and off Cape Cod.Except for Cape Cod, it appears that young Great Black-backed Gulls are concentrated around breeding colonies.There are no major breeding places for Great Black-backedGulls in Canada north of 53°N (Fig. 5), but there are manyin west Greenland (Boertmann et al. 1996). Since the distri-bution of immature, nonbreeding birds in the breeding sea-son is not close to the coast, we suggest that immature GreatBlack-backed Gulls are not constrained in their movementsby colony locations, but range or disperse over long dis-tances. Our data clearly indicate that Brown’s (1968) state-ment concerning the south Labrador Sea (“juveniles beingcoastal in April throughout May”) cannot apply to the GrandBanks or Gulf of Maine. Powers et al. (1979) discuss theinfluence of fishing activities on the distribution of GreatBlack-backed Gulls; as mentioned for Herring Gulls, thereexists no measurement of fishing activities in our data, but toour knowledge the distribution of immature Great Black-backed Gulls is not strongly affected by fishing vessels.

Black-legged KittiwakesBlack-legged Kittiwakes breed on Newfoundland, in the

Gulf of St. Lawrence, and in the High Arctic (Nettleship1980; Baird 1994); small numbers have recently colonizedthe Bay of Fundy (Kehoe 1994; A.W. Diamond, unpublisheddata). Band recoveries come from Iceland, Greenland, Rus-sia, Spitzbergen, Norway, and Britain, showing that Black-legged Kittiwakes are long-distance transatlantic migrants(Powers 1983; for birds banded as nestlings in Europe andrecovered in Canada from October to January see Breweret al. 2000). Black-legged Kittiwakes are the second mostcommon birds in the Labrador Sea in spring (Brown 1968,cited in Baird 1994); nonbreeding summer visitors can befound along the Labrador coast (Baird 1994). Black-leggedKittiwakes migrate because of a waning food supply andchanges in water temperature, but their migration behaviouris not known, except that they concentrate in spring at theedges of sea ice (Bradstreet 1982 in Baird 1994). Brown(1968) reports 53°N as the limit of the northern spring range(April–May) and confirms the “landward” spring migrationreported by Wynne-Edwards (1935). Adult Black-leggedKittiwakes seem to move to the breeding colonies and leavejuvenile nonbreeders behind in the wintering areas; for

April–May, Brown (1988) reports a ratio of ca. 1 adult to 40first-winter Black-legged Kittiwakes in the south LabradorSea. Brown (1988) reports that juveniles on the southwestGrand Banks are still migrating in mid-May. After fledging,immature birds first stay with their parents and then dispersefrom the colony (Baird 1994). Powers et al. (1983) reportthat birds are common on Georges Bank after October. Juve-niles are found close to land in winter, when adults are pe-lagic (Powers 1983; Baird 1994). Rees (1963) reports largenumbers of first-winter birds in the Strait of Belle Isle inNovember; Baird (1994) and Powers (1983) show that New-foundland is an important overwintering area for birds fromGreenland and the northeast Atlantic and European Arcticoceans. During Christmas Bird Counts, Root (1988) reportsover 1000 individuals per party-hour 1969 in Passama-quoddy Bay and on the border between U.S.A. and Canada,but numbers vary greatly.

Analysis of movements of Black-legged Kittiwakes fromband recoveries is also complicated by the existence of sev-eral different banding schemes (Baird 1994; Brewer et al.2000). Our PIROP data for the prebreeding season show thatjuvenile Black-legged Kittiwakes are concentrated on theGrand Banks and south of Greenland, with a very clear mi-gration flyway from the Grand Banks to south Greenland(Fig. 10); this is probably due to the presence of ice coveroff Labrador when Black-legged Kittiwakes, particularly theArctic breeding population, begin to migrate north to theirbreeding grounds. For the breeding season the data show ju-veniles far out in Davis Strait (Fig. 10), which contradicts anearlier suggestion that during the breeding season Black-legged Kittiwakes are concentrated at the coast (e.g., Baird1994). This view likely arose because no differentiation wasmade between breeders and nonbreeders; also, Davis Straitseems to constitute a distinct ecosystem. As described inBaird (1994), numbers of juvenile Black-legged Kittiwakesoff south Labrador are very high during the breeding season,but cannot be accounted for by the local breeding populationin Eastern Canada or the Canadian Arctic. We suggest thatthese nonbreeding birds are from the East Atlantic, as indi-cated by some band recoveries (Brewer et al. 1999), or pos-sibly from Greenland (Donaldson et al. 1997). Tagging,banding, and telemetry work will help to explain this phe-nomenon. In the postbreeding season there are no clear mi-gration patterns, but observations and reports indicatesoutherly migration along the coast of Labrador, through thecentre of the Labrador Sea, close along the coast of New-foundland, around the Tail of the Grand Banks, and alongthe shelf edge off Nova Scotia (Baird 1994).

