Changes in Nesting Behavior of Arctic Geese

Changes in Nesting Behavior of Arctic Geese
		by *Edward T. LaRoe* *Donald H. Rusch* National Biological Service

Fig. 1. Location of four monitoring sites. Sites chosen represent localities with information for 5 or more years. Site 1McConnell River (60š 50'N, 94š 25'W; snow goose [Chen caerulescens] and small Canada goose [Branta canadensis]); 2 La Pérouse Bay (58š 24'N, 94š 24'W; snow goose); 3Cape Churchill (58š 25'N, 93šW; medium Canada goose); and 4South-hampton Island (63š 60'N, 86šW; snow goose).

As part of the joint United States-Canada efforts to monitor populations of Arctic geese and to provide data necessary to set hunting regulations, scientists have recorded not only goose population levels, but also nesting behavior. MacInnes et al. (1990) analyzed data from four long-term studies of five different Arctic goose populations. These studies documented the date the eggs hatched and the clutch size (number of eggs per nest) over 35 years (Fig. 1).

The dates of nest initiation and hatch are clearly affected by climate and are delayed by cold weather. The records not only show wide fluctuations from year to year in response to annual variations in climate, but also demonstrate a consistent trend toward earlier hatching over the period (Fig. 2). Young Arctic geese today, on the average, hatch about 30 days earlier than they did 35 years ago; during the same time, average clutch size has shrunk (Fig. 3). MacInnes et al. (1990) suggest the change in nest date is a result of climatic amelioration, that is, warming (although whether from a long-term trend or short-term cycle is unclear), and the change in clutch size is a result of habitat deterioration.

Fig. 2. Date of first egg. Although all sites displayed large fluctuations, both the date of first egg and the mean (average) hatch date became significantly earlier during the period 1951-86. There were no significant differences in the slopes of trends among sites or species.

Canada goose (Branta canadensis). Courtesy E.T. LaRoe

For further information:
Donald H. Rusch
National Biological Service
226 Russell Labs
1630 Linden Drive
Madison, WI 53706

References
MacInnes, C.D., E.H. Dunn, D.H. Rusch, F. Cooke, and F.G. Cooch. 1990. Advancement of goose nesting dates in the Hudson Bay Region, 1951-86. Canadian Field Naturalist 104:295-297.