birds australia rarities committee unusual record report form golden... · 2013-01-26 · paulson d...

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Birds Australia Rarities Committee Unusual Record Report Form

Full Name: Tun Pin ONG (TPO, first observer) Nikolas K. HAASS (NKH) Graham BUCHAN (GB) David STOWE (DS)

Office Use

Address: Phone/e-mail TPO: 17 Betty Cuthbert Dr, Lidcombe, NSW 2141

Mobile: 04 04058118; [email protected]

NKH: 98 William St, Leichhardt, NSW 2040 Home: 02 95726392; mobile: 04 24668620; [email protected] Species Name: American Golden Plover (AGP, non-breeding adult)

Scientific Name: Pluvialis dominica

Date(s) and time(s) of observation: First sighted and photographed by TPO on 12 January 2009. At that time, the bird was in winter moult and was only suspected to be an AGP by its general greyer plumage. Subsequent observations were on: 16 Jan 2009 (TPO) 18 Jan 2009 (NKH) 23 Jan 2009 (TPO) 12 Feb 2009 (TPO) 22 Feb 2009 (TPO; bird started to display 4 primaries beyond longest tertial) 01 Mar 2009 (NKH) 08 Mar 2009 (TPO) 15 Mar 2009 (DS) 17 Mar 2009 (GB) 18 Mar 2009 (DS) 21 Mar 2009 (NKH) 28 Mar 2009 (TPO, with 15+ other birders) 05 Apr 2009: last reported sighting by Peter Higgins per birding-aus. The report authors as well as many other observers were able to recognize the bird as the same individual because of familiarization of its features and moult patterns.

How long did you watch the bird(s)? TPO and NKH each had spent at least 3 hours on each trip to the site. The bird was present on all the trips and was easily located. Numerous photographs were taken and observations were also made by others on many occasions especially after 22 Feb 2009 when the bird was observed to have acquired plumage highly suggestive of AGP.

First and last date of occurrence: The bird was initially detected by TPO on 12 Jan 2009. However, many reports of a Grey Plover by other observers in December 2008 may refer to this individual bird. The bird was last reported on 05 April 2009 by Peter Higgins via birding-aus.

Distance to bird: The bird and the accompanying Pacific Golden Plovers (PGP) were used to human presence and hence the authors and others were able to photograph and observe the bird at a distance of down to 10 metres.

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Site Location: Boat Harbour, southern part of the Kurnell Peninsula, Southeast Sydney, NSW. The site is a part of Boat Harbour Aquatic Reserve. Habitat: Tidal rock platform. The bird was mostly seen roosting on rocks above the highest tide line at the northeast end of the rock platform. When disturbed and also when the tide became lower, the bird, together with the PGPs, would shift and roost at the southwest end of the rock platform. The bird was roosting and feeding within the boundary of the rock platform during most trips. However, on 18 Jan 2009 afternoon as reported by NKH, the bird, together with other shorebirds, roosted at Cul-de-Sac rocks about further 300 m to the east of Boat Harbour, presumably due to heavy human disturbance on Sunday afternoon. Sighting conditions: The weather on 12 Jan, 16 Jan, 18 Jan, 23 Jan, 1 March, 8 March, 22 March, 28 March was fine with clear sky and very light wind. The weather on 12 Feb was windy with overcast conditions and occasional drizzle. The tide was very high in the morning. The weather on 22 Feb was bright but partly cloudy. During most trips to the site, the authors spent their time exclusively on observing and photographing the bird to collect as many data as possible for its identification. The exceptions were 12 Jan and 12 Feb, when TPO spent half of the time observing and photographing a juvenile Red Knot and a Great Knot, respectively. Optical aids used: TPO: Swarovski Spotting Scope HD80AT with 20-60x eye-piece. Occasionally this spotting scope was used in digiscoping which was coupled Nikon Coolpix 995 Digital Camera. When TPO was able to get closer to the bird, a DSLR camera was used instead (Canon 30D and 100-400mm IS Lens). NKH: Leica 12x50 BA; Zeiss Diascope 85*TL 20-60x; Canon 30D, 400mm 5.6 lens To your knowledge, is the species seen frequently at this site? No. To our knowledge the species has never been reported at the site before. The site is a regular roosting place for a number of shorebirds, including PGP, a closely related species to AGP. To date there are only two accepted records of AGP for Australia, those being a worn and faded juvenile seen and photographed at Byron Bay, NSW on 8 November 1994 (BARC case No. 189) and a well-photographed individual at the Dry Creek Saltfields, SA in November 2006 (BARC Case No. 529). Did you use a field guide? (or any other references for help with identification). Yes. References used during the observation and subsequently to prepare this report were: BEAMAN M & MADGE S (1998): The Handbook of Bird Identification for Europe and the Western Palearctic. Helm;

London. BAUER HG, BEZZEL E & FIEDLER W (2005): Kompendium der Vögel Mitteleuropas. Bd. 1: Nonpasseriformes. Aula;

Wiesbaden. CHANDLER, R.J. (1989): The Macmillan Field Guide to North Atlantic Shorebirds. London & Basingstoke CRAMP S & SIMMONS KEL (1985): Handbook of the Birds of Europe, the Middle East and North Africa. Vol. 3. Oxford