Thick-billed MurresNinety-five percent of Canadian Thick-billed Murres

breed in the Eastern Canadian Arctic (Gaston 1980; Nettle-ship 1980; Nettleship and Birkhead 1985), and banding showsthat they are largely philopatric (Kampp 1983; Brewer et al.2000; but see Kampp and Falk 1998). Birds from large coloniesin west Greenland contribute a large but unknown proportionof the distribution records in PIROP. Northward movementof juveniles after they leave the Newfoundland colonies isreported by Tuck (1961), but Gaston (1980) and Gaston andJones (1998) report a rapid southward movement down thewest Greenland coast from High Arctic colonies. Tuck (1961),

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Gaston (1980), and Gaston and Jones (1998) suggest twomajor autumn migration routes for Thick-billed Murres: theHigh Arctic and west Greenland birds would follow the westGreenland coast before crossing Davis Strait to Labradorand Newfoundland, and other birds would travel throughHudson Strait down the coast of Labrador to Newfoundlandand the Grand Banks (for Canadian birds off Greenland seealso Orr and Ward 1982 and Kampp 1988). But these migra-tion routes are challenged by Kampp (1988), who suggestsone major central migration route from the High Arctic south-ward, with wintering areas off west and south Greenland andNewfoundland. Gaston (1980) concludes that birds are flight-less for at least 1 month during postbreeding dispersal, whentheir migration route follows ocean currents. Thick-billedMurres winter mainly off the Grand Banks (Gaston 1980;for wintering birds off west and south Greenland see Kampp1988) but also as far south as Massachusetts (Powers andBrown 1987). Gaston (1980) reports that in November andDecember, birds are likely concentrated north of 49°N, andmove south later because of ice cover. According to Christ-mas Bird Counts, Thick-billed Murres winter from the Gulfof St. Lawrence south to New Jersey (Root 1988). First-winter birds are recovered earlier than adults during the win-ter hunt off Newfoundland (Donaldson et al. 1997); breedingbirds arrive after December (Gaston and Jones 1998). Abouthalf of the west Greenland birds also winter off Newfound-land, and most may be young birds (Gaston 1980; Kampp1988). Thick-billed Murres banded in Lancaster Sound wererecovered in substantial numbers off Greenland in September–November (Tuck 1961; Kampp 1983). European birds arealso found in Canadian waters (Uspenski 1956; Nettleshipand Birkhead 1985; Nettleship 1996) and off southwestGreenland (Gaston 1980; Kampp 1988).

Moulting Thick-billed Murres can be recognized at seafrom gaps in the wing feathers or because they are com-pletely flightless. Adults begin a postnuptial moult soon af-ter breeding and leaving the colony (Tuck 1961). During thistime they become flightless for about 4–6 weeks (Gastonand Jones 1998); the same authors also report that this moultoccurs during September and October off Greenland, but isfinished by the time birds arrive in Newfoundland in earlyNovember. In first-year nonbreeders the timing of the firstfull moult (body and wing feathers) is not known from directobservation; Gaston and Jones (1998) suggested that it oc-curs during summer, when birds do not attend the colony. In-dividuals and populations can vary in the timing of theirmoult (Tuck 1961). Moulting grounds have not been identi-fied specifically in the literature, but can be inferred from thetiming of moult, e.g., if adults moult in September and Octo-ber, the moulting ground for most birds should be near Lan-caster Sound and west Greenland (High Arctic breeders) andLabrador (Low Arctic breeders).

Analysis of movements of Thick-billed Murres usingbanding recoveries is made difficult by the existence ofseveral different banding schemes within their distribution(Kampp 1988; Brewer et al. 2000), and by a highly biaseddistribution of recoveries that reflects mainly the distributionof hunters. The immature plumage of Thick-billed Murres isso similar to that of winter adults that immatures can rarelybe distinguished at sea. However, they leave the breedingcolonies, accompanied by the male parents, at only one-

quarter of adult size (Gaston and Jones 1998), and so can bedistinguished until they reach adult size, probably about 4–6 weeks later. Therefore, it is not surprising that juvenileThick-billed Murres were observed mainly in the vicinity oftheir colonies in Davis Strait between July and October(Fig. 10). Our findings confirm the route of southward mi-gration indicated in Gaston (1980) and Gaston and Jones(1998); however, they do not support a rapid southward mi-gration of juveniles between August and October, suggestinginstead a slow movement to southern Davis Strait or evensome initial northward movement, as is shown by someband recoveries (Kampp 1988; Brewer et al. 2000; Fig. 6).Adults and juveniles are known to separate several weeks af-ter leaving the colonies (Gaston 1998; Gaston and Jones1998); in northern populations adults migrate southward, butjuveniles may stay in the area or go even slightly northwardfirst, returning later, from October on. But juveniles, or birdsin moult, might dive when approached by a vessel, whereasadults fly off and are the only visible part of this association.At sea, the sex of adults cannot be distinguished, but basedon females returning to colonies when chicks have alreadyleft, it has been suggested that males stay with the juveniles,and females migrate separately (Gaston and Jones 1998).The southward winter movement goes beyond the waters ofNewfoundland (F. Huettmann, unpublished data for the Bayof Fundy).

