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Ross's Goose
Chen rossii
Order
ANSERIFORMES
– Family
ANATIDAE
Authors: Ryder, John P., and Ray T. Alisauskas
Revisors: Jónsson, Jón E.

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Introduction

Ross's Goose head detail, Petaluma, CA, 8 March.
Figure 1. Distribution of Ross’s Goose in North America.

Ross’s Goose is the smallest of three light-colored (snow) geese that breed in North America. First reported as the “horned wavey” by the explorer Samuel Hearne (1795) during his travels in the interior of the central Canadian Arctic between 1770 and 1771, the species was not described for science until almost a century later (Cassin 1861). Ross’s Geese and Snow Geese often are collectively termed “light geese".

The arctic nesting grounds of Ross’s Geese remained unknown for another 80 years until Angus Gavin, a manager with the Hudson’s Bay Company, located them in the Perry River region of the central Canadian Arctic in 1940. These were the last of the light goose breeding areas to be discovered in North America (Cartwright 1940, Gavin 1940). Additional nesting colonies were found in the central Arctic by Hanson et al. (1956), Ryder (1969a), Alisauskas and Boyd (1994), and Kerbes (1994).

Historically, about 95 percent of all Ross’s Geese nest in the Queen Maud Gulf Migratory Bird Sanctuary in the central Canadian Arctic (Kerbes 1994, Alisauskas et al. 2012a). The species also nests along the west and south coasts of Hudson Bay, on Southampton and Baffin islands, and in the western Arctic. The main wintering area for the species is presently the Central Valley of California, though increasing numbers winter in Arkansas, Louisiana, New Mexico, Texas, and the north-central highlands of Mexico. This goose seldom associates with the large Greater Snow Goose (Chen caerulescens atlantica), which breeds farther north on high arctic islands and winters farther north and east (Atlantic Coast) than does Ross’s Goose, but it is often found in the company of the intermediate-sized Lesser Snow Goose (C. c. caerulescens), which breeds and winters at similar latitudes. And during the winter and early spring migration in California, Ross’s Goose often is found with the Cackling Goose (Branta canadensis minima).

Partly as a result of their close association, populations of Ross’s Geese have increased concurrently with those of Lesser Snow Geese; both populations have benefited from changed agricultural practices and lowered hunting pressures. At longer ranges, the two species can not always be distinguished from each other, particularly in studies from the air; thus some survey methods are constrained to consider both species simultaneously. At close range, the two species are readily distinguishable and have been used in comparative studies, in particular with respect to the effects of body size on physiological variables, endogenous reserves, nest site characteristics, time budgets and social behavior.

Ross’s Geese nest in colonies, usually interspersed with Lesser Snow Geese. Nests are on the ground, usually on sparsely vegetated islands and surrounding mainland areas of shallow arctic lakes, less frequently on riverine and offshore islands. This is a grazing species that feeds on grasses, sedges, and small grains.

Before 1900 and in the early 1900s, this goose was considered a rare species, possibly a consequence of open market hunting in California—it was commonly seen in the markets of San Francisco, Sacramento, Stockton, and Los Angeles (Grinnel et al. 1918). In 1931, when its numbers were estimated at 5,000 to 6,000 individuals, legislation was passed to prohibit hunting. Subsequent accidental and illegal killing, however, was thought to be a continued serious threat. Cahalane et al. (1941), in their 1940 report to the American Ornithologists’ Union Committee on Bird Protection, recommended (unsuccessfully) closing the Sacramento Valley in California to all light goose hunting, to protect the Ross’s Goose. In the 1960s and 1970s, Alberta and Saskatchewan delayed their light goose hunting season in an effort to reduce hunting mortality of this species.

As a result of these conservation measures, and even more because of significantly increased food availability, we have seen a remarkable expansion in the numbers of this species over the past few decades. The total number of birds has increased from a recorded low of 2,000–3,000 in the early 1950s to more than 188,000 nesting in the Queen Maud Gulf Migratory Bird Sanctuary in 1988 (Kerbes 1994). The population further increased to 519,282 in 1998 (495,086 in Queen Maud Gulf Migratory Bird Sanctuary and 24,196 elsewhere) and to 1,326,345 in 2006 (1,280,883 in Queen Maud Gulf Migratory Bird Sanctuary and 45,462 elsewhere) (Alisauskas et al. 2012b). The total continental population is believed to exceed 2 million birds at present (Alisauskas et al. 2009). Without drastic population control measures, continued increases in population sizes of the mid-continent Lesser Snow Geese and Ross’s Geese can be expected, with increased subsequent destruction of arctic wetland habitats.

This is a well-studied species. Its breeding biology is known from studies at: 1) Arlone Lake (67°22' N, 102°10' W; Hanson et al. 1956, Ryder 1967); 2) Karrak Lake (67°15' N, 100°15' W; Ryder 1972, McLandress 1983a, Slattery 1994, Slattery and Alisauskas 1995, Gloutney et al. 1999; 2001, Jónsson et al. 2006a,b; 2007, Traylor 2010, Traylor et al. 2012). Post-breeding biology at Karrak Lake was studied by Slattery and Alisauskas (2007); and 3) McConnell River (Caswell 2009). Studies of migration include those by Dzubin (1965) and Melinchuk and Ryder (1980) and on the wintering areas by McLandress (1979). Since 1955, numbers and locations of wintering Ross’s Geese have been estimated by the U.S. Fish and Wildlife Service during annual winter inventories of waterfowl.

Based on morphology, behavior, and genetic analyses, this goose is closely related to other anserine geese, particularly Lesser Snow Goose. Locations of spirit and skeletal collections are, respectively, in Wood et al. 1982 and Wood and Schnell 1986.