POPULATION STATUS AND TRENDS

In the following accounts, eastern Arctic refers to the area east of approximately longitude 95o W; the central Arctic refers to the area between 95o W and approximately 115o W, and the western Arctic refers to the area west of 115o W (Fig. 2.2a, 2.2b).

Lesser Snow Goose (LSGO)

LSGO populations in the mid-continent have been indexed annually during winter since mid- century. The mid-winter index (MWI) rose 300% from 0.8 million geese in 1969 to 2.7 million in

1994 (Mississippi and Central Flyway Councils, unpublished data) (Fig. 2.1). A complete photographic inventory of eastern Arctic nesting colonies by Kerbes (1975) suggested that winter indices averaged about half the actual spring number (e.g., when MWI was 0.8-1.0 million geese, he estimated 1.9 million at nesting colonies); Boyd et al. 1982) corroborated this underestimation and used a factor of 1.6 to adjust MWI. The probability of mid-winter index counts under-estimating the real population size has probably increased as the population has grown, due to the daunting task of monitoring the expanding wintering area used by geese, and the limitations of survey techniques for large clustered populations. The current actual population of mid-continent LSGO geese is probably between 4.5 and 6 million.

Recent breeding ground surveys in the eastern and central Arctic have confirmed substantial growth at several colonies and establishment of new colonies (Fig. 2.3a-d) (Reed et al. 1987, Alisauskas and Boyd 1994, Kerbes 1994 and unpublished data, Cooke et al. 1995, Hudson Bay Project, unpublished data). D. Caswell, personal communication, conducted surveys on southwestern Baffin Island that revealed 1.2-1.4 million breeding adults in 1994 and 1995. LSGO populations in central and western Arctic Canada apparently grew more gradually (than those of the eastern Arctic) before the 1980's but now (the last decade) appear to be on a similar track. Central and western Arctic nesting areas now each contain more than 500,000 breeding birds (cf. Alisauskas and Boyd 1994 in ROGO account below). The Egg River, Banks Island colony experienced extremely rapid growth from 1985 to 1995 (Dzubin 1979, Kerbes 1983, R. H. Kerbes, unpublished data). An Alaskan nesting population established in the late 1960s has grown gradually, partly through immigration (Johnson 1995).

Some exceptions.-- Unlike most LSGO populations, the total population returning in spring to Wrangel Island, Russia declined recently to 70,000 birds from 150,000 in 1970 (Pacific Flyway Management Plan, 1992) (Fig. 2.4a). Lesser snow geese that breed on Wrangel Island are composed of two different sub-populations that winter in separate locations, either in the Fraser-Skagit Delta system of British Columbia and Washington, or in California and Oregon (McKelvey et al. 1989, Syroechkovsky et al. 1994). An Asian population, thought to nest on the Arctic coast of the Russian Far East as far west as the Lena River and to winter in Japan, was eliminated due to human harvest (V.V. Baranyuk, pers. comm.).

The complex of nesting colonies on the West Hudson Bay coast, centered at McConnell River, grew exponentially from the 1940s to late 1970s to a high of 215,000 breeding pairs but has declined since 1985 to less than 75,000 breeding pairs (Kerbes 1982, MacInnes and Kerbes 1987, Kerbes et al. 1990, R. Kerbes, pers. comm.) (Fig. 2.4b). Habitat destruction by geese and emigration of adult geese to other nesting areas are implicated as causes of the decline.

Ross' Goose (ROGO)

ROGO are difficult to index because of mixing with LSGO in both winter and at nesting colonies. However, a technique using late winter surveys (when ROGO are somewhat isolated from LSGO) showed an increase in numbers from 8,000 in 1957 to over 38,000 in 1968 (Bellrose 1980). McLandress (1979) estimated a 7% per annum growth rate from 1964 to 1976, at which time the winter population index was 107,000 birds. Nesting birds in the Queen Maud Gulf region increased from about 2,000 in 1949 to 34,000 in 1965-67 to 188,000 in 1988 (Kerbes 1994) (Fig. 2.5a). Thus, almost 400,000 ROGO migrated from the breeding grounds in the early 1980s. Alisauskas and Boyd (1994) documented further growth of existing colonies and establishment of new ones. They suggested the nesting population at the 2 major colonies doubled between 1988 and 1990-91. They estimated a population of over 900,000 adult ROGO and LSGO combined in the Queen Maud Gulf area in 1990-91; ROGO make up about 42% (210,000) of the largest colony at Karrak Lake, which contained an estimated 500,000 total "white" geese in 1995 (R. Alisauskas, unpublished data).