Pelagic observations of moulting birds are few, owing tothe difficulty of identifying the larger auks (Razorbill, Com-mon, and Thick-billed murres) at sea, particularly in basicplumage. Thick-billed Murres moult outside the breedingseason, but details and areas are not well known; the loca-tions of moulting Thick-billed Murres have not been mappedbefore (Fig. 13). Nettleship (1996) does not discuss moult-ing patterns of auks; our data do not agree with Gaston andJones (1998) that Thick-billed Murres moult within a 4- to6-week period and have finished moulting in Novemberwhen found on the Grand Banks. On the contrary, althoughour data do show some moult in August and September, itmainly occurs in November and December (Fig. 4), whichwould mean that the moult usually does not start immedi-ately after the adults leave the colony. Other possible expla-nations to be kept in mind are that the observations are ofdifferent populations (e.g., from Europe, see also Kampp1988) with different moulting schedules; that nonbreedersmoult at different times than breeders; or that adult malesand females moult at different times. The locations of ob-served moulting Thick-billed Murres confirm the GrandBanks as a wintering and moulting ground in early winter(November and December) for a proportion of the popula-tion, although most birds were seen farther north than wouldbe expected from a fast postbreeding southward dispersal.Although some moulting birds were seen in almost allmonths of the year, observations peaked between Septemberand December (Fig. 8). Occasional observations from southof Newfoundland in February–April indicate either a post-and pre-breeding moult, perhaps by different segments of thepopulation (breeders and nonbreeders) or, more likely, thefirst complete moult of first-year birds (as suggested byM.G. Bédard, cited in Nettleship and Birkhead 1985), whichsupports the view of differences in timing of the moult indifferent age-classes.

© 2000 NRC Canada




GeneralThis analysis suggests the existence of several biogeo-

graphic borderlines and transition zones. (i) Latitude 55°N isa boundary between arctic gull species, such as Iceland andGlaucous gulls (to the north) and Herring and Great Black-backed gulls off the coast of Labrador during the breedingseason. It is also the northern limit of moulting Thick-billedMurres in winter, of the spring range of Black-legged Kitti-wakes, and of adult Northern Gannets. Diamond et al. (1986,1993) used this latitude to divide the southern from thenorthern breeding regime. (ii ) Latitude 45°–46°N is thenorthern limit of juvenile Northern Gannets and of our con-sistent summer and fall records of Greater Shearwaters(though varying numbers are reported off Greenland). (iii ) Inthe Canadian Arctic between 65° and 72°N, few NorthernFulmars and Black-legged Kittiwakes were found during thebreeding season. None of these borderlines or transitionzones match any found using environmental data (F. Huett-mann and A.W. Diamond, unpublished data) or previousclassification schemes based mostly on oceanographic work

in the 1960s and 1970s that summarizes surface patterns atsea rather than the whole oceanography (see Salomonsen1965, 1972; Ashmole 1971; Dunbar 1968 in Brown et al.1975). Using PIROP data and Cart (classification and re-gression tree) analysis, Huettmann and Lock (1997) found aline at -52°N for August that divided the Northern Gannetdistribution from the Northern Fulmar distribution. We sug-gest that the area around 55°N reflects a biological border-line between arctic and boreal waters (for an example offluctuations in such a zone see Montevecchi and Myers1997).

ConclusionsThe importance of migration routes and staging grounds is

well recognized for songbirds (Hagan and Johnston 1992)and shorebirds (Morrison and Ross 1989), but has not beenrecognized for seabirds. The scarcity of information aboutthis important subject for seabird conservation emphasizesthe need for projects that further investigate these issues; forexample, no data have been collected or monitoring projects

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644 Can. J. Zool. Vol. 78, 2000

Status of bird Time of year Location with high concentration of birds Environmental characteristic

Thick-billed Murre Juvenile Fall Lancaster Sound, Hudson Strait BaysMoulting November–

DecemberSouth Labrador Banks, Grand Banks Shallow waters

Northern Gannet Immature Winter Cape Cod Shallow and mixing regimeBreeding Grand Manan, Strait of Belle Isle Strong (tidal) currentsPostbreeding Grand Manan, Cape Cod, Cabot Strait Strong (tidal) currents

Greater Shearwater Moulting June Southeast Newfoundland, Georges Bank Shallow watersNorthern Fulmar Moulting Breeding South Labrador Banks Shallow watersBlack-legged

KittiwakeJuvenile Winter Grand Banks (south Labrador Banks in early

winter)Shallow waters

Prebreeding Tail of Grand Banks Shallow waters, mixingregime

Breeding South Labrador, Cabot Strait, off LancasterSound, off Cumberland Strait

Shallow waters, strong (tidal)currents

Postbreeding Off Lancaster Sound, northwestNewfoundland, Grand Manan

Shallow waters, mixingregime

Herring Gull Immature Winter Cape Cod Mixing regimeBreeding Cape Cod, Cabot Strait, St. Lawrence

