102

Favourable Lake and AttawapiskatLake. Dr. Prince indicated that atFavourable Lake they had a canoeand did portage it through the bushfor many kilometres in order toaccess remote lakes. When settingand hauling nets in lakes near themine they tied two oil drums under acouple of poles strapped across thestruts of the canoe. These"outriggers" prevented overturning.But they were hot portaged to other

lakes where everyone took theirchances, including the nonswimmerHope. Dr. Prince also indicated thatthe raft used on Rathouse Bay wasthe property of the local people whowere very helpful at all times.

The librarians at the ROMprovided access to Hope's journals,and Charlotte Goodwin made copiesfor me. The figure was prepared withthe assistance of Brian Boyle in theROM Photography Department.

Ross D. James, Department of Ornithology, Royal Ontario Museum,100 Queen's Park, Toronto, Ontario M5S 2e6.

Red Crossbills Feedingat Mineral Sources

byRon Tozer

IntroductionThe habit of various carduelinefinches, including the Red Crossbill(Loxia curvirostra), to feed on sandand salt spread on road surfaces inwinter has been widely observeu andreported (e.g. Meade 1942; Lawrence1949, 1982; Bent 1968; Terres 1982).Very small stones (in the IIsand" ) areingested as a source of grit requiredfor digesting vegetable material in thegizzards of these granivorous birds(Lawrence 1949, Ehrlich et al. 1988).However, the apparent attraction tosalt is not as readily explained, eventhough it has been known for a longtime (e.g. Fisher 1888). Red Crossbillshave been observed feeding at a widevariety of seemingly unusual mineralsources, including: coal ashes onwhich salt had been thrown, soapydishwater, and snow discoloured by

ONTARIO BIRDS DECEMBER 1994

dog urine (Lawrence 1949); materialfrom cattle salt blocks (Marshall1940); salt spilled around ice creamfreezers (Dawson et al. 1965); and"the material left in salt porkbarrels" thrown outside lumbercamps (Bent 1968)! It has beensuggested that finches may beattempting "to satisfy a requirementfor some mineral that they do notobtain in sufficient quantity in theirfood" (Dawson et al. 1965) whenthey undertake such behaviour.

Observations of various feedingactivities by Red Crossbills recordedin Algonquin Provincial Parkincreased my interest in the subject,and so I undertook a search of theliterature to learn more about it. Thisarticle summarizes what I found, anddocuments some of the sightings fromthe Park.

SodiumSodium sources have been reportedas attractions for various birds,mammals, and even butterflies(Fraser 1985, Otis 1994). The birdsmay be attracted due to mineraldietary deficiencies, as previouslynoted. However, while the results ofexperiments on sodium chloridemetabolism in captive Red Crossbillsdid not "exclude this possibility", itwas concluded that "the ingestion ofsalt beyond that present in the food isunnecessary for maintenance ofsodium balance and apparent goodhealth by crossbills" even after theywere fed a vegetable diet 'Irelativelyhigh in potassium and low in sodium,for many months" (Dawson et al.1965). While we may not fullyunderstand why Red Crossbills areattracted to sodium sources, there aremany examples of its occurrence.

The most commonly observedsituation which attracts RedCrossbills, and other finches, tosodium involves birds on roads inwinter. De-icing salt (sodiumchloride), usually mixed with sand, iscommonly spread on roads and canbe available to finches in massivequantities. For example, Fraser (1985)estimated that sodiun1 chloride wasspread on the Trans-Canada Highwaynear Wawa, Ontario at a Ilrate of30-40 tonnes/km" each winter! RedCrossbills can be attracted to thisroad salt in large numbers; forinstance, I counted over 300 birdsalong a 20 knl stretch of Highway 60between the West Gate and FoundLake in Algonquin Park on 28February 1985. Also, due to theheavy winter application of sodiumchloride, roadside pools of stagnantwater can develop a sodium contentof 100 to 600 parts per million (ppm)

103

during the rest of the year (Fraser1985). Many of these pools andpuddles II are recharged with brine ateach rainfall and show little tendencyfor Na (sodium) levels to declineduring the summer" (Fraser 1985).Several finch species have beenrecorded Ilpecking in areas of dampsoil near the salty water" of thesepuddles (Fraser 1985). Pools of thistype in Algonquin Park are heavilyused by moose (Alces alces),especially during spring and earlysummer, and also attract RedCrossbills. For example, on 27September 1994, I observed fifteenindividuals appearing to ingest mudat a heavily trampled Ilmoosepuddle" along Highway 60 nearKearney Lake, Sproule Township. On11 November 1994, at another"moose puddle" beside the highwaynear Park (Long) Lake, FinlaysonTownship, I counted about 40 RedCrossbills feeding on the mud.Sixteen individuals were tightlyclustered on a small stump (whichappeared to have been previouslysubmerged in the muddy water),crawling over it and probing in itscrevices like a group of miniatureparrots!