University Press; Oxford, New York. DELIN, H. & L. SVENSSON (1989): Der Kosmos-Vogelatlas. Stuttgart. DUNN JL, MORLAN J & WILDS CP (1987): Field identification of forms of Lesser Golden Plover, pp. 28-33 in Proc. 4th

Internatl. Identification Meeting (1986). International Birdwatching Center, Eilat, Israel. FRASER, P.A, M. J. ROGERS & THE RARITIES COMMITTEE (2007): Report on rare birds in Great Britain in 2005 Part I:

non passerines. British Birds 100: 16-61. GLUTZ VON BLOTZHEIM UN, BAUER KM & BEZZEL E (1977): Handbuch der Vögel Mitteleuropas. Bd. 7. Aula;

Wiesbaden. GOLLEY M & STODDART A (1991): Identification of American and Pacific Golden Plovers. Birding World: 4: 195-204 HARRIS, A., L. TUCKER, & K. VINICOMBE (1989): The Macmillan Field Guide to Bird Identification. - London. HAYMAN P, MARCHANT J, PRATER T (1986): Shorebirds. An Identification Guide to the Waders of the World. Helm;

London. DEL HOYO J, ELLIOTT A & SARGATAL J (1996): Handbook of the Birds of the World. Vol. 3: Hoatzin to Auks. Lynx;

Barcelona. JOHNSON OW & JOHNSON PM (2004a): Biometrics and field identification of Pacific and American Golden Plovers.

British Birds 97: 434-443.

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JOHNSON OW & JOHNSON PM (2004b): Morphometric features of Pacific and American Golden Plovers with comments on field identification. Wader Study Group Bull. 103: 42-49.

JONSSON L (1992): Birds of Europe: With North Africa and the Middle East. Helm; London. LEE, C.-T. & M. O’BRIEN (2011): Answers to the January Photo Quiz - Hard Shorebirds. Birding 43: 54-57. LEWINGTON I, ALSTRÖM P & COLSTON P (1991): A Field Guide to the Rare Birds of Britain and Europe. London. MARCHANT, S. & P.J. HIGGINS (eds) (1993). Handbook of Australian, New Zealand and Antarctic Birds. Volume 2:

Raptors to Lapwings. Melbourne. MESSAGE S & TAYLOR D (2005): Waders of Europe, Asia and North America. A Guide to Field Identification. Helm;

London. MLODINOW, S.G., & M. O’BRIEN (1996): America’s 100 Most Wanted Birds. Helena. MULLARNEY K, SVENSSON L, ZETTERSTRÖM D & GRANT P (1999): Collins Bird Guide. London. NATIONAL GEOGRAPHIC (4th ed. 2002): Field Guide to the Birds of North America. - Washington D.C. O’BRIEN M, CROSSLEY R & KARLSON K (2006): The Shorebird Guide. Houghton Mifflin; Boston, New York. PAULSON D (1993): Shorebirds of the Pacific Northwest. Vancouver. PAULSON D (2005): Shorebirds of North America: The Photographic Guide. London. PYLE P (2008): Identification Guide to North American Birds. Part II: Anatidae to Alcidae. ROSAIR D & COTTRIDGE D (1995): Photographic Guide to Waders of the World. Hamlyn SIBLEY D. (2000): The Sibley Guide to Birds. New York. We also examined numerous photographs of non-breeding AGP available on the web: http://www.fotosaves.com.ar/Charadriiformes/FotosCharadriiformes1.html#ChPampa Additional photos showing golden rump: http://www.fotosaves.com.ar/Charadriiformes/ChorloPampa3_Mag_27Oct2010_D.jpg http://uruguay-birder.tripod.com/sitebuildercontent/sitebuilderpictures/pluvialis_dominica.jpg Photos showing AGPs in flight and leg projection. Location: French Guiana Date: Oct 2008 http://www.oiseaux.net/photos/maxime.dechelle/pluvier.bronze.4.html#monde Were other observers present? Do any of the other observers disagree with your identification? Initial sighting and photographs on 12 January 2009 did not show any structural features that can be reliably identified as an AGP because the bird was in winter moult. The outermost primaries were badly worn and the fresh tertials were not fully grown at that stage. During this time, the bird was treated tentatively as a possible AGP based on few subtle field characteristics. The bird was first observed to show 4 exposed primaries on 22 Feb 2009. Ever since then, the bird had been observed by a number of birders from around Sydney and interstate, including Peter Abbott, Max & Lloyd Breckenridge, John Duranti, Eric Finley, Peter Higgins, Rob Hynson, Jon Irvine, Dick Jenkin, Noel Luff, Alistair McKeough, Martyn Moffat, Troy Mutton, Alan Rogers, Ashwin Rudder, Colin Scouler, Dejan Stojanovic, Alan Stuart, Bob Way, Ed Williams and many others. Simon Blanchflower, Keith Brandwood, Mike Carter, Rohan Clarke, Jeff Davies, Phil Hansbro, Tobias Hayashi, Dan Mantle, Mick Roderick, Danny Rogers, Phil Straw and others were involved in a lively discussion. In addition a number of overseas birders commented on the photos and agreed with the identification AGP: Paul Lehman, USA; Michael O’Brien, USA; George Armistead, USA; Killian Mullarney, Ireland; Arne Torkler, Germany. Despite the initial scepticism of a number of birders (including the authors themselves), later during its stay most birders agreed with the identification as a PGP, based on new features showing during moult progression. How confident are you of your identification? 100% - see “Physical description” and “Elimination of other species” below. Our research has confirmed the identification as a non-breeding adult AGP that looks similar to non-breeding AGP found in South America at this time of the year. Other details: e.g. Do you have historical and or anecdotal information/comments relating to the prior occurrence/status of the species within or near this location? No. The site has been surveyed regularly by a number of local birders for many years and none had reported an AGP or a plover that looked like an AGP. There was a report of a Grey Plover in December 2008, which the authors had never observed throughout their visits to the site during January to March 2009. This may suggest that this AGP may have been misidentified as that Grey Plover reported in late 2008.