(Northumberland Strait), Strait of Belle IsleStrong (tidal) currents

Postbreeding Cape Cod, northwest Newfoundland, GrandManan, Strait of Belle Isle, Georges Bank

Strong (tidal) currents,shallow waters

Great Black-backedGull

Immature Winter Cape Cod, Georges Bank Mixing regime, shallowwaters

Prebreeding Cabot Strait, Grand Banks Currents, shallow watersBreeding Cabot Strait, Cape Cod, south Labrador,

west GreenlandCurrents, shallow waters

Postbreeding West Greenland, northeast Newfoundland,south Labrador, Georges Bank

Shallow waters

Iceland Gull Immature Winter St. Lawrence region, west Newfoundland Coastal watersPrebreeding Ice edge Fresh/salt-water mixing

regimePostbreeding West Greenland, south Davis Strait Shallow waters, offshore

Glaucous Gull Immature Winter South Labrador, southeast Newfoundland Shallow watersPrebreeding Ice edge, south Greenland Fresh/salt-water mixing

regime, shallow watersBreeding West Greenland, Davis Strait Shallow waters, offshorePostbreeding Labrador Banks Shallow waters

Table 2. Marine areas identified as important to seabirds, by status and season (see also Fig. 1).



carried out on movements of seabirds from the Grand Banksfollowing the cod crisis. Banding of seabirds, normally donein seabird colonies, is not the prime method for investigatingseabird movements because the existence of different band-ing schemes makes investigation of recoveries difficult, be-cause banded birds cannot be detected at sea, and becauserecoveries are very biased by patterns of anthropogenic mor-tality, e.g., more than 90% of Thick-billed Murre whosebands were recovered had been shot (Gaston 1980). We sug-gest that the limited resoures available be concentrated in-stead on developing efficient tagging techniques such assatellite telemetry or tags that can be detected at sea.

The distributions of immature Glaucous Gulls, IcelandGulls, and to a lesser extent Great Black-backed Gulls indi-cate that the west Greenland coast is a centre of high densityin the study area, and is probably a source for the whole Da-vis Strait population. The marine area off west Greenland isinfluenced mainly by surface currents; for example, theGreenland current is a spin-off from the Gulf Stream. Thisconfirms the importance of global-scale processes for DavisStrait and some of its seabird populations (for details seeSalomonsen 1965; Montevecchi and Myers 1997), and ar-gues for an ecosystem-wide management, monitoring, andconservation approach for this area.

The location of ice edges in spring is an important habitatfeature for seabirds, such as Iceland Gulls, Glaucous Gulls,Black-legged Kittiwakes, and Thick-billed Murres, on theirnorthward spring migration (McLaren 1982). The speciesdistribution of immatures shows that strong seasonality pat-terns can be found in the northwest Atlantic. Species distri-bution patterns show strong latitudinal gradients with severalclear biological borderlines and transition zones.

Table 2 summarizes our identification of marine areas im-portant for seabird conservation. The west Greenland coast(Great Black-backed Gull, Iceland Gull), Cape Cod (North-ern Gannet, Herring Gull, Great Black-backed Gull), GrandBanks (Thick-billed Murre, Black-legged Kittiwake, GreatBlack-backed Gull), Labrador Banks (Thick-billed Murre,Northern Fulmar, Black-legged Kittiwake, Great Black-backed Gull, Glaucous Gull), southwest Newfoundland(Greater Shearwater, Iceland Gull, Glaucous Gull), andGrand Manan (Northern Gannet, Black-legged Kittiwake,Herring Gull, Great Black-backed Gull) seem to be key ar-eas during portions of the life cycle for the species dis-cussed. We draw particular attention to the occurrence ofmoult during and after migration in some of these seabirds(Thick-billed Murre, Greater Shearwater, Northern Fulmar),since this occurs at times and in places of extreme vulnera-bility, especially to oil spills.

Acknowledgements

Bird-banding data were kindly provided by E. Dunn andA.J. Gaston of the Canadian Wildlife Service Banding Of-fice. We are grateful to Tony Lock, Geoff Howell, and theACWERN team for support and help. The review processwas appreciated; K. Kampp and two anonymous reviewershelped to improve the manuscript. F.H. acknowledges thestimulating thoughts put forward by Sophia Anna and JuliaLinke. This is paper No. UNB-11 from ACWERN.

References

Alerstam, T. 1993. Bird migration. Cambridge University Press,Cambridge.

Ashmole, N.P. 1971. Seabird ecology and the marine environment.In Avian biology. Edited byD.S. Farner and J.R. King. Aca-demic Press, New York. pp. 223–286.

Backus, R.H., and Bourne, D.W. (Editors). 1987. Georges Bank.MIT Press, Cambridge, Mass.