Natural mineral springs ("licks")can contain "50-200 ppm Na plushigh levels of some other minerals"(Fraser 1985). These licks may have"14 to 120 times more sodium" thanother nearby non-lick areas (Fraser1980), and were recorded as majorattractions for birds such as PurpleFinch (Carpodacus purpureus) andPine Siskin (Carduelis pinus) in astudy at Sibley (now Sleeping Giant)Provincial Park (Fraser 1985). Speirs(1985) reported Red Crossbills"hopping about our feet at a salt lickat Montreal Falls by Lake Superior

VOLUME 12 NUMBER 3

104

one summer".Aquatic plants growing in shallow

lakes and ponds are another richsource of sodium, having up to 500times more sodium than leaves ofwoody plants (Fraser et al. 1980).Moose consume large quantities ofaquatic plants during summer,apparently because of a "specifichunger for Na" (Fraser 1980).Actively growing aquatic plants arenot a food source for finches, butthese plants may become anattraction after they die. RedCrossbills are frequently observedfeeding on exposed areas of "mud"(consisting of rotting aquatic plantsand their roots) at lakes and pondswhich attract moose in AlgonquinPark (e.g. six birds feeding on "mud"at Hobo Lake, Finlayson Township,on 29 July 1994, reported by DougTozer). I suspect these crossbills areattracted to the sodi urn released fromthe rotting aquatic vegetation at thesesites.

CalciumSeeds of Scots Pine (Pinus sylvestris)and Norway Spruce (Picea abies),which were eaten by crossbills inFinland, consisted of about 95 percent organic matter and 5 per centinorganic matter (Pulliainen 1972 J.Nearly 4 per cent of the latter wasnitrogen, while potassium,phosphorus, magnesium and calciumwere contained in the remaining 1per cent. Such findings may suggest acalcium (or other mineral) deficiencyin the diet of crossbills. A widevariety of crossbill feeding behaviourshave been reported which may bemanifestations of a hypothetical needfor calci um.

Meade (1942) reported largenumbers of White-winged Crossbills

ONTARIO BIRDS DECEMBER 1994

(L. leucoptera) and small numbers ofRed Crossbills that were ingesting amixture of calcium chloride and sandspread on a road in New York stateduring March. In this case it wastheorized that the attraction mighthave been the fine gravel, a cravingfor salt, and/or moisture gathered bythe calcium chloride.

Ingestion of supplementarycalci urn in the breeding season hasbeen documented for several birdspecies in northern areas (Ficken1989). For example, nestling LaplandLongspurs (Calcarius lapponicus) inAlaska "ate bones and egg shellfragments" (Seastedt and MacLean1971). Females might be attracted tosources of this mineral since"calcium needs for egg laying may beparticularly high" (Ficken 1989).Nethersole-Thompson (1975)observed female Scottish Crossbills(L. scotica) nibbling "a capercaillie's(Tetrao urogallus) skeleton" andcarrying "a mountain hare's bone tothe top of a pine", when breedingduring March, and concluded that"these birds evidently neededcalcium". Similarly, Baily (1953)reported that Red Crossbills hadsecured "scrapings from the bleachedbones of deer" during the breedingcycle.

Wood ash is rich in calcium, andits consumption has been reported forvarious birds, both during thebreeding period and at other seasons.Species reported eating ash include:Red Crossbills (Bent 1968); ParrotCrossbills (L. pytyopsittacus) andCommon Redpolls (Carduelis flammea)(Pulliainen et al. 1978 J; BorealChickadees (Parus hudsonicus) (Ficken1989); and even hummingbirds(Trochilidae) (des Lauriers 1994)! Inthe case of Boreal Chickadees, it was

shown that the ash where the birdsrepeatedly fed was much higher incalcium (2580 ppm) than nearby ash(600 ppm) where they never fed,suggesting an ability to detect richerconcentrations (Ficken 1989). Therehave been numerous observations ofRed Crossbills eating wood ash atcampfire sites in Algonquin Park (e.g.three males and two females atOpalescent Lake, Stratton Township,9 September 1963, reported by RussRutter).

Parrot Crossbills in Finland werereported eating the outer layer ofdecaying old pine logs, in the walls ofbuildings and lying on the ground."Nutrient analyses showed high ashand calcium contents in the woodsamples" (Pulliainen et al. 1978). Idid not find reports of this behaviour

105

by Red Crossbills, but it may welloccur.