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Physical description of the bird: The bird was first located and photographed at close range (approximately 8 meters) on 12 January 2009. TPO’s initial intention to visit the site was to look for a Wandering Tattler that had been reported earlier but it was not present then (and was never sighted ever since at the site by TPO in all his subsequent visits). With no Wandering Tattler in sight, TPO had to divert his attention to other common birds and started to digiscope a lone Red Knot, PGPs, Red-necked Stints and Ruddy Turnstones. While TPO was digiscoping a standing PGP, a greyer Pluvialis Plover walked into the frame. Due to its greyer and duller upperparts, the bird was initially identified by TPO as a greyer variant of PGP among other 12+ typical PGPs. TPO immediately ruled out a Grey Plover because of his previous experience with Grey Plover in Malaysia. More importantly, TPO has gained his intimate familiarity with Grey Plover by his very close range sighting of Grey Plover with GB at nearby Penrhyn Estuary, Port Botany, Sydney. The larger Grey Plover has a strong bill and less elegant look. The difference between Grey Plover and PGP would be very obvious if they had been side by side. Its plainer throat and chest with no spots as well as its shorter legs immediately gave TPO the impression that this could be an AGP. Although TPO had no previous experience with AGP, a sighting of a possible AGP reported by GB during 15-19 Sept 2006 had generated TPO’s great interest in AGP, although the sighting did not lead to a positive identification at that time. TPO had read the papers of JOHNSON & JOHNSON (2004a, b) at that time and had some idea what an AGP should look like.

Figure 1. Boat Harbour: Non-breeding American Golden Plover (left). Note the bird has grey white throat and chest with slightly scalloped pattern but without any dark streaks or spots. The bird still retained its worn primaries, which at this stage cannot be reliably used for identification of AGP/PGP based on its primary/tertial structure (Photo: Tun-Pin Ong, 12/01/2009).

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Following are the features that were indicative of AGP during the first sighting on 12 Jan 2009. 1) General greyer tone in plumage, except for the rump, which has relatively rich yellow spots. 2) Grey white supercilium, with no hints of yellow in the head, and neck. 3) Light grey throat and belly, with faintly scalloped feathers, and no hints of yellow nor dark streaking or

markings. 4) Shorter tibia, especially at rest or roosting. 5) More angular bill, compared to accompanying PGPs whose bills were more tapered, giving the

impression of a more bulbous tip. Note this difference was very subtle and was only observed side by side with a typical PGP.

Figure 2. Boat Harbour: Non-breeding American Golden Plover (left). Note the bird has shorter tibia and slightly different bill shape. As the birds are in moult, the primaries and tertials provide no clues and the primary projection appeared the same as the typical PGP on the right. The bird still retained its outermost worn primaries. On 16 Jan 2009, 4 days later, it had shed these worn outermost primaries. (Photo: Tun-Pin Ong, 12/01/2009)

Figure 3. Boat Harbour: Non-breeding American Golden Plover (Right). Note the bird’s shorter tibia and slightly different bill shape. Both the tertials and primaries have developed considerably compared to a month ago. However, at this stage, there were still 3 exposed primaries from the longest tertial. (Photo: Tun-Pin Ong, 12/02/2009)

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TPO understood at the time of observation that a number of reports of AGP in the past had been rejected due to the bird being notoriously hard to identify positively. Hence he had taken as many photos as he could of this particular bird even knowing that the identification may not be conclusive as the bird was in moult, particularly the primaries were heavily worn. TPO still paid subsequent visits to Boat Harbour to monitor on the progress of the bird’s moult. He also kept a number of birders in the loop by e-mail, hoping to get some additional advice on the bird’s ID. Knowing that the bird was still moulting and had not displayed 4 exposed primaries in its primary projection, it was difficult to identify it positively as an AGP, based on available literature. On Thu 12 Feb 2009, the bird had developed further on its tertials. And at the same time the primaries still had not developed significantly. Hence the number of exposed primaries was still 3, actually barely 3. At this stage, TPO had almost given up and called it just an aberrant greyish PGP. At this stage one could not deduce whether the primaries would grow further. If this indeed had been a PGP, its tertials would still develop even longer! However, on Sun 22 Feb 2009 morning, it was found that the bird had developed its primaries considerably. And very importantly, for the first time, the bird had shown 4 primaries beyond the longest tertial, although the 4th primary, P7, had barely passed beyond the longest tertial. TPO managed to take photographs of the bird on its left side to display the primary projection (Fig. 4). TPO also ensured he had confirmed by field observation that the same 4th primary projection had also appeared on the right side. Unfortunately he did not manage to get any photographic evidence of this field mark on the bird’s right side.

