192 



D. E. MC KNIGHT AND C. E. KNODER 



sands of seabirds pouring off a rookery is 

 truly spectacular, but each such occurrence 

 during incubation and brooding periods 

 causes a rain of eggs or young to fall from the 

 cliffs (Sowl and Bartonek 1974). Temporarily 

 abandoned chicks and eggs are susceptible to 

 predation by gulls or jaegers. 



Even for species nesting on level ground, 

 aircraft overflights close to breeding colonies 

 may cause major losses to young and eggs. 

 Sladen and LeResche (1970) reported that 

 flights by an LH-34 helicopter (at 305 m alti- 

 tude) over an Adelie penguin (Pygoscelis ade- 

 liae) colony caused some egg loss. Landing 

 this aircraft 183 m from the colony caused 50 

 to 80% of the birds to flee territories, result- 

 ing in egg and chick loss. Disturbance caused 

 by visitors walking through or near nesting 

 areas of the South African gannet (Sula 

 capensis) on Bird Island, Lamberts Bay, 

 South Africa, caused desertion of nesting 

 sites (Jarvis and Cram 1971). Studies of dis- 

 turbance on breeding black brant, Pacific 

 eiders, glaucous gulls (Larus hyperboreus), 

 and arctic terns at Nunaluk Spit and Phillips 

 Bay, Yukon, in July 1972 indicated that hu- 

 man presence was the most critical form of 

 disturbance affecting incubating behavior of 

 these species (LGL Limited 1972a). Dis- 

 turbance by aircraft especially helicopters- 

 affected the normal incubating behavior of all 

 species except Pacific eiders. Nesting success 

 of black brant and arctic terns was reduced by 

 this disturbance. 



Disturbance can adversely affect molting 

 birds. The process of molting places heavy 

 energy demands on birds, and particularly on 

 waterfowl whose molt results in a flightless 

 period; few areas provide adequate protection 

 from predators necessary during this period. 

 Prime molting areas are scarce along the arc- 

 tic coast, yet are vital to the welfare of thou- 

 sands of sea ducks and seabirds. Studies con- 

 ducted by LGL Limited (19726) indicated that 

 aircraft traffic over sea duck molting areas 

 altered normal behavior, and therefore had a 

 detrimental effect. Recommendations result- 

 ing from these studies were that air traffic be 

 suspended over these areas during the molt- 

 ing season. 



For some arctic-nesting waterfowl, premi- 

 gration staging activity, during which fat re- 

 serves to sustain southward migration are 



stored, is a very important component of the 

 annual cycle (Delacour 1964). Snow geese, 

 breeding mainly in arctic Canada, concentrate 

 in large numbers on staging grounds along 

 the Beaufort Sea coast of eastern Alaska and 

 the Yukon. Because gas compressor stations 

 would be required along the proposed arctic 

 gas pipeline route, experimental studies were 

 conducted in September 1972 to determine 

 the effect of disturbance from sounds gener- 

 ated by compressors (LGL Limited 1972c). 

 These studies indicated that compressor noise 

 was disruptive to staging geese. 



Indirect effects on marine bird resources re- 

 sulting from development activities may ulti- 

 mately prove to be more detrimental than the 

 aforementioned direct factors. It is conceiv- 

 able that the impact of these industries, 

 mainly on the benthic and demersal fauna of 

 the coastal areas, could greatly lower the 

 carrying capacity of this habitat for marine 

 birds (Bartonek et al. 1974). Because of the 

 simplified and short arctic food chains and the 

 lack of alternative food sources in these areas, 

 arctic ecosystems would be particularly vul- 

 nerable to this type of problem (Burns and 

 Morrow 1973). 



Ecological or toxic influences on several 

 food species could result in substantial de- 

 clines in bird populations. In the Arctic, 

 where temperatures are low, and bacterial and 

 other decompositional activities are conse- 

 quently slow, spilled oil would persist for 

 many years, with concomitant deleterious ef- 

 fects on the marine organisms of the area 

 (Burns and Morrow 1973). Reduced recruit- 

 ment of young would no longer balance inevi- 

 table or density-independent population mor- 

 tality (Ashmole 1971). Although indications 

 are that arctic species are the most vulnerable 

 to this type of impact, the lack of knowledge 

 of the feeding niches of most seabirds discour- 

 ages further evaluation of this potential prob- 

 lem. It is obvious, however, that ecology of 

 arctic birds is least understood, and these 

 species are the most vulnerable to the detri- 

 mental effects of man-caused environmental 

 degradation. 



Conclusions 



Predictability of the impact of resource de- 

 velopment on marine birds in northern waters 



