Breeding and migration ecology of the tule white-fronted goose. The tule greater white-fronted goose is one of the few waterfowl in North America considered to be at risk by the International Waterfowl Research Bureau. Counts on their wintering grounds in the Central Valley of California indicate that the population currently consists of fewer than 8,000 individuals (Pacific Flyway Council 1991; D. Orthmeyer, pers. comm.). Tule geese have received little attention since work stimulated by the discovery of their breeding grounds on the west side of Cook Inlet in 1979 (Timm et al. 1982, Wege 1984, Ely and Dzubin 1994), even though less than half of the wintering population could be accounted for in this summering area (Timm and Sellers 1981). Recent surveys indicate a 90% decline in the number of tule geese using the west side of Cook Inlet since the early 1980s (Campbell 1992). The decline followed a major eruption of Redoubt Volcano that caused considerable alteration to landscapes used for nesting and brood rearing. Despite their small population size, tule geese are still harvested in appreciable numbers by sport hunters from Alaska to California. Tule geese are also vulnerable because they have a only a very limited distribution throughout their range. They are found in only a few areas of California and Oregon during autumn, winter, and spring and during summer nest only in the Cook Inlet Basin and stage in glacial valleys of southeast Alaska. Because of the concerns for this population we began a collaborative research project with the Western Ecological Science Center with the objectives of defining the distribution and habitat use of tule geese in Alaska and identifying factors potentially limiting the population. Our initial research lead to the discovery of new nesting and migration areas, and has revealed that the majority of tule geese nest in the Susitna Military operations area (MOA); as such they are subjected to (high elevation) military aerial exercises over most of their breeding range. Subsequent funding by the Department of Defense has helped us better understand the relationship between staging and breeding areas, and lead to the development of new technology for remotely monitoring avian heart rates and their responses to aircraft.