Figure 4. Boat Harbour: Non-breeding American Golden Plover. TPO had noticed for the first time that the bird exhibited a key feature for AGP, i.e. 4 exposed primaries beyond the longest tertial. Measurements taken on the photo as labelled (A,B,C,D) were used to deduce the actual length. Refer to table 1 & 2. (Photo: Tun-Pin Ong, 22/02/2009)

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Biotic Measurements Estimated from Boat Harbour Plover (Based on Figure 4) As the Boat Harbour bird was not held in hand, conventional measurements were not taken. However, these biotic measurements can still be deduced if bill length is used as a common reference between the Boat Harbour bird and measurement in literature. For example, For assumption of dominica,

Primary Projection deduced (mm), PP = BLdominica x C / A , Where

BLdominica is the mean bill length of dominica from literature, i.e. 22.8mm A is the measurement of bill length on the photo

C is the measurement of Primary Projection on the photo

For assumption of fulva, Primary Projection deduced (mm), PP = BLfulva x C / A , Where

BLfulva is the mean bill length of fulva from literature, i.e. 24.3mm A is the measurement of bill length on the photo

C is the measurement of Primary Projection on the photo

Table 1a – Estimated measurement of the Boat Harbour plover for assumption of dominica Measurement taken from photo Figure 4.

Label in Fig 4

Arbitrary measurement, M

Input Bill Length (mm)

Deduced Measurement (mm) = BL x M/MBL

Bill length A 70 (=MBL) BL = 22.8 22.8 Fixed Input Bill base to eye edge B 64 20.8 =(22.8x64/70) Primary projection C 86 28.0 =(22.8x86/70) Primary extension (wing projection) D 57 18.6 =(22.8x57/70) Distance btw longest primaries E (not

labelled) 17 5.5 =(22.8x17/70)

Note: The biotic measurements are calculated from Fig. 4 by taking measurement as labelled A, B, C, D, E. The bill length is assumed to be 22.8mm [The mean bill length for AGP is 22.8mm, based on JOHNSON & JOHNSON (2004b, p.43 Table 1)], hence other biotic measurements can be deduced as illustrated in table above using the ratio. Table 1b – Estimated measurement of the Boat Harbour plover for assumption of fulva Measurement taken from photo Figure 4.

Label in Fig 4

Arbitrary measurement, M

Input Bill Length (mm)

Deduced Measurement (mm) = BL x M/MBL

Bill length A 70 (=MBL) BL = 24.3 24.3 Fixed Input Bill base to eye edge B 64 22.2 =(24.3x64/70) Primary projection C 86 29.9 =(24.3x86/70) Primary extension (wing projection) D 57 19.8 =(24.3x57/70) Distance btw longest primaries E (not

labelled) 17 5.9 =(24.3x17/70)

Note: The biotic measurements are calculated from Fig. 4 by taking measurement as labelled A, B, C, D, E. The bill length is assumed to be 24.3mm [The mean bill length for PGP is 24.3mm, based on JOHNSON & JOHNSON (2004b, p.43 Table 1)], hence other biotic measurements can be deduced as illustrated in table above using the ratio. The calculated values in column 5 were then transferred to Table 2 to compare whether the data support fulva or dominica.

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Table 2 – Comparison of measurements taken from the Boat Harbour plover against measurement of fulva and dominica in literature. Note: Data shown in shaded boxes are data copied directly from literature for comparison JOHNSON & JOHNSON (2004a, p.439 Table2)

Comparison Features

Pacific Golden Plover (P. fulva)

American Golden Plover (P. dominica)

Boat Harbour bird as PGP

Boat Harbor bird AGP

Support to ID

1. Primary tips exposed beyond longest tertial

2-3 in all birds (n=44)

4-5 in all birds (n=23)

4 ✗Out-of-range 4 ✔ Strongly AGP

2. Primary projection past end of the tail

0-9 mm (n=50) 12-22 mm (n=34) D =19.8 ✗ Out-of-range

D = 18.6 ✔ Strongly AGP

3. Distance between tips of two longest primaries

2.7 ± 1.7 (0-6.0, 44)

5.0 ± 1.7 (0.5-9.0, 23)

E = 5.9 ✓ Extremely long for a PGP

E = 5.5 ✓ AGP

4. Length of unfeathered tibia

20.4 ± 1.8 (17.6-24.1, 37)

16.7 ± 1.7 (14.8-21.2, 23)

Not measured but always shorter than other PGPs

Not measured but always shorter than other PGPs

AGP

6. Percentage with bill projecting beyond rear edge of eye

91% (40 of 44) 62% (18 of 29) Bill projected beyond rear edge of eye ✓

Bill projected beyond rear edge of eye ✓

both AGP/PGP

7. Bill projection beyond eye

2.6 ± 1.2 (0.2-5.2, 40)

1.6 ± 0.9 (0.3-3.7, 18)

2.1 mm(A-B) ✓

2 mm(A-B) ✓ both AGP/PGP

8. Base of bill to rear edge of eye

21.4 ± 0.9 (19.0-23.1, 44)

22.0 ± 0.9 (20.0-24.0, 29)

22.2 mm(B) ✓ 20.8 mm (B) ✓

both AGP/PGP

9. Tertial length relative to tail length

Tertials extend to distal third of tail, falling at or near tail tip in most

Variable, from half to distal third of tail

Half of tail (as from photo 4) ✗ Out-of-range

Half of tail (as from photo 4) ✓

AGP

Ref: JOHNSON & JOHNSON (2004a, p.439) “Table 2. Features associated with the field identification of Pacific Pluvialis fulva and American Golden Plovers P. dominica. Data show mean in mm ± SD (range, n) where possible.”