A few nesting ROGO were present in most LSGO colonies in the eastern Arctic in the early 1970s (MacInnes and Cooch 1964, Prevett and MacInnes 1972, Prevett and Johnson 1977). Since that time, the population has exploded to an estimated 40,000 birds at the McConnell River colony, NWT in 1995 (R. Forsyth, Canadian Wildlife Service and R. Bromley, Government of Northwest Territories, unpublished data), and to 1,000 on western Baffin Island (D. Caswell, Canadian Wildlife Service, unpublished data). In addition, up to 14% of "white" geese within sections of the Boas River nesting area on Southampton Island, NWT are ROGO (T. Moser and K. Abraham, unpublished data). If most individuals from these eastern subpopulations migrate in fall to the mid-continent area, the overall number of ROGO there may exceed 100,000 birds. B. Sullivan (Texas Parks and Wildlife Department, unpublished report) provided an estimate in 1995 from Texas alone of 70,000 ROGO which supports this suggestion (see also Kerbes 1994).

Greater Snow Goose (GSGO)

The population with the best documented growth data among all white geese is the GSGO. A single population of this subspecies exists in eastern North America. It grew from a few thousand in the 1930s to 50,000 by the mid 1960s, to over 500,000 in fall migratory flights in the late 1980s (Gauvin and Reed 1987, Reed 1990). Spring migratory populations (measured by the use of complete photography on staging areas) reached 612,000 in 1995 (Reed 1996) (Fig. 2.5b). Following 7 decades of slow growth, the population increased seven-fold from 1965 to 1985 and it has nearly doubled between 1985 and 1995. Surveys of breeding numbers on the largest colony (Bylot Island) have been made every 5 years since 1983. They have showed an increase from 16,000 breeding adults in 1983, to 26,300 in 1988, to 55,000 in 1993 (Reed and Chagnon 1987, Reed et al. 1992, Reed, pers. comm.). In addition to the excellent long-term population monitoring, the geographic expansion of the breeding grounds, spring staging areas, wintering grounds, reproductive success and annual harvest have been recorded carefully (Reed 1976, Reed 1990, Gauthier et al. 1988, Bédard and Gauthier 1989). These data provide an excellent example of the information necessary to determine the causes of population increase of geese (Gauvin and Reed 1987, Reed 1992).

The rapid population growth phases of the mid-continent LSGO population, the ROGO and LSGO populations in Queen Maud Gulf, and the GSGO population all occurred at about the same time (Boyd, Cooch and Smith 1982, Kerbes 1994, Gauvin and Reed 1987). In the period between 1966/1967 and 1974/1975 all of these populations doubled. Since that time, LSGO have nearly doubled again, and GSGO and ROGO populations have achieved even higher growth rates.

Greater White-fronted Geese (GWFG)

Mid-continent Greater White-fronted Geese have, like other geese, increased dramatically over the past 40 years. In the Mississippi Flyway, only 12,000 were counted in the first coordinated aerial surveys of the mid-1950s (Yancey et al. 1958). They have increased over ten-fold to a 1996 MWI of 145,100 (K. Gamble, Mississippi Flyway Council, unpublished data); the increase has been similarly dramatic in the central flyway (D. Sharp, Central Flyway Council, unpublished data) (Fig. 2.6a-b). GWFG that winter in these flyways have been managed and monitored as two groups: Western and Eastern Mid- continent. However, Kraft and Funk (1991) cited evidence that this distinction might not be valid and recognized an urgent need for better information to delineate and monitor populations. Since then, coordinated September surveys in Saskatchewan and Alberta and the northern states of the Central and Mississippi Flyways have been conducted (from 1992 to 1995). These surveys tallied 625,847 geese in 1992, 677,489 in 1993, 727,726 in 1994 and over 1 million in 1995 (Canadian Wildlife Service, D. Neiman, unpublished data, Zenner 1996).

