Our Living Resources — Birds 



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Other Species 



Scant int'orniation is available to assess 

 numerical changes for most seabird species in 

 Alaska. We know that some species were seri- 

 ously reduced or locally extirpated by foxes 

 introduced to islands in the 1800"s and early 

 i900"s. About 450 islands from southeastern 

 Alaska to the western Aleutians were used as 

 release sites for arctic (Alopex lagopus) and red 

 foxes {Viilpes viilpes) (Bailey 1993). The species 

 most affected included open-ground nesters such 

 as gulls (Lanis spp.). tems {Stenui spp.l. and ful- 

 mars {Fuliiuiriis iiUicialis). and bumming birds 

 like ancient murrelets {Synrhlihdraniphits untiqii- 

 iis). Cassin's auklets {Ptychonunphus alfiiticus). 

 tufted puffins {Fnitercula cirrhata), and 

 stomi-petrels iOceanodroma spp.). In spite of 

 natural die-offs and eradication efforts, foxes 

 remain on about 50 islands to which they were 

 introduced (Bailey 1993). 



Recent counts suggest that fulmars are 

 increasing at two of their major colonies 

 (Semidi Islands and Pribilof Islands), and sever- 

 al small colonies have been established since 

 the mid-1970"s (Hatch 1993b). Counts of least 

 and crested auklets {Aeihia piisilla and A. 

 cristateUa) also indicate possible increases at 

 two colonies in the Bering Sea (Piatt et al. 

 1990b: Springer etal. 19931 



Red-faced cormorants (Pluilacroconix urilc) 

 declined about 50% on the Semidi Islands 

 between 1978 and 1993. while pelagic cor- 

 morants (P. pelagiciis) increased on Middleton 

 Island between 1956 and the mid-1970"s 

 (Hatch, unpublished data). Glaucous-winged 

 gulls ^Llll■lls gluucescens) increased on 

 Middleton from none breeding in 1956 to more 

 than 20,000 birds in 1993 (Hatch, unpublished 

 data); this species has also shown marked 

 increases following removal of introduced foxes 

 at several sites in the Aleutian Islands (Byrd et 

 al. 1994). Marine bird surveys in Prince 

 William Sound (Klosiewski and Laing 1994) 

 suggest that arctic tems {Sterna panuiisaea). 

 glaucous-winged gulls, pelagic cormorants, 

 homed puffins (Fnitercula cornicidata), and 

 pigeon guillemots [Cepphus columba) have all 

 declined in that area. Tems and guillemots have 

 recently increased on several Aleutian Islands 

 following fox removal (Byrd et al. 1994). 



Factors Affecting Seabirds 



Alaskan seabirds are killed incidentally in 

 drift gill nets used in high seas (DeGange et al. 

 1993), and oil pollution poses a significant 

 threat, as demonstrated by the Exxon Valdez. 

 spill. There is little doubt, however, that the 

 introduction of exotic animals, especially foxes. 

 but also rats, voles, ground squirrels, and rabbits 



TBMU (1,335 birds) 



St. Matthew Is. 



COMU (1,528 birds) 



St, Lawrence Is. 



(1.123 murres) 



100 

 75 

 50 

 25 

 



100 

 75 

 50 

 25 

 



100 

 75 

 50 

 25 

 



100 

 75 

 50 

 25 

 



Semidi Is- 



(3,117 murres) 



^\^ 



Bluff 



(2,541 COIulU) 



C Peirce 



(2,749 COMU) 



xz 



C. Thompson 



St, George Is, 



(1,842 birds) 



TBMU 



C , Lisbu rne 

 (23,428 murres) 



(19,613 birds) 



SI, Paul Is 



Buldir Is, 



(2,035 murres) 



COMU (2,933 birds) 



56 60 70 73 76 79 82 85 



56 60 70 73 76 79 82 85 88 91 



Year 



has been the most damaging source of direct 

 mortality associated with human activity 

 (Bailey 1993). Unlike one-time catastrophes, 

 introduced predators exert a continuous nega- 

 tive effect on seabird populations. 



Changes in food supply, whether natural or 

 related to human activity, are another important 

 influence on seabird populations. The postwar 

 period from 1950 to the 1990"s has seen explo- 

 sive growth and constant change in commercial 

 fisheries of the northeastem Pacific (Alverson 

 1992). Driving these changes, or in some cases 

 possibly driven by them, are major shifts in the 

 composition of marine fish stocks. In the Gulf 

 of Alaska, for example, a shift occurred in the 

 late 1970's and early 1980's toward greater 

 abundance of groundfish (cod. Gadiis macro- 

 cephaliis: various flatfishes; and especially 

 walleye pollock, Theragra chalcogramma), 

 possibly at the expense of small forage species 

 such as herring (Clupea harengus). sandlance 

 (Ammodytes hexaplerus). and capelin {Mallotiis 

 vHlosiis: Alverson 1992) (Fig. 4). Coincident 

 with these changes, diets of a variety of seabirds 

 such as murres. murrelets, and kittiwakes have 

 shifted from being predominantly capelin-based 



COMU 

 TBMU 



murres 

 regressions 



Fig. i. Population trends of com- 

 mon muires (COMU) and 

 tliicl<-billed muires (TBMU) at 

 selected colonies in Alaska. 

 Counts of "murres" included 

 unspecified numbers of common 

 and thick-billed murres. The max- 

 imum count of individuals is indi- 

 cated for each location. Dashed 

 lines indicate significant regres- 

 sions (P < 0.05) of data collected 

 since 1970. See Hatch 1993a for 

 data sources. 