Baird, P.H. 1994. Black-legged Kittiwake (Rissa tridactyla). In Thebirds of North America. No. 92.Edited byA. Poole and F. Gill.The Academy of Natural Sciences, Philadelphia, and The Amer-ican Ornithologists’ Union, Washington, D.C.

Boertmann, D, Mosbech, A., Falk, K., and Kampp, K. 1996.Seabird colonies in western Greenland (60°–79°30′N. lat.).NERI Tech. Rep. No.170, National Environmental Research In-stitute, Roskilde, Denmark.

Bradstreet, M.S.W. 1982. Occurrence, habitat use, and behavior ofseabirds, marine mammals and arctic cod at the Pond Inlet iceedge. Arctic,35: 28–40.

Braune, B.M. 1989. Autumn migration and comments on thebreeding range of Bonaparte’s Gull,Larus philadelphia, in east-ern North America. Can. Field-Nat.103: 524–530.

Brewer, A.D., Diamond, A.W., Woodsworth, E.J., Collins, B.T.,and Dunn, E.H. 2000. Atlas of Canadian bird banding recover-ies, 1921–95. Can. Wildl. Serv. Spec. Publ. In press.

Brown, R.G.B. 1968. Seabirds in Newfoundland and Greenland.Can. Field-Nat.82: 88–102.

Brown, R.G.B. 1973. The transatlantic migration of European arc-tic Fulmars,Fulmarus glacialis.Can. Field-Nat.87: 312–313.

Brown, R.G.B. 1983. Birds and the sea. Oceanus,26: 3–10.Brown, R.G.B. 1986. Revised atlas of Eastern Canadian seabirds.

Bedford Institute of Oceanography, Dartmouth, Nova Scotia,and Canadian Wildlife Service, Ottawa, Ont.

Brown, R.G.B. 1988. The wing-moult of fulmars and shearwaters(Procellariidae) in Canadian Atlantic Waters. Can. Field-Nat.102: 203–208.

Brown, R.G.B., and Johnson, B. 1981. The effects of Kurdistan oilon seabirds.In Scientific Studies during the Kurdistan TankerIncident: Proceedings of a Workshop.Edited by J.H. Vander-muelen. Rep. BI-R-80-3, Bedford Institute of Oceanography,Dartmouth, Nova Scotia. pp. 203–211.

Brown, R.G.B., and Nettleship, D.N. 1984a. The seabirds of north-eastern North America: their present status and conservation re-quirements. Chap. 2.In Status and conservation of the world’sseabirds. Edited by J.P. Croxall, P.G.H. Evans, and R.W.Schreiber. Tech. Publ., International Council for Bird Preserva-tion, Cambridge, England. pp. 85–100.

Brown, R.G.B., and Nettleship, D.N. 1984b. Capelin and seabirdsin the northwest Atlantic.In Marine birds: feeding ecology andcommercial fisheries relationships.Edited by D.N. Nettleship,G.A. Sanger, and P.F. Springer. Canadian Wildlife Service, Ot-tawa, Ont. pp. 184–194.

Brown, R.G.B., Nettleship, D.N., Germain, P., Tull, C.E., and Da-vis, T. 1975. Atlas of eastern Canadian seabirds. Canadian Wild-life Service, Ottawa, Ont.

Brown, R.G.B., Barker, S.P., Gaskin, D.E., and Sandeman, M.R.1981. The foods of Great and Sooty Shearwaters (Puffinus gra-vis andP. griseus) in eastern Canadian waters. Ibis,123: 19–30.

Cairns, D.K., Montevecchi, W.A., and Threlfall, W. 1989. Re-searcher’s guide to Newfoundland seabird colonies. Mem. Univ.Nfld. Occas. Pap. Biol. No. 14.

Carscadden, J.E. 1982. Capelin in the northwest Atlantic.In Marinebirds: feeding ecology and commercial fisheries relationships.

© 2000 NRC Canada




Edited by D.N. Nettleship, G.A. Sanger, and P.F. Springer.Canadian Wildlife Service, Ottawa, Ont. pp. 170–183.

Chapdelaine, G. 1997. Pattern of recoveries of banded razorbills(Alca torda) in the western Atlantic and survival rates of adultsand immatures. Colon. Waterbirds,20: 47–54.

Cramp, S., and Simmons, K.E. 1977. Handbook of the birds of Eu-rope, the Middle East and North Africa. Vol. I. Oxford Univer-sity Press, Oxford.

Dennis, J.V. 1981. A summary of banded North American birdsencountered in Europe. N. Am. Bird Bander,6: 88–96.

Diamond, A.W., Gaston, A.J., and Brown, R.G.B. 1986. Convert-ing PIROP counts of seabirds at sea to absolute densities. Pro-gress Notes No. 164, Canadian Wildlife Service, Ottawa, Ont.

Diamond, A.,W., Gaston, A.J., and Brown, R.G.B. 1993. 3. Amodel of the energy demands of the seabirds of eastern ArcticCanada. Can. Wildl. Serv. Occas. Pap. No. 77.

