Population Status of Seabirds on St. Matthew and Hall Islands, 1985 and 1986

摘要

Numbers, reproductive success and food habits of cliff-nesting seabirds were studied on St. Matthew and Hall Islands in 1985 and 1986. Murre numbers varied markedly within years; during the daylight hours the variability was unrelated to time of day or weather conditions except that numbers were reduced when wind speeds exceeded about 7m/sec. Significant between-year differences in numbers of murres on the cliffs were documented. Kittiwake numbers were progressively higher in 1985 and 1986 compared to 1983 and numbers of kittiwake nexts were highest in 1986. Breeding chronology was most advanced and clutch sizes of kittiwakes were largest in 1986 but chick survival was poor. Walleye Pollock has been a major prey, particularly for murres. Annual variations in baseline numbers are probably related primarily to annual differences in foraging conditions and reproductive performance.