Red Crossbills in Crater LakeNational Park, Oregon, wereobserved to feed on a powdery crust("probably made up of calcium saltsdissolved from the rock material")that formed on cliff faces of pumice(Aldrich 1939). The crossbills clung tothe cliff faces, placed their headssideways against the crust (whichwas loose and only one-sixteenth ofan inch thick), and licked it off withtheir tongues while holding their billsopen widely (Aldrich 1939). Thissame manner of feeding has beenrecorded at various man-mademineral sources, as noted below.

Dr. Alan Knox (British Birds 71:541) noted that "crossbills are wellknown for their habits of picking

Figure 1: Red Crossbills on chimney at Lake Travers, Algonquin Park.Photo by Michael Runtz.

VOLUME 12 NUMBER 3

106

Figure 2: Red Crossbills on chimney, feeding where a patch of material has beenremoved. Photo by Michael Runtz.

around chimney-stacks and eatingputty", but that while "thisbehaviour is very common" it is"surprisingly poorly documented".There are various reports (especiallyin the European literature) involvingcrossbills feeding on mortar andputty, apparently attracted to theircalcium carbonate content. Forinstance, Red Crossbills in Germanyappeared to eat soil from below astone wall, but analysis showed theywere consuming flakes of calciumcarbonate from the wall (Sainsbury1978). Scottish Crossbills were seento eat putty from windows (Watson1955, Nethersole-Thompson 1975).About 150 Red Crossbills werereported eating mortar "on the wallof a very dilapidated two storeyhouse" in Yugoslavia (Susie 1981).

ONTARIO BIRDS DECEMBER 1994

Nuttall (1907) wrote in 1891 that RedCrossbills in North America were"observed even to pick off the clayfrom the logs of the house". Baynes(1915) even claimed that RedCrossbills would come to the handfor pounded dried mortar!

The mortar and cement ofchimneys hold a special attraction forcrossbills. Scottish Crossbills havebeen reported feeding on the mortarof chimney-stacks (Nethersole-Thompson 1975, Bartlett 1976).Parrot Crossbills and CommonRedpolls were often seen eatingmortar from chimneys during a studyin northeastern Lapland (Pulliainen etal. 1978). William Brewster (1938)described numbers of Red Crossbillscoming early on October mornings to

cling to the sides, and cluster aboutthe top, of a brick chimney in theLake Umbagog region of Maine.Lawrence (1949), reporting on RedCrossbills at Pimisi Bay, Ontario,noted that they were often "seenclinging to our cobble stone chimney,pecking and eating the mortar" .

Red Crossbills consuming mortarand cement have been observed onnumerous occasions in AlgonquinPark. The most frequently used site(Figure 1) is the Turtle Club on LakeTravers, White Township, where fivestone chimneys are all that remainsof a log building erected in 1933(Runtz 1993). Red Crossbills appearto have eaten away patches ofmaterial on these chimneys to adepth of more than 2 cm in someplaces (Figure 2). Typical of sightingsthere were eight birds on 19 April1988, and 30 birds on 14 April 1989,reported by Michael Runtz. Similarly,I observed nine Red Crossbills eatingmortar from a wall of the"stonehouse" at Achray on GrandLake, Stratton Township, on 3 May1983. Red Crossbills allow a veryclose approach when eating mortar orcement, indicating their strongmotivation to feed on this material.

ConclusionA wide variety of unusual RedCrossbill feeding activities have beendocumented in the literature, andmany of these have been observed inAlgonquin Park. These behavioursappear to involve an attraction tominerals such as sodium and calcium,perhaps related to dietarydeficiencies. In contrast, I did notfind reports of White-wingedCrossbills undertaking such activities,apart from feeding at salted road sand(Benkman 1992). Could these

107

apparent behavioural differencesreflect dietary differences betweenthese two crossbill species? That andother questions will have to awaitfurther study.

I would be interested in hearingabout any unusual crossbill feedingactivities which readers may haveobserved or noted in the literature. Ihope this article will serve toencourage birders to learn moreabout unusual aspects of behaviouramong bird species that mayotherwise seem quite "familiar" tous. It can be a rewarding experience.

AcknowledgementsI wish to thank John Reynolds for hisvery valuable assistance in obtainingseveral references for this article atOxford University, and Jim Richardsfor access to his ornithologicallibrary. Michael Runtz kindlysupplied the photographs. Finally, Iappreciated the critical review of anearlier draft by Bill Crins, Ron'Pittaway, and Dan Strickland.

Literature citedAldrich, E. C. 1939. Notes on the salt-feeding

habits of the Red Crossbill. Condor 41:172-173.

Baily, A.L. 1953. The Red Crossbills inColorado. Part 2. 1952 observations of theRed Crossbills. Denver Museum of NaturalHistory Pictorial No.9: 33-63.