Donaldson, G.M., Gaston, A. J., Kampp, K, Chardine, J.,Nettleship, D.N., and Elliot, R.D. 1997. Winter distributions ofThick-billed Murres from the eastern Canadian Arctic and west-ern Greenland in relation to age and time of year. Can. Wildl.Serv. Occas. Pap. No. 96.

Dunbar, M.J. 1968. Ecological developments in polar regions: astudy in evolution. Prentice Hall, Englewood Cliffs, N.J.

Durinck, J., and Falk, K. 1996. The distribution and abundance ofseabirds off southwestern Greenland in autumn and winter1988–1989. Polar Res.15: 24–42.

Evans, P.G.H. 1984. Seabirds of Greenland: their status and con-servation.In Seabirds of the world: their status and conserva-tion. Edited by J.P. Croxall, P.G.H. Evans, and R.Schreiber.International Council for Bird Preservation, Cambridge, Eng-land. pp. 49–84.

Falk, K., and Moeller, S. 1995. Satellite tracking of high-arcticNorthern Fulmars. Polar Biol.15: 495–502.

Finch, D.W., Russell, W.C., and Thompson, E.V. 1978. Pelagicbirds in the Gulf of Maine. Part I. Am. Birds,32: 140–155.

Fisher, J. 1952. The fulmar. Collins, London.Furness, R.W., and Burger, A.E. 1988. Effects of energy con-

straints on seabird breeding at high latitudes. Proc. Int. Ornithol.Congr.19: 205–1217.

Gaston, A.J. 1980. Populations, movements and wintering areas ofThick-billed MurresUria lomvia in eastern Canada. Can. Wildl.Serv. Prog. Notes,110: 1–10.

Gaston, A.J. 1982. Banding Thick-Billed Murres (Uria lomvia) atNantzsch Island, N.W.T. “Studies on Northern Seabirds”Manuscr. Rep. No. 165, Canadian Wildlife Service, Ottawa,Ont. pp. 1–3.

Gaston, A.J. 1984. How to distinguish first-year murres,Uria spp.,from older birds in winter. Can. Field-Nat.98: 52–55.

Gaston, A.J. 1998. Modeling departure strategies in Auks. Auk,115: 798–800.

Gaston, A.J., and Jones, I.L. 1998. The Auks. Oxford UniversityPress, Oxford.

Ginn, H.B., and Melville, D.S. 1983. Moult in birds. British Trustfor Ornithology, Tring, Hertfordshire, England.

Graefe, F. 1973. Verbreitung des grossen Sturmtauchers (Puffinusgravis) vor der SE-Kueste Groenlands im August 1966. Vogelwelt,94: 175–182.

Grant, P.J. 1986. Gulls, a guide to identification. 2nd ed. A.D.Poyser Ltd., Calton, England.

Gross, A.O. 1940. The migration of Kent Island Herring Gulls.Bird-Banding,XI : 129–155.

Hagan, J.M., and Johnston, D.W. 1992. Ecology and conservationof Neotropical migrant landbirds. Manomet Bird Observatory,

Manomet, Miss., and Smithsonian Institution Press, Washing-ton, D.C.

Hagen, Y. 1952. Birds of Tristan Da Cunha: results of the Norwe-gian Scientific Expedition to Tristan Da Cunha 1937–1938. No.20. Det Norske Videnskaps-Akademi, Oslo. pp. 109–111.

Harrison, P. 1983. Seabirds an identification guide. HoughtonMifflin Co., Boston,.

Hatch, S.A., and Nettleship, D. 1998. Northern Fulmar (Fulmarusglacialis). In The birds of North America. No. 361.Edited byA.Poole and E. Gill. The Birds of North America Inc., Philadel-phia.

Huettmann, F., and Diamond, A.W. 1998. Seabird surveys and se-lected environmental data sets in the Bay of Fundy: findings andconclusions from monthly ferry transects Saint John – Digby –Saint John.In Coastal Monitoring and the Bay of Fundy: Pro-ceedings of the Marine Atlantic Ecozone Science Workshop.Edited byM.D. Burt and P.G. Wells. Huntsman Marine ScienceCentre, St. Andrews, N.B. pp. 85–92.

Huettmann, F., and Lock, A.R. 1997. A new software system forthe PIROP database: data flow and an approach for a seabird-depth analysis. ICES J. Mar. Sci.54: 518–523.

Humphrey, P.S., and Parkes, K.C. 1959. An approach to the studyof molts and plumages. Auk,76: 1–31.

INTERAC TYDAC. 1992. SPANS MAP user’s guide. Intera TydacTechnologies Inc., Nepean, Ont.

INTERAC TYDAC. 1993. SPANS-GIS reference manual. InteraTydac Technologies Inc., Nepean, Ont.

INTERAC TYDAC. 1995. Technical demonstration notes fromthe International SPANS Workshop, Ottawa, Ont., August 30 –September 1, 1995. Intera Tydac Technologies Inc., Nepean, Ont.