Deduction from the measurement comparison in Tables 1a, 1b, 2: 1. Primary tips exposed beyond longest tertial. This is one of the major features that determines dominica from fulva where AGP has 4-5 exposed primaries and PGP has only 2-3. However careful considerations are required as this feature is meaningless for birds in worn or moulting stage. The Boat Harbour bird had been observed for the period from mid Jan to as late as early Apr (2 ½ months) where both tertials and primaries were observed to develop progressively and had attained relatively stable stage where 4 exposed primaries were observed since 22 Feb 2009. 2. Primary projection. The primary projection of the Boat Harbour bird (calculated as 18.6 mm based on dominica assumption) fits within the range for dominica (12-22 mm). If the Boat Harbour bird were to be treated as a fulva, then the calculated primary projection of 19.8 mm would be too long and completely out of range for fulva (0-9 mm). Hence our calculated primary projection measurements favour strongly dominica. It is worthwhile to note that there is NO overlap of primary projection dimension between these two forms according to literature (0-9 mm for fulva and 12-22 for dominica). 3. Distance between P9 and P10. The measurement of the Boat Harbour bird deduced for dominica (5.5 mm) fits the measurement for dominica according to the literature (0.5-9.0 mm). If the Boat Harbour bird were to be treated as a fulva, then the calculated distance between P9 and P10 of 5.9 mm would only fit an extreme case for fulva (0.0-6.0 mm, JOHNSON & JOHNSON 2004a). Note that use of distance between P9 and P10 to distinguish between fulva and dominica is not as convincing as primary projection. This is because inherently there is an overlap of measurements between these two species. Despite this, the outcome of this particular dimension still favours dominica.

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Figure 5: Four primary tips visible beyond folded tertials. Note this was the first time that the bird was observed to have 4 exposed primary tips. (Photo: Tun-Pin Ong, 22/02/2009)

Figure 6: Roosting Boat Harbour Golden Plover. Note the exposed 4 primaries. GB used this photo for computing the bird’s primary projection and P9-P10 distance (Ref AGP_0245e.jpg used in GB’s measurement analysis). See calculations in tables 3 & 4 below. (Photo: David Stowe, 18/03/2009)

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Biotic Measurements Estimated from Boat Harbour Plover (Based on Figure 6) Note: The following calculation and measurement data in Tables 3, 4, 5 were provided by GB and compiled by TPO. Table 3. Input Data # Item Parameter Note 1 Photograph AGP_0245e.jpg (or Fig. 6) Photo courtesy of David Stowe 2 Bill Length 14 This is an arbitrary measurement

taken from photos and is used for calculating ratio. The value does not correspond to actual measurement.

3 Primary Projection Beyond Tail

8 This is an arbitrary measurement taken from photos and is used for calculating ratio. The value does not correspond to actual measurement.

4 Ratio (R1) = Primary Projection / Bill Length

0.571 (= 8 / 14) This ratio will used to deduce actual measurement in next tables and then compare whether it fits closer to fulva or dominica.

5 Distance between 2 longest primaries at rest (P9 to P10)

4 This is an arbitrary measurement taken from photos and is used for calculating ratio. The value does not correspond to actual measurement

6 Ratio (R2) = Distance btw P9 and P10 / Bill Length


Table 4. Using bill length obtained from JOHNSON & JOHNSON (2004a, Table 1, Pg 435) and measurement from Fig. 6 to deduce primary projection and distance between P9 and P10. Methods: 1) Tabulate bill lengths available from JOHNSON & JOHNSON (2004a, “J&J”) for both fulva and dominica (Table 4a) 2) Using the bill length in Table 4a, and bill/primary project ratio for Boat Harbour bird, deduce the Primary

Projection (mm) for Boat Harbour bird. Compare the values with measurements in literature. (Table 4b) 3) Using the bill length in Table 4a, and bill/P9P10 distance ratio for Boat Harbour bird, deduce the Distance

between P9 and P10 (mm) for Boat Harbour bird. Compare the values with measurements in literature (Table 4c) Table 4a

Bill Length (mm) as obtained from J&J

Table 4b Primary Projection (mm) deduced from bill length and ratio R1

Compare Primary Projection (mm) with J&J

fulva A

dominica B

fulva A x R1

dominica B x R1

fulva

dominica

Min 20.2 21.0 Min 11.5 ✗ 12.0 ✔ 0 12 Max 27.6 24.7 Max 15.8 ✗ 14.1 ✔ 9 22 Mean 24.3 22.8 Mean 13.9 ✗ 13.3 ✔ Table 4c Distance Between P9 and

