Ecology of the Long-Tailed Jaeger at Lake Hazen, Ellesmere Island

Abstract

Reports on the 1966 studies of breeding density, timing, chick growth and food habits of Stercorarius longicaudus near the northern margin of its extensive range (66 N on Hudson Bay to 83 N) where it is free of competition from the pomarine and parasitic jaegers. The great variation in breeding of the long-tailed jaeger is related to the lemming populations, which provide >90% of the jaeger's food; clutch size also appears to be adjusted to food supply. This small jaeger species adapts to the High Arctic with its efficient use of lemming highs which may not be very great and its use of insect prey, especially by the chicks. Fledging time is approx. three wk, one week less than the larger jaegers. Egg-laying dates vary widely between years and within populations. Juvenile birds, mainly snow buntings and shore birds make up most of the other vertebrate prey. A description of the Camp Hazen environment and a comparison of the long-tailed jaegers with north Alaska populations are included.