Impacts of Water Levels on Breeding Canada Geese and the Methodology for Mitigation and Enhancement in the Flathead Drainage. Annual Report 1985

摘要

The lower Flathead System Canada Goose Study was initiated to determine population trends and the effects of water level fluctuations on nest and brood habitat on the southern half of Flathead Lake and the lower Flathead River as a result of the operations of Kerr Dam. This report presents data collected during the 1985 field season. Goose use patterns were similar to those observed in 1984. From late summer through fall use of the river was low and use of the reservoirs was high. Use of the river increased as reservoirs began to freeze and by mid-December most geese were using the river. The lower half of the river froze in late January and most geese apparently left the valley. Use of the river increased during the nesting period and remained relatively stable through the brooding period. The indicated pairs/nest ratio was 1.2 for the entire river and 1.5 for the southern half of the river. Fifty percent (26 of 52) of the tree nest structures on the river were used by geese in 1985. Overall nesting success of geese using nest structures was 84%. Seventy-one nests were located on the river in 1985. The total number of nests found on the nesting islands of Flathead Lake was 166 during 1985. A riparian community type classification is currently being developed and will be used next year to map the study area. Nest and random sites as well as general island characteristics were investigated and comparisons were made between areas used and areas available to nesting geese. Activity budget analyses indicated that the two primary activities of goslings were feeding and resting while alert and feeding were the two primary activities of adults. Herbaceous habitats were used by broods more than any other type and were important for all activities. (ERA citation 11:027097)