P10 (mm) deduced from bill length and ratio R2

Compare Distance between (mm) P9 and P10 with J&J

fulva A x R2

dominica B x R2

fulva 2.7±1.7

dominica 5.0±1.7

Min 5.8 ✔ 6.0 ✔ 0.0 0.5 Max 7.9 ✗ 7.1 ✔ 6.0 9.0 Mean 6.9 ✗ 6.5 ✔ 2.7 5.0 SD 1.7 1.7

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Deduction from the measurement comparision in Tables 4a, 4b, 4c: Primary projection. The primary projection of the Boat Harbour bird (calculated as 12-14.1 mm based on dominica assumption) fits within the range for dominica (12-22 mm). If the Boat Harbour bird were to be treated as a fulva, then the calculated primary projection of 11.5-15.8 mm would be too long and completely out of range for fulva (0-9 mm). Hence the primary projection measurements as computed with this method also favour strongly dominica. As mentioned above, there is NO overlap of primary projection dimension between these two forms according to literature (0-9 mm for fulva and 12-22 for dominica). Distance between P9 and P10. The measurement of the Boat Harbour bird deduced for dominica (6.0-7.1 mm) fits within the range for dominica (0.5-9.0 mm). In fact, by taking the mean value of 6.5 mm for the Boat Harbour bird, this further rules out fulva (0.0-6.0 mm) as it exceeds the maximum measurement of 6 mm for fulva. If the Boat Harbour bird were to be treated as a fulva, then the calculated distance between P9 and P10 of 5.8-7.9mm would only fit into the range for fulva (0.0-6.0 mm) if the bill is shortest among fulva. In other words, if the Boat Harbour bird was a fulva then it would be a fulva with very short bill that has very long distance between P9 and P10. Note that use of distance between P9 and P10 to distinguish between fulva and dominica is not as convincing as primary projection. This is because inherently there is an overlap of measurements between these two forms. Despite this, the outcome of this particular dimension still favours dominica.

Figure 7: Foraging Boat Harbour Golden Plover. GB used this photo for computing the bird’s tibiae (Ref AGP_0029e.jpg). See calculations in tables 5, 5a and 5b below. (Photo: David Stowe, 15/03/2009)

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Table 5. Input Data # Item Parameter Note 1 Photograph AGP_0029e.jpg (or Fig. 7) Photo courtesy of David Stowe 2 Bill Length 14 This is an arbitrary measurement

taken from photos and is used for calculating ratio. The value does not correspond to absolute measurement.

3 Unfeathered Tibia 10 This is an arbitrary measurement taken from photos and is used for calculating ratio. The value does not correspond to absolute measurement.

4 Ratio (R3) = Unfeathered Tibia / Bill Length


Table 5a

Bill Length (mm) as obtained from J&J

Table 5b Length of unfeathered tibia (mm) deduced from bill length and ratio R3

Unfeathered tibia (mm) from J&J

Fulva A

dominica B

fulva A x R3

dominica B x R3

fulva

dominica

Min 20.2 21.0 Min 14.4 ✗ 15.0 ✓ 17.6 14.8 Max 27.6 24.7 Max 19.7 ✓

17.6 ✓ 24.1 21.2

Mean 24.3 22.8 Mean 17.4 ✗ 16.3 ✓ 20.4 16.7 SD SD 1.8 1.7 Deduction from the measurement comparision in Tables 5: Length of unfeathered tibia. The unfeathered tibia for the Boat Harbour bird (calculated as 15.0-17.6 mm based on dominica assumption) fits within the range for dominica (14.8-21.2 mm). If the Boat Harbour bird were to be treated as a fulva, then the calculated length of unfeathered tibia of 14.4-19.7 mm would only fit into the range for fulva (17.6-24.1 mm) if the bill is longest among fulva. In other words, if the Boat Harbour bird was a fulva then it would be a fulva with very long bill and has relatively very short unfeathered tibia. Note that use of unfeathered tibia to distinguish between fulva and dominica is not as convincing as primary projection. This is because inherently there is an overlap of measurements between these two forms. Despite this, the outcome of this particular dimension still favours as a typical dominica. It only favours fulva if this is an individual with very large bill with very short unfeathered tibia. (ii) Toe projection in flight In addition to the structural and plumage features discussed above, it is stated by DMW (1987, p. 29) that fulva is smaller and slimmer than dominica but has a proportionally longer bill and slightly longer legs. They also note that these differences are difficult to use with precision in the field. However, MULLARNEY et. al (1999, p. 134) describe dominica as on average slightly larger and slimmer-bodied, longer-winged and shorter legs with toes that usually do not project beyond the tail tip in flight. Consequently, it is generally accepted by most field guides that the feet of fulva protrude significantly beyond the tail in flight while those of dominica do not. At best there is a slight toe projection in dominica. The position of the feet of the Boat Harbour plover in flight has been captured well in Figures 7 and 8 below (photo courtesy of David Stowe).