Bartlett, E. 1976. Crossbills feeding at chimney-stacks. British Birds 69: 312-313.

Baynes, E.H. 1915. Wild Bird Guests.E.P. Dutton, New York.

Benkman, C. W. 1992. White-winged Crossbill.In A. Poole, P. Stettenheim, and F. Gill(Editors). The Birds of North America.No. 27. Academy of Natural Sciences,Philadelphia; and American Ornithologists'Union, Washington, D.C.

VOLUME 12 NUMBER 3

108

Bent, A. C. {and collaborators}. 1968. LifeHistories of North American Cardinals,Grosbeaks, Buntings, Towhees, Finches,Sparrows and Allies. Part 1. United StatesNational Museum Bulletin 237. Washington,D.C.

Brewster, W. 1938. The birds of the LakeUmbagog region of Maine, compiled from thediaries and journals of William Brewsterby Ludlow Griscom. Bulletin of theMuseum of Comparative Zoology 66(4):525-620.

Dawson, W.R., V.H. Shoemaker, H.B. Tordoffand A. Borut. 1965. Observations onmetabolism of sodium chloride in the RedCrossbill. Auk 82: 606-623.

des Lauriers, J.R. 1994. Hummingbirds eatingashes. Auk 111: 755-756.

Ehrlich, P.R., D.S. Dobkin and D. Wheye.1988. The Birder's Handbook: A Field Guideto the Natural History of North AmericanBirds. Simon & Schuster, New York.

Ficken, M.S. 1989. Boreal Chickadees eat ashhigh in calcium. Wilson Bulletin 101:349-351.

Fisher, W.H. 1888. The American Crossbill,as to some of its habits and its fondness forsalt. Journal of the Cincinnati Society ofNatural History 10: 203-204.

Fraser, D. 1980. Moose and salt: a review ofrecent research in Ontario. Proceedings ofthe North American Moose Conference andWorkshop 16: 51-68.

Fraser, D. 1985. Mammals, birds, and butterfliesat sodium sources in northern Ontarioforests. Canadian Field-Naturalist 99:365-367.

Fraser, D., D. Arthur, J. K. Morton andB.K. Thompson. 1980. Aquatic feeding bymoose Alces alces in a Canadian lake.Holarctic Ecology 3: 218-223.

Lawrence, L. de K. 1949. The Red Crossbill atPimisi Bay, Ontario. Canadian Field-Naturalist 63: 147-160.

Lawrence, L. de K. 1982. A dash of salt.Nature Canada 11(4): 28*32.

Marshall, W.H. 1940. More notes on salt-feedingof Red Crossbills. Condor 42: 218-219.

Meade, G.M. 1942. Calcium chloride - a deathlure for crossbills. Auk 59: 439-440.

Nethersole-Thompson, D. 1975. Pine Crossbills.T. and A.D. Poyser, Berkhamsted, England.

Nuttall, T. 1907. A Popular Handbook of theBirds of Canada and the United States.Musson, Toronto.

Otis, G. W. 1994. Butterflies of AlgonquinProvincial Park. The Friends of AlgonquinPark, Whitney, Ontario.

Pulliainen, E. 1972. Summer nutrition ofcrossbills (Loxia pytyopsittacus, L. curvirostraand L. leucoptera) in northeastern Laplandin 1971. Annalen Zoologici Fennici 9: 28-31.

Pulliainen, E., T. Kallio and A.-M.Hallaksela. 1978. Eating of wood by ParrotCrossbills, Loxia pytyopsittacus, and Redpolls,Carduelis f/ammea. Aquilo Ser. Zool. 18:23-27.

Runtz, M. W.P. 1993. The Explorer's Guide toAlgonquin Park. Stoddart, Toronto.

Sainsbury, M. 1978. Crossbills I 'feeding" on soil.British Birds 71: 540-541.

Seastedt, T. R. and S. F. MacLean, Jr. 1971.Calcium supplements in the diet of nestlingLapland Longspurs Calcarius lapponicusnear Barrow, Alaska. Ibis 119: 531- 533.

Speirs, J.M. 1985. Birds of Ontario. Volume 2.Natural Heritage, Toronto.

Susie, U. 1~81. Red Crossbill (Loxiacurvirostra L. 1758) feeding on mortar in awall. Larus 33-35: 197-200.

Terres, J. K. 1982. The Audubon SocietyEncyclopedia of North American Birds.Alfred A. Knopf, New York.

Watson, A. 1955. Crossbills breeding inAberdeenshire. Scottish Naturalist 67:121-122.

Ron Tozer, R.R. 1, Dwight, Ontario POA IHO

ONTARIO BIRDS DECEMBER 1994