DDiissttrriibbuuttiioonnaannddIIddeennttiifificcaattiioonnooff CCaacckklliinnggGGoooossee((BBrraannttaahhuuttcchhiinnssiiii)) SSuubbssppeecciieess STEVEN G. MLODINOW • PUGET SOUND BIRD OBSERVATORY • 5501 17TH AVE NE, SEATTLE, WASHINGTON 98105 • ([email protected]) PAUL F. SPRINGER • UNITED STATES FISH ANDWILDLIFE SERVICE, COOPERATIVE RESEARCH UNIT, HUMBOLDT STATE UNIVERSITY • ARCATA, CALIFORNIA (DECEASED 2 MAY 2007) BRUCE DEUEL • 18730 LIVE OAK ROAD, RED BLUFF, CALIFORNIA 96080 • ([email protected]) LAWRENCE S. SEMO • 9054 DOVER STREET, WESTMINSTER, COLORADO 80021 • ([email protected]) TONY LEUKERING • P.O. BOX 660, BRIGHTON, COLORADO 80601 • ([email protected]) T. DOUG SCHONEWALD • 1535 S. SKYLINE DRIVE, MOSES LAKE, WASHINGTON 98837 • ([email protected]) WILLIAM TWEIT • P.O. BOX 1271, OLYMPIA, WASHINGTON 98507 • ([email protected]) JESSIE H. BARRY • BURKE MUSEUM, BOX 353010, UNIVERSITY OF WASHINGTON, SEATTLE, WASHINGTON 98195 • ([email protected]) Abstract In this paper, we review what is currently known about the status and distribution of Cackling Goose, Branta hutchinsii, and its subspecies: B. h. hutchinsii, taverneri, minima, and leucopareia. We also discuss field identifi- cation of Cackling Goose subspecies, incor- porating information from our own recent field studies, and because Lesser Canada Goose (B. canadensis parvipes) closely resem- bles B. h. hutchinsii and taverneri, its range and identification are also reviewed. Taxonomy The taxonomy of Canada Goose (Branta canadensis) and Cackling Goose (B. hutchin- sii), which are here collectively referred to as “white-cheeked geese,” has a long and inter- esting history. Some authorities have lumped all populations into a single species, Canada Goose (sensu lato) (A.O.U. 1910, Swarth 1913, A.O.U. 1931), but most have recognized two to four species (Brooks 1926, Taverner 1931, Sutton 1932, Aldrich 1946, Hellmayr and Conover 1948). Aldrich (1946) asserted that there was near-unanimous agreement among Arctic biologists that “Canada Goose” consisted of two species, whereas Delacour Figure 1. The tiny triangular bill and rounded head of this minima Cackling Goose (called Ridgway’s Goose in this paper) is typical for (1951, 1954) recognized only one species this subspecies. Individuals of other subspecies would rarely, if ever, show the head and bill shape seen here. Also, the typical adult with twelve subspecies. Delacour’s taxonomy minima wing covert pattern is somewhat visible, with a gray base, dark subterminal band, and white terminal band. Note the promi- has generally been followed (e.g., Johnsgard nent neck collar subtended by black, reminiscent of the pattern typical of leucopareia Cackling Geese but present in some minima. Photographed at Ridgefield National Wildlife Refuge, Washington on 26 November 2005. Photograph by Steven G. Mlodinow. 1975, Bellrose 1980, Madge and Burn 1988, del Hoyo 1992, Mowbray et al. 2002), though According to current taxonomy, Canada Van Wagner and Baker 1990, Baker 1998, some authorities recognized fewer subspecies Goose consists mainly of large-bodied popula- Scribner et al. 2003). Furthermore, restriction (A.O.U. 1957, Palmer 1976). In 2004, the tions that breed away from tundra habitats, fragment length polymorphism analysis of American Ornithologists’ Union split Canada whereas Cackling Goose consists of smaller- mtDNA by Shields and Wilson (1987a, Goose (B. canadensis) into two species, bodied, tundra-breeding populations (cf. Han- 1987b) found a difference of 2% between the Canada Goose (B. canadensis) and Cackling son 2006-2007). two taxonomic groups, placing the divergence Goose (B. hutchinsii), based largely on mtDNA Studies of mitochondrial DNA (mtDNA) of Canada and Cackling Geese at approxi- evidence (Banks et al. 2004) and essentially support the split of Canada Goose (sensu lato) mately one million years ago. These genetic along the lines suggested by Aldrich (1946). into two species (Shields and Wilson 1987a, data also generally support Delacour’s (1951) 344 N O R T H A M E R I C A N B I R D S DISTRIBUTION AND IDENTIFICATION OF CACKLING GOOSE SUBSPECIES Geese), and are generally recognizable in the field. Furthermore, they have generally dis- crete breeding ranges, migratory paths, and wintering ranges. The high level of subspeciation among Cackling (and Canada) Geese may seem sus- pect when compared with other geese that breed in North America, such as Ross’s Goose (no subspecies), Snow Goose (two sub- species), Brant (at least two subspecies breed- ing in North America), or Greater White-fronted Goose (two or three sub- species). Unlike most other geese, however, Cackling and Canada Geese apparently form pair bonds during spring migration and on the breeding grounds rather than during win- Figure 2. The purple- to