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Figure 8. Toe projection in flight. Note that the toes do not project beyond the tail tip. (Photo: David Stowe, 15/03/2009)

Figure 9. Toe projection in flight – Boat Harbour bird (left) in contrast to a typical fulva (right). Note that the toe of the typical fulva projects well beyond the tail tip. (Photo: David Stowe, 15/03/2009) (iii) Proportional bill length and leg length. DMW (1987, p. 29) also states that fulva has a proportionally longer bill and slightly longer legs. Note the word ‘proportional’ used. This is because dominica, being slightly larger and the measurement of bill and legs between 2 forms in absolute terms may not be significantly distinct. However, in proportion to the head and body, the Boat Harbour plover showed consistently shorter bill and shorter tibia.

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Figure 10: Comparison of proportional length of bill and legs. Boat Harbour plover dominica (left) and typical fulva (right). (Note at the time of this photo was taken, the Boat Harbour bird on the left had not completed its feather moult yet and hence the short fresh primaries had not shown any diagnostic features of dominica.) (Photo: Tun-Pin Ong, 23/01/2009) (iv) Overall greyer plumage with rich yellow-spotted rump The Boat Harbour plover showed consistently greyer plumage and lack of yellow with other typical Pacific Golden Plover. In contrast to the other typical PGP around it, there was hardly any hint of yellow on its face, neck and breast. There were some little yellow speckles on the crown and the mantle but even these parts were far duller than other PGPs it was associating with. However, there were rich yellow spots confined to the rump, making this the only area in the whole body where significant yellow plumage can be found. This feature is consistent with American Golden Plover in winter plumage as described in DUNN (1987, p.29) where “dominica is much grayer (except on the rump)”. Other subtle features mentioned in the last two paragraphs in DUNN (1987, p.29) fit the Boat Harbour plover into American Golden Plover, whereas other fulva features in the text match the typical PGPs at Boat Harbour, with the exception of no yellow-tinged supercilium observed on Boat Harbour bird and the degree of the streakiness cannot be clearly discerned: “…..In fulva the entire facial area is usually suffused with yellow. In dominica yellow is usually absent on the face or confined to a slight wash on the supercilium. Dominica has a solid dark area of variable width from just in front of the eye through the ear-coverts. Fulva has a pale area immediately around the eye, and the ear-coverts tend to form a distinct post-ocular spot separated from the eye. On fulva the nape is paler, less streaked, and much yellower than on dominica. The cap and mantle of dominica are darker with smaller gold spots, giving it a better-defined cap and darker area on the upper back. Dominica usually lacks yellow on the nape except for a small amount near the top on individuals with a yellow-tinged supercilium.” DUNN et al. (1987)

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Figure 11: Underwing pattern, overall greyer plumage and rich yellow-spotted rump. Boat Harbour Plover (right) with Pacific Golden Plovers. (Photo: Tun-Pin Ong, 22/02/2009)

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Figure 12: Partial upperwing pattern, rump with rich yellow spots, and tail feathers. Boat Harbour Plover about to fly off, with part of its right wing obscured by a flying Ruddy Turnstone. (Photo: Tun-Pin Ong, 28/03/2009)

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Figure 13. The Boat Harbour bird is featured on the left with 2 fulva in the middle and right for comparison. The 4 exposed primaries of dominica can be noticed on the Boat Harbour bird. In this photo, the Boat Harbour bird appears to be slightly larger than the other two typical fulva individuals. The birds are in more alert condition and hence the plumage becomes less fluffy for the Boat Harbour bird and the upper thigh becomes more exposed and longer. Despite exhibiting longer upper thigh in this photo, the Boat Harbour bird still displays relatively shorter upper thighs than the fulva, albeit only marginally this time. It is worthwhile to mention that the fulva on the right appears to have also 4 exposed primaries at first glance. However there is a single long tertial covering the primaries (only shadow is seen in this photo). Therefore, this photo does not disprove that 4 exposed primaries beyond the longest tertial has not been observed in any fulva so far. (Photo: Nikolas Haass, 01/03/2009)

Figure 14: (Photo: Nikolas Haass, 01/03/2009)

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Figure 16: Boat Harbour plover is at the foreground in the middle. Note the pure white supercilium. Also note that all four PGPs have distinct post-ocular spot at ear-coverts, which is absent on this Boat Harbour plover. (Photo: Nikolas Haass, 01/03/2009)

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(v) Underwing pattern

Figure 20: Underwing pattern. (Photo: Tun Pin ONG, 12/02/2009) (vi) Complete moult into Non-breeding plumage The bird had almost completely attained its non-breeding plumage in late February to March. In fact, the other typical PGPs had even started to moult into partial breeding plumage. Throughout the authors’ observations from January to March 2009, the Boat Harbour plover had transformed its plumage from shedding worn primaries to attaining fresh long tertials and primaries. Once the growth of the tertials and primaries had stabilised (since 22nd February, 2009) the “classic AGP features” became apparent, namely the projection of four primaries beyond the tertials and the long wing projection, indicating that the bird had completed its non-breeding moult.

