John L. Wells | Geology Reports

USGS1991

The distribution of seabirds and fish in relation to ocean currents in the southeastern Chukchi Sea

In late August 1988, we studied the distribution of seabirds in the southeastern Chukchi Sea, particularly in waters near a major seabird colony at Cape Thompson. Foraging areas were characterized using hydrographic data obtained from hydroacoustic surveys for fish. Murres ( Uria spp. ) and Black-legged Kitttiwakes Rissa tridactyla breeding at Cape Thompson fed mostly on Arctic cod, which are known from previous studies to be the most abundant pelagic fish in the region. Our hydroacoustic surveys revealed that pelagic fish were distributed widely, but densities were estimated to be low (e.g., 0.1-10 g∙m -3 ) throughout the study area and a few schools were recorded. Large feeding flocks of murres and kittiwakes were observed over fish schools with densities estimated to exceed 15 g∙m -3 . Fish densities were higher in shallow Alaska Coastal Current waters than offshore in Bering Sea waters, and most piscivorous seabirds foraged in coastal waters. Poor kittiwake breeding success and a low frequency of fish in murre and kittiwake stomachs in late August suggested that fish densities were marginal for sustaining breeding seabirds at that time. Planktivorous Least Auklets Aethia pusilla and Parakeet Auklets Cyclorrhynchus psittacula foraged almost exclusively in Bering Sea waters. Short-tailed Shearwaters Puffinus tenuirostris and Tufted Puffins Fratercula cirrhata foraged in transitional waters at the front between Coastal and Bering Sea currents.

Alaska↗

USGS1988

Populations, productivity, and feeding habits of seabirds on St. Lawrence Island, Alaska: Final report

A field camp was established at Kongkok Bay near the southwest cape of St. Lawrence Island and occupied continuously from 24 May to 2 September 1987. Permanent study plots were selected for both cliff and crevice-nesting species, and regular observations were made throughout the breeding season to document attendance patterns, breeding phenology, and success. Periodic collections of adults offshore and of chick meals in the colonies were used to determine the food habits of study species. Additional plots for population monitoring of murres and kittiwakes were established in colonies near Savoonga on the north side of the island, and counts were made there between 23 July and 1 August. Shore based work was supplemented with offshore studies of seabird foraging distribution from the USFWS vessel TIGLAX between 18 August and 3 September 1987. Populations of all study species in the Kongkok Bay area increased since the last study of seabirds there (murres 20, kittiwakes 87, Least Auklets 8, Crested Auklets 442). Pelagic Cormorants, Common Murres, and Thick-billed Murres exhibited average, or above average, breeding success at Kongkok in 1987. Black-legged Kittiwakes exhibited near-total reproductive failure. Crested and Least Auklets had high levels of breeding success after the effects of observer disturbance were taken into account. Predation by microtine rodents and foxes was a significant source of chick mortality on auklets. Feeding concentrations were found primarily north of Gambell in the Anadyr Strait or western Chirikof Basin. Kittiwakes were dispersed widely over the study area. Diets of all species studied were normal and, with the exception of kittiwakes, there was no evidence of problems in obtaining food. Current methods for assessing population changes in cliff-nesting species are considered adequate, but better techniques are needed for crevice-nesting auklets. Time-lapse photography offers the greatest potential for monitoring auklet numbers. A protocol is suggested for monitoring populations of murres, kittiwakes, and auklets at colonies in the Bering and Chukchi Seas. It calls for annual visits to selected colonies during two stages of the nesting cycle to assess numbers and breeding productivity. The breeding failure of Black-legged Kittiwakes on St. Lawrence Island in 1987 was part of a pervasive syndrome of failure in this species observed throughout the Bering Sea and Gulf of Alaska in recent years. The causes of recurrent, widespread breeding failure need to be identified if kittiwakes are to have a role in area-wide population monitoring during the period of Alaskan development by the oil and gas industry.

Alaska↗