50 



Birds — Our Livini^ Resources 



BLKI (897 birds) 



St. George Is. 



RLKI (3,926 birds) ^ 



St. Paul Is. 



RLKI (115 birds) 



100- 

 75- 

 50- 

 25- 

 0- 



100- 

 75- 

 50- 

 25- 

 0- 



Semldi Is. 

 "blki ~ 



^(480 birds!" 



vs 



C. Thompson 



BLKI (4,088 birds) 



C. Peirce 



BLKI 



(1,295 birds) 



ZT^ 



Buldir Is. 



56 60 



72 75 78 81 84 87 90 

 Year 



Fig. 1. Population trends of hiack-legged kitliwakes (BLKI) and red-legged kittiwakes (RLKI) at 

 selected colonies in Alaska. The maximum count of birds or nests is indicated for each location. 

 Dashed lines indicate significant regressions {P < 0.051 of data collected since 1970 iP is a mea- 

 sure of the confidence that the decline or increase is statistically reliable. P < 0.05 indicates a 

 high probability that the population trend depicted actually occurred). See Hatch et al. 1993a and 

 references cited therein for data sources. 



trend in the production of offspring (Fig. 2); 

 some large colonies fail chronically. On 

 Middleton Island, for example, breeding has 

 been a total or near-total failure in 10 of the last 

 12 years (1983-94; Hatch et al. 1993a; Hatch, 

 unpublished data). The colony is declining at an 

 average rate of T7c per year (equal to adult mor- 

 tality), suggesting there is no recruitment (Hatch 

 et al. 1993b). If survival estimates obtained on 

 Middleton apply generally, the near-term future 

 of kittiwakes is unfavorable because average 

 productivity of 0.2 chicks per pair (Fig. 2) is 

 inadequate to maintain populations. 



Where red-legged kittiwakes (/?. brevi- 

 rosiris) have been monitored, they show popu- 

 lation trends similar to black-legged kittiwakes 

 (Fig. 1). In 1989 their population was down by 

 50% in the Pribilof Islands, but they were inore 

 numerous at Buldir Island than in the 

 mid-1970"s (Byrd and Williams 1993). Because 

 most of the world population of red-legged kit- 

 tiwakes breeds in the Pribilofs (75% on St. 

 George Island), their decline at that location is 

 cause for concern. 



Fig. 2. Productivity (chicks 

 fledged per nest built) of black- 

 legged kittiwakes in Alaskan 

 colonies. 1976-89. The number of 

 colony-years included in each 

 mean is indicated. See Hatch et al. 

 1993a for raw data. 



Murres 



Murres are large-bodied, abundant, and 

 wide-ranging seabirds that feed mostly on 

 schools of fish they pursue by diving underwa- 

 ter, sometimes to depths of 100-200 m (330-650 

 ft). Repeated counts of one or both murre 

 species (common murre, Uria acilge, and 

 thick-billed murre, U. lomvia) are available for 

 1 2 locations in Alaska (Fig. 3). Since 1970 com- 

 mon munes have declined significantly at two 

 colonies, and thick-billed munes have declined 

 at one. Murres (species not distinguished) 

 increased at two colonies over the same period. 

 Between the I950"s and the I970's, murres 

 increased at one location (Middleton Island) 

 and declined at another (Cape Thompson), but 

 they have since been relatively stable at both 

 colonies. In 1989 the Ex.xon Valdez oil spill 

 killed substantial numbers of common murres 

 at several colonies in the Gulf of Alaska (Piatt et 

 al. 1990a). 



Available data are insufficient to identify 

 overall trends. Murres are relatively consistent 

 producers of young, averaging 0.5-0.6 chicks per 

 pair annually in both species (Byrd et al. 1993). 



Threatened and Endangered Species 



No breeding seabirds are currently listed as 

 threatened or endangered in Alaska. The 

 short-tailed albatross (Diomedea albatnis), with 

 fewer than 1 ,000 individuals surviving, breeds 

 in Japan but visits Alaskan waters during most 

 months of the year. The species is vulnerable to 

 incidental take by commercial fishing gear, 

 especially gill nets and longlines (Sherburne 

 1993). 



Three species that breed in Alaska were 

 recently listed as category 2 (possibly qualify- 

 ing for threatened or endangered status, but 

 more information is needed for determination): 

 the red-legged kittiwake, marbled muirelet 

 {Brachyramphus mannorutiis). and Kittlitz's 

 murrelet (B. hrevimsths). As noted previously, 

 red-legged kittiwakes have declined substantial- 

 ly on the Pribilof Islands (Fig. 1 ). Marine bird 

 surveys conducted in Prince William Sound in 

 1972-73 and 1989-93 suggest a significant 

 decline of marbled murrelets in that area 

 (Klosiewski and Laing 1994). This finding is 

 corroborated by Audubon Christmas Bird 

 Counts from coastal sites in Alaska, which 

 reveal a downward trend since 1972 (Piatt, 

 unpublished data). Kittlitz's murrelet also 

 showed a decline in the Prince William Sound 

 surveys (Klosiewski and Laing 1994). With an 

 estimated population of fewer than 20.000 birds 

 range-wide (van Vliet 1993). this species is one 

 of the rarest of auks (Family Alcidae). Both 

 murrelets were adversely affected by the Exxon 

 Valdez oil spill (Piatt et al. 1990a). 