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(vii) Calls: TPO heard calls that matched AGP rather than PGP. NKH played both AGP and PGP calls (21/03/2009) but did not get a significant response from any of the present GPs. Other species with which you think it might be confused and how these were eliminated? Elimination of European Golden Plover P. apricaria: Larger, heavier (intermediate between Grey and AGP/PGP); rounder body; shorter legs; relatively even smaller bill; white underwings. Elimination of Grey Plover P. squatarola: Conspicuously larger/heavier; chunkier; large-headed; heavy-billed; black axillaries; white rump. Elimination of Pacific Golden Plover P. fulva : [1] There were four primary tips visible beyond the tertials and all tertials were present and freshly moulted. (The bird was monitored for an extensive period of time, from January to March. Both primaries and tertials were observed to grow and stabilize with four primary tips visible for at least 3 weeks since 22 Feb 2009) [2] Using two different calculation methods, the primary extension beyond the tail (wing projection) fell within the range of dominica and was out of range for fulva. [3] Further field marks (namely distance between p10 and p9, length of tibia, toe projection, relative leg length, relative bill length and overall colouration) matched dominica better than fulva. Elimination of hybrid dominica x fulva When considering the possibility of a hybrid Dunn, Morlan and Wilds (1987, p. 33) note: “It is particularly important to be able to distinguish true hybrids from extreme variants within a population. There is enough variation in the plumages of these forms to make confirmation of hybridization a difficult and controversial subject. We urge that intermediate birds should not be interpreted as hybrids until the variability of known plumage characters become clear. We also suggest great caution in identifying any individual that does not show the typical pattern of one type or other, particularly in the case of out-of-range birds.” (DUNN et al. 1987) Nevertheless, an intermediate bird was seen and heard in October 2004 in Cape May, New Jersey, USA and published as a ‘presumed American x Pacific Golden Plover Hybrid (O’BRIEN et al. 2006). Given that the characteristics of the Boat Harbour bird place it somewhere in the middle of the distribution of characteristics typical of dominica (4 primary tips, wing projection, toe projection in flight, leg, size, general greyer plumage except rump) we believe that there are no objective grounds for classifying it as a hybrid fulva x dominica. Summary: Although there are four Pluvialis species, the only realistic candidates for the Boat Harbour bird would be (1) AGP, (2) aberrant PGP or (3) a hybrid, as European Golden and Grey Plover are easily eliminated (see above). Taken together the data collected over the observation period of almost three month as presented on the previous 22 pages of this report, we positively identified the Boat Harbour bird as a non-breeding adult American Golden Plover Pluvialis dominica.

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What experience have you had with the species in question? TPO had no previous experience with AGP. During 15-19 Sept 2006, Sydney birder GB had reported sighting of a possible AGP at Penrhyn Esturary, Port Botany, NSW. (http://61.69.13.21/home/birding/plover.html). Although the sighting did not lead to a positive identification at that time, this has created a great deal of interests among birders in Australia. Hence, TPO had some ideas on top of his head some indicative features of AGP such as overall greyer plumage, slightly bigger size, slightly shorter legs during his first encounter of the bird. NKH has experience with all Pluvialis. He saw many EGPs in Europe (where NKH lived until 2003) and many Grey Plovers all around the world. Importantly, he observed many AGPs in the USA (mostly between 2003 and 2007, when NKH lived in the USA, but also during several previous visits since 1985), and one adult male AGP in breeding plumage in Denmark in May 1999 (ENEVOLDSEN & HAASS 2000). Finally, he saw many PGPs in Australia, Indonesia, Thailand, India, Hawaii, Alaska, California, one adult PGP in breeding plumage in Schleswig-Holstein, Germany, in July 2000 (SCHLORF, GOEDELT, HAASS et al. 2006) and another adult PGP in breeding plumage in Friesland, Netherlands, in July 2002 (LEURS, JANSEN, HAASS et al. 2003). ENEVOLDSEN E & HAASS NK (2000): Amerikansk Hjejle Pluvialis dominica. In: THORUP K & HAANING NIELSEN H

(2000): Sjældne fugle i Danmark og Grønland i 1999. Dansk Orn. Foren. Tidsskr. 94: 157-170. LEURS W, JANSEN JJFJ, HAASS NK et al. (2003): Pacific Golden Plover / Aziatische Goudplevier Pluvialis fulva. In:

VAN DER VLIET RE, VAN DER LAAN J & CDNA (2003): Rare birds in the Netherlands in 2002. http://www.dutchbirding.nl/cdna.php?id=25

SCHLORF M, GOEDELT J, HAASS NK et al. (2006): Tundra-Goldregenpfeifer Pluvialis fulva. In: DEUTSCHE SELTENHEITENKOMMISSION (2006): Seltene Vogelarten in Deutschland 2000. Limicola 20: 281-353.

Interestingly, none of the authors had seen AGPs in their wintering grounds before. Hence the initial confusion and scepticism. The study of photographs of wintering AGPs in South America (see above-listed websites) helped to close that gap of experience. Was the description written from notes and/or sketches made (tick box): x during the observation or; o shortly after the observation or; o from memory; x with the aid of the photographs Please indicate supportive evidence available. Was the bird: photographed, ü taped or o video taped? If yes to any of these, by whom? Unless specifically stated, all photos are provided by Tun Pin Ong, Nikolas Haass and David Stowe, where indicated. Signature:

(Nikolas K. Haass on behalf of the co-authors Tun Pin Ong, Graham Buchan & David Stowe)

Date: 26/12/2012

Please forward all material to: The Secretary, Birds Australia Rarities Committee, Birds Australia HQ, Riverside Road, East Hawthorn, VIC 3123

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