Krapu et al. (1995) studied the spring staging ecology of mid-continent GWFG, particularly the use of habitat, nutrient accumulation, and agricultural food contributions to energetics of pre-breeding birds. They believe that GWFG now "arrive on Arctic breeding grounds with larger and less variable fat reserves than before modern agricultural development". They attribute this to increased corn availability and use, beginning in the 1940s when corn harvesting techniques provided waste grain, but accelerating in the 1960s and 1970s when corn yields increased. They suggest that increased fat deposition in spring positively affects recruitment.

GWFG in portions of the Central Flyway where wetland loss is >90% (Krapu et al. 1995, Friend and Cross 1995) are vulnerable to disease epizootics, especially avian cholera. High concentrations on the relatively few remaining roosting wetlands allow for easy transfer of the disease. Population growth as exhibited in recent years likely exacerbates these problems.

Giant Canada Geese (Giant CAGO)

Populations of Giant Canada geese have grown from near extinction to nuisance levels over the past 40 years; from an estimated 55,000 birds in 1965, the various populations of temperate breeding birds now contain an estimated 2 million geese, with over 1 million in the Mississippi Flyway alone (Rusch et al. 1995, Rusch et al. 1996) (Fig. 2.7a). Much of this growth is directly attributable to planned management actions of agencies and private sponsors, including restoration and introduction programs, closed hunting seasons, and restricted harvest expressly intended to increase populations. Equally, however, this growth is an outcome of the species adaptability and colonization of unoccupied habitats under protection. This has occurred in an urban and rural landscape much altered since they were extirpated from many jurisdictions, which offered countless unintentional sanctuaries. The agricultural energy subsidy evident in the growth of white goose populations is similar in effect for Canada geese and is in part responsible for the growth of these goose populations. (Fig. 2.7b).

Mississippi Valley Population Canada Geese (MVP CAGO)

The Mississippi Valley Population of Canada geese is the largest population of the interior subspecies. Management through harvest regulations and habitat programs have had the objective of increasing its size to 300,000 in winter (USFWS 1979) and later to 900,000 in spring (Tacha 1991). Sustained increases have occurred over the past 40 years, from less than 40,000 birds in winter to a current MWI of over 900,000 (Rusch et al. 1995, Mississippi Flyway Council, unpublished data) (Fig. 2.8). A period of rapid growth from 1964 to 1975 was followed by an erratic pattern until 1983, during which time the annual count reached an unprecedented peak of 576,000, but the mean MWI did not change significantly. The counts were possibly confounded by undetected growth of giant populations at that time. Since 1983, the population has rapidly and steadily increased, resulting in a tripling of the MWI. However, debate about the accuracy of the MWI and the inclusion of giants led to initiation of comprehensive breeding ground surveys in 1989. These show a spring population of 700,000 to over 900,000 from 1989-1996 and a fall flight of 1 to 1.5 million varying annually depending on current and recent years' production (J. Leafloor, unpublished data).

One of the consequences of the sustained growth in numbers is the change in nesting density and occupation of new range. Before about 1975, few nesting or brood-rearing Canada geese occupied the near coast (10 km) zone of Hudson Bay or northwest James Bay (H. Lumsden, pers. comm.). Annual photographic surveys from 1958-1970 made during the brood-rearing period covered the coast from Moosonee, Ontario to Eskimo Point, Northwest Territories (Hanson et al. 1972). A special effort to photograph broods for early assessment of reproductive success became possible only in the early 1980s. In addition, banding of coastal breeders was difficult and limited until the early 1980s. This suggests, at the least, an increase in use of coastal brood rearing areas, possibly a result of increased population density. Numbers of breeding pairs have tended to decline over the 1991-1996 period (J. Leafloor, pers. comm.), which may be an early signal of the population nearing its carrying capacity. A complicating factor is the increase of nesting lesser snow geese in the coastal zone of the MVP range from 1970 to the present; two small colonies (<2500 pairs) have been established and the major colony at Cape Henrietta Maria has nearly quadrupled in number, and doubled in area of coastal range occupied (Hudson Bay Project, unpublished data).

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