bronzy-glossed breast typical of minima Cackling Goose is obvious in this grouping. Note that the immature ter (Owen 1980), a process that would favor in the center has wing coverts that lack the bold pattern typical of adults (which is somewhat visible in the birds around it). Also note greater population structuring and that would how the head and apparent bill shape can vary with an individual bird’s posture. Photographed at Nisqually National Wildlife Refuge, cause greater genetic distinctiveness between Washington on 15 January 2006. Photograph by Steven G. Mlodinow. colonies/populations than in most other geese subspecific classifications (Shields and Wilson lations been subject to different selection pres- species (Ely and Scribner 1994), which in 1987a, Van Wagner and Baker 1990, Baker sures?” The answer is, “Almost certainly.” The turn could potentially lead to greater subspe- 1998, Shields and Cotter 1998), though these geographical isolation of Cackling Goose pop- ciation while also confounding our ability to distinctions were not detected by Scribner et ulations during the Wisconsin glacial maxi- discern the genetic differences among these al. (2003). The combination of geographical mum was first suggested by Ploeger (1968) subspecies. remoteness and uncertainties regarding iden- and has been generally accepted (Scribner et tification led to past assertions that B. c. al. 2003). During this time of isolation, the Distribution parvipes interbreeds with both taverneri and populations of Cackling Geese almost by defi- The breeding range of Cackling Goose extends hutchinsii (e.g., MacInnes 1962, 1966, Johns- nition occupied different habitats and were across tundra habitats from Baffin Island and gard 1975, Palmer 1976) and hence the subject to different selection pressures (Price northwestern Québec (and apparently rarely “lumping” of parvipes with taverneri by some 2008). Even now, leucopareia and minima use Greenland) west through the northern and earlier authorities (e.g., A.O.U. 1957, Palmer distinctly different breeding habitats from tav- western shores of Hudson Bay, across the 1976). However, direct evidence for hy- erneri and hutchinsii, which bridization between B. c. parvipes and any suggests a difference in nat- subspecies of Cackling Goose is lacking, and if ural selection pressures. such hybridization does occur, it is probably Since leucopareia is al- rather rare (J. Pearce, J. Leafloor, pers. lopatric, there is no cline be- comm.). This conclusion is supported by the tween it and other Cackling broad array of DNA studies cited above. Goose taxa. However, no ob- The validity of Cackling Goose subspecific vious phenotypic cline oc- designations has sometimes been questioned, curs between the parapatric as some studies fail to show a mtDNA differ- minima and taverneri (C. Ely, ence among the currently named subspecies pers. comm., B. Jarvis, pers. (e.g., Scribner et al. 2003). However, one comm.), which would sug- would expect a more rapid change in genes gest some level of ongoing subject to natural selection than in the neutral pre-mating or post-mating mtDNA genes used by most recent studies isolation (Price 2008). The evaluating taxonomic differentiation (Winker remaining subspecies, tav- et al. 2007). Consequently, phenotypic differ- erneri and hutchinsii, share ences between populations are likely to ap- similar breeding habitats, pear before such divergence is detectable by and their distribution along research using neutral mtDNA (Winker et al. the coast of the Beaufort Sea Figure 3. This leucopareia Cackling Goose (called Aleutian Goose in this paper) shows 2007). Additionally, Baker (2007) argues that is poorly known; it is not many of the features typical of its subspecies: a broad white neck collar that is not quite multiple markers are sometimes needed to known whether a cline be- complete and is narrowly subtended by black (though a bit less so than average); medium distinguish even between well-differentiated tween these two subspecies dark breast with a hint of gloss; dark gular stripe; and a short, steep forehead. This bird’s subspecies. exists. It has been the au- crown is a bit flatter than usual for leucopareia. Photographed at Humboldt National To pose the question as to whether Cack- thors’ experience that Cack- Wildlife Refuge, California on 24 January 2006. Photograph by Ron LeValley. ling Goose populations comprise separate ling Goose subspecies (as currently defined) mainland coastal slope of western Canada and subspecies, despite having indistinguishable tend to flock separately, even when sharing Canadian Arctic islands to Alaska’s North mtDNA (as currently evaluated), one must the same wintering grounds with other sub- Slope, and then southward to Alaska’s ask: “Are,