The status of seabirds at Chisik and Duck Islands during the summer of 1986

Nishimoto, Mike; Thounhurst, Kim; Early, Tom

Chisik and Duck islands are located in lower Cook Inlet about 193 km (120 mi) southwest of Anchorage, Alaska. They become part of the Alaska Maritime National Wildlife Refuge in 1980; the islands were initially given protective status in 1909 as the Tuxedni Reservation. Seabirs of Chisik/Duck islands were monitored on July 16-20, and August 5, 1986. Two breeding pairs of peagic cormorants (Phalacrocorax pelagicus) and sixteen pairs of double-crested cormorants (P. auritus) were found at this colony in 1986. About 26,650 black-legged kittiwakes (Rissa tridactyla) an 3,500 common murres (Uria aalge) were estimated during this survey. It was often difficult to make accurate population estimates due to the high cliffs of Chisik Island. Seven black-legged kittiwake monitoring plots were established on Chisik/Duck island.s Kittiwak productivity ranged from 0.01 to 0.50 chicks/nest. Plots that essentially failed were all located near the southern tip of Chisik Island. They produced 0.08 chicks/nest or less. Plots on east Chisik and Duck Island had 0.30 to 0.50 chicks/nest. This colony is known for its poor productivity. In six previous years of monitoring, there were only two years with any measurable kittiwak production. Reproductive failures were attributed to weather, availability of food and predation by glaucous-winged gulls (Larus glaucescens). The gull population may have expanded artifically by a diet supplemented with cannery by-products. Seabirds were also entangled by setnets. Eight dead murres were seen near a setnet site in 1986. In previous years, setnets have been a source of mortalities among common murres, puffins (Fratercula spp.), cormorants, pigeon guillemots (Cepphus columba), and common eiders (Somateria mollissima).