The status of Canada Goose Branta canadensis subspecies inGreenland

Three subspecies of the Canada Goose (Branta canadensis interior, B.c. parvipes and B.c. hutchinsii) have been reported from Greenland, where the species has increased dramatically as a breeding and summering bird in the last 30 years. We report results of catch data, new observations, re-examination of archive photographs and museum specimens that show the subspecies interior is the most common and widespread subspecies, which has been present in West Greenland since at least 1864 (predating the previous earliest record from 1976). Re-measurement of museum skins confirmed that all specimens of parvipes relate to individuals of the interior type, confirming parvipes has yet to be reported from Greenland. Observations and specimens also confirm the presence of the small B.c. hutchinsii as a rare summer visitor mainly between Disko Bay and Thule, with two recent records from East Greenland. Dansk Orn. Foren. Tidsskr. 106 (2012): 87-92 (Med et dansk resume: Status og forekomst af Canadagasens underarter i Gronland) 88 Canada Goose subspecies in Greenland A.D. and in the interior of the Sisimiut/Holsteinsborg District during c. 1200-1300 A.D. (Gotfredsen 2002), indicating that these were present and apparently more frequent in the past. However, the only authenticated record of Cackling Goose in Greenland was of a pair shot in Uummannaq district in 1914 (Salomonsen 1950). DB has also examined and verified a specimen shot in Sisimiut (68°N) before 1999 (in a private collection), and several field observations of Canada Geese both in Northwest Greenland (between Disko and Thule) and Northeast Greenland in recent decades include small Canada Geese (Bennike 1990, Best & Higgs 1990, Meltofte & Dinesen 2010, H. Ettrup in litt., J. Hansen pers. comm.), which were most likely Cackling Geese. The Lesser Canada Goose (subspecies parvipes) was reported in 1863 and 1864 from Qeqertarsuaq on Disko, where a pair stayed and probably bred (Salomonsen 1950). The male was shot and the specimen is now in the Zoological Museum of the University of Copenhagen (ZMUC No. 65265). Salomonsen subsequently assigned all larger Canada Geese collected in Greenland to subsp. parvipes (3 specimens in ZMUC), and a breeding pair observed on Disko Island in 1979 was also assigned to this subspecies (Pedersen 1984). The subspecies interior was reported for the first time from Greenland in 1976, when a pair was found nesting near Lille Narsaq south of Nuuk (Pedersen 1980). Since then the numbers of Canada Geese breeding and moulting in West Greenland have increased dramatically and breeding now takes place in the region between Paamiut at 62°N and Thule at 76°N (Frimer & Nielsen 1990, GWGS 1993, Boertmann 1994, Fox et al. 1996, Kristiansen et al. 1999, Boertmann & Egevang 2002, Fox & Glahder 2010, Rasmussen 2011). The Canada Geese which have contributed most to this increase have generally been ascribed to subspecies interior; confirmed for birds from around 67°N in central West Greenland by observations, capture, marking and measurement, satellite telemetry studies, genetic analysis and resightings and recoveries of marked individuals (Fox et al. 1996, Kristiansen et al. 1999, Scribner et al. 2003). The interior subspecies breeds from Ontario to northern Quebec and winters along the Atlantic coast of North America in Connecticut, New Jersey, New York, Pennsylvania, Delaware and Maryland (Mowbray et al. 2002). Given that the smaller forms of Canada Geese tend to breed furthest north in North America (Owen 1980, Mowbray et al. 2002), and that few Canada Geese in the northern part of the range in Greenland have been identified to subspecies (Fox et al. 2011, but see Best & Higgs 1990), it is logical to expect that small Canada Geese could make up a substantial amount of the Canada Geese recorded in the northern parts of West Greenland – between Disko Bay (69°N) and Thule (76°N). Recent results from a goose-catching programme and field observations in Northwest Greenland enabled us to gather more support for this hypothesis, which stimulated the re-examination of some old photos and re-measurements of the specimens kept in ZMUC. These investigations threw up some new and surprising interpretations of the Canada Goose subspecies occurring in Greenland, which we now present here. Materials and methods Twenty-four non-breeding Canada Geese were caught on 18 July 2008 in a drive net enclosure by a lake just north of the Thule Air Base, in Northwest Greenland (76.57°N 68.66°W) as part of a larger surveillance programme to screen a range of birds species in Greenland for Highly Pathogenic Avian Influenza (HPAI) under a cooperative agreement between the Ministry of Fisheries, Hunting and Agriculture (APNN) in Greenland, the Danish Department of Food and Agriculture, and the National Wildlife Disease Program of the United States Department of Agriculture. These geese were swabbed for HPAI and fitted with Copenhagen ZMUC metal rings, and linear measurements were taken of head and tarsus length (after Dzubin & Cooch 1992). These measurements were compared to a set of the same measurements from 99 individuals showing features characteristic of interior birds caught further south in Isunngua (67.08°N, 50.53°W) during 8 different drive net catches on different dates between 12 and 24 July 2008. Tarsus measurements taken during these more southerly catches were of tarsus bone (Dzubin & Cooch 1992) and so these measurements were inflated by an extra 21% to equilibrate to the tarsus length measurement based on calibrations of subsequently caught geese where both measurements were taken. A breeding record of Canada Geese of the subspecies parvipes in 1979 on Disko Island was approved by the Danish Rarity Committee based on photographs taken of the breeding bird and the eggs (Pedersen 1984). These photos were taken by KK and were reexamined by KK, DB and ADF in February 2012. The six specimens of Canada Geese obtained from Greenland that are kept in the ZMUC were also re-measured and examined in February 2012 by DB. 89 Canada Goose subspecies in Greenland