Jouventin, P., and Weimerskirch, H. 1990. Satellite tracking ofwandering albatrosses. Nature (Lond.),343: 746–748.

Kadlec, J.A., and Drury, W.H. 1968. Structure of the New EnglandHerring Gull population. Ecology,49 : 644–676.

Kampp, K. 1983. The Thick-billed murres in Greenland: move-ments, mortality and hunting—an analysis of 35 years of band-ing. Science Candidate thesis (Kobenhavns Universitet Manuscr.Rep. No. 171), University of Copenhagen, Copenhagen, Den-mark. pp. 1–167. [Translated from Danish by R.G.B. Brown.]

Kampp, K. 1988. Migration and winter ranges of Brünnich’s Guil-lemots Uria lomvia breeding or occurring in Greenland. Dan.Ornithol. Foren. Tidsskr.82: 117–130.

Kampp, K., and Falk, K. 1998. A long distance colony shift by aThick-billed Murre. Colon. Waterbirds,21: 91–93.

Kehoe, P. 1994. A New Brunswick Black-legged Kittiwake,Rissatridactyla, colony. Can. Field-Nat.108: 375–376.

Lock, A.R., Brown, R.G.B., and Gerriets, S.H. 1994. Gazetteerof marine birds in Atlantic Canada. Canadian Wildlife Service,Ottawa, Ont.

Lock, A.R., Petrie, J., and Griswold, A. 1997. PIROP softwaremanual. Canadian Wildlife Service, Atlantic Region, Halifax,Nova Scotia.

McCleave, J.D., Arnold, G.P. Dodson, J.J., and Neill, W.H. (Edi-tors). 1984. Mechanisms of migration in fishes. NATO ScientificAffairs Division and Plenum Press, New York and London.

McLaren, I.A. 1981. The birds of Sable Island, Nova Scotia. Proc.N.S. Inst. Sci.31(1).

McLaren, P.L. 1982. Spring migration and habitat use by seabirdsin eastern Lancaster Sound and western Baffin Bay. Arctic,35:88–111.

Moisan, G., and Scherrer, B. 1973. Déplacements saisonniers desfous de Bassan de l’île Bonaventure (Canada) (Sula bassana).Terre Vie,27: 414–435.

© 2000 NRC Canada

646 Can. J. Zool. Vol. 78, 2000



© 2000 NRC Canada


Montevecchi, W.A., and Myers, R.A. 1997. Centurial and decadaloceanographic influences on changes in Northern Gannet popu-lations and diets in the north-west Atlantic: implications for cli-mate change. ICES J. Mar. Sci.54: 608–614.

Morrison, R.I.G., and Ross, R.K. 1989. Atlas of Nearcticshorebirds on the coast of South America. Vol. I. Spec. Publ.,Canadian Wildlife Service, Ottawa, Ont.

Myers, P.M., Hatch, S.A., and Mulchay, D.M. 1998. Effect of im-planted satellite transmitters on the nesting behavior of murres.Condor,100: 172–174.

Nelson, J.B. 1978. The Sulidae, gannets and boobies. Oxford Uni-versity Press, Oxford.

Nettleship, D.N. 1980. A guide to the major seabird colonies ofeastern Canada: identity, distribution and abundance. “Studieson Northern Seabirds” Manuscr. Rep. No. 97, Canadian WildlifeService, Ottawa, Ont. pp. 1–133.

Nettleship, D.N. 1991. Seabird management and future research.Colon. Waterbirds,14: 77–84.

Nettleship, D.N. 1996. Family Alcidae (Auks).In Handbook of thebirds of the world. Vol. 3. Hoatzin to Auks.Edited byJ. delHoyo, A. Elliott, and J. Sargatal, Lynx Edicions, Barcelona.pp. 678–722.

Nettleship, D.N., and Birkhead, T. 1985. The Atlantic Alcidae. Ac-ademic Press, London.

Newton, I., and Dale, L. 1996. Relationship between migration andlatitude among west European birds. J. Anim. Ecol.65: 137–146.

Orr, C.D., and Ward, R.M.P. 1982. The fall migration of Thick-billed Murres near southern Baffin Island and northern Labra-dor. Arctic, 35: 531–536.

Palmer, R.S. 1962. Handbook of North American birds. Vol. 1.Yale University Press, New Haven, Conn.

Patton, S.R. 1988. Abundance of gulls at Tampa Bay landfills. Wil-son Bull. 100: 431–442.

Pennycuick, C.J. 1987a. Flight of auks (Alcidae) and other north-ern seabirds compared with southern Procellariiformes: ornitho-dolite observations. J. Exp. Biol.128: 335–347.

Pennycuick, C.J. 1987b. Flight of seabirds.In Seabirds: feedingecology and role in marine ecosystems.Edited byJ.P. Croxall.Cambridge University Press, Cambridge. pp. 43–62.

