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.