Powers, K.D. 1983. Pelagic distributions of marine birds off thenortheastern United States. NOAA Tech. Mem. NMFS-F/NEC-27.

Powers, K.D., and Backus, E.H. 1987. Energy transfer to birds.InGeorges Bank.Edited byR.H. Backus and D.W. Bourne. MITPress, Cambridge, Mass. pp. 372–375.

Powers, K.D., and Brown, R.G.B. 1987. Seabirds.In GeorgesBank. Edited by R.H. Backus and D.W. Bourne. MIT Press,Cambridge, Mass. pp. 359–371.

Powers, K.D., and Van Os, J.A. 1979. A concentration of GreaterShearwaters in the western North Atlantic. Am. Birds,33: 253.

Powers, K.D., Pittman, B.G.C., and Burrell, G.C. 1979. Distribu-tion of marine birds on the Mid- and North-Atlantic. U.S. OuterContinental Shelf Technical Progress Report, September 1978 –August 1979. Manomet Bird Observatory, U.S. Department ofEnergy, Ecological Research Division, Office of Health andEnvironmental Research, Office of Environment, Washington,D.C.

Price, J., Droege, S., and Price, A. 1995. The summer atlas ofNorth American birds. Academic Press, London.

Rees, E.I.S. 1963. Marine birds in the Gulf of St. Lawrence andStrait of Belle Isle during November. Can. Field-Nat.77: 98–107.

Rees, E.I.S. 1964. The Sooty ShearwaterProcellaria griseaon theNewfoundland Banks. Ibis,106: 118–119.

Root, T., 1988. Atlas of wintering North American Birds: an analy-sis of Christmas Bird Count data. University of Chicago Press,Chicago.

Rowan, M.K. 1952. The Great Shearwater,Puffinus gravis, at itsbreeding grounds. Ibis,94 : 97–121.

Salomonsen, F. 1965. The geographical variation of the fulmar(Fulmarus glacialis) and the zones of marine environment in theNorth Atlantic. Auk, 82: 327–355.

Salomonsen, F. 1967a. Fuglene pa Grønland. Rhodos, Copenhagen.Salomonsen, F. 1967b. Migratory movements of the Arctic Tern

Sterna paradisaeapontoppidian in the Southern Ocean. DetKongelige Danske Videnkabernes Selskap, Biologiske Meddelelser24,1, Copenhagen. p. 11.

Salomonsen, F. 1972. Zoogeographical and ecological problems inArctic birds. Proc. Int. Ornithol. Congr.15: 25–77.

Schneider, D.C., and Heinemann, D.W. 1996. The state of marinebird populations from Cape Hatteras to the Gulf of Maine.InThe Northeast Shelf ecosystem: assessment, sustainability, andmanagement.Edited by K. Sherman, N.A. Jaworski, and T.J.Smayda. Blackwell Science, Cambridge, Mass. pp. 197–216.

Siegel, C. 1994. Mastering FoxPro 2.6 special edition. Sybex, SanFrancisco.

Stenhouse, I.J., and Montevecchi, W.A. 1996. Winter distributionand wrecks of little auks (Dovekies)Alle a. alle in the northwestAtlantic. Sula,10: 219–228.

Stresemann, E., and Stresemann, V. 1966. Die Mauser der Vögel.J. Ornithol.107(Suppl.): 1–148.

Stresemann, E., and Stresemann, V. 1970. Über Mauser und Zugvon Puffinus gravis. J. Ornithol.111: 378–393.

Thomson, A.L. 1974. The migration of the gannet: a reassessmentof British and Irish ringing data. Br. Birds,67: 89–103.

Threlfall, W. 1978. Dispersal of Herring Gulls from the Witless Baysea bird sanctuary, Newfoundland. Bird-Banding,49: 116–124.

Tuck, L.M. 1961. The murres: their distribution, populations andbiology—a study of the genusUria. Can. Wildl. Monogr. Ser.No. 1.

Uspenski, S.M. 1956. The bird bazaars of Novaya Zemlaya. Cana-dian Wildlife Service, Ottawa, Ont. [Translated from Russian,1958 (Translations of Russian Game Reports. Vol. 4. No. 159).]

Voous, K.H., and Wattel, J. 1963. Distribution and migration of theGreater Shearwater. Ardea,51: 143–57.

Warham, J. 1990. The petrels, their ecology and breeding systems.Academic Press, London.

Wilson, R.C.H., and Addison, R.F. 1984. Health of the northwestAtlantic. Environment Canada and Department of Fisheries andOceans, Ottawa, Ont.

Woods, RW. 1970. Greater Shearwater,Puffinus gravis, breeding inthe Falkland Islands. Ibis,112: 259–260.

Wynne-Edwards, V.C. 1935. On the habits and distribution of birdsin the North Atlantic. Proc. Boston Soc. Nat. Hist.40: 233–346.



seabird migration in the canadian northwest atlantic ocean: moulting locations and movement patterns...

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