In spite of these adaptations, arctic bird species tread a thin line between extinction and survival, and natural disasters take a heavy toll. Bailey and Davenport (1972) reported a massive mortality in a pelagic population of common murres in Bristol Bay, Alaska, during April 1970. They felt that this disaster, resulting in the death of probably 100,000 or more birds, most likely resulted from starvation precipitated by severe weather. Barry (1968) reported a similar loss to starvation of about 100,000 eiders along the Beaufort Sea coast during the extremely cold spring of 1964. Observers along Alaska's Beaufort Sea reported finding eiders and oldsquaws dead and dying from the effects of cold weather in 1970 (Bartonek et al. 1971). It is readily apparent that the tenuous existence into which these birds have evolved leaves them particularly vulnerable to the man-induced stress of developments during the arctic summer.
Direct Effects of Oil Pollution
The most obvious, and perhaps the most disastrous consequence of petrochemical development on northern marine bird populations is that of a major oil spill or a well blowout into marine waters. Although temperate and tropical waters are apparently able to assimilate oil spills and chronic pollution from petroleum and its products (Nelson-Smith 1972), this has not been demonstrated to be true for arctic waters. In fact, studies in the Beaufort Sea have shown that the bacteria that degrade oil do not use hydrocarbons at the ambient temperatures of the Arctic (Glaeser and Vance 1971). Therefore, a large oil spill in the Arctic could persist for many years. As demonstrated by Campbell and Martin (1973), the diffusion and transport mechanisms generated by the pack-ice dynamics of the Beaufort Sea and the slow rate of oil biodegradation under arctic conditions would combine to diffuse an oil spill over the sea and eventually deposit oil on the ice surface. This, in turn, would lower the natural albedo over a large area and melt the ice in the area of the spill. This pack ice supports an under-ice community which is an important food source for phalaropes, jaegers, gulls, terns, and other seabirds (Watson and Divoky 1972).
As indicated by Nelson-Smith (1972) many investigators have stated that a spot of oil "no bigger than a dollar" on the breast of a bird is enough to bring about death by exposure, at least in the colder seas. It is easy to see the relative vulnerability of already stressed birds in arctic areas to a spill, and because of the concentration of these birds in available open-water areas, possibilities for catastrophic mortalities are evident.
Such disasters already have occurred in north Pacific waters. Dickason (1970) reported an incident in which diesel oil reaching the Alaska coast, probably from the sinking of two Japanese freighters some distance offshore, affected an estimated 90,000 murres. J. G. King, Jr. (cited in Bartonek et al. 1971) estimated that at least 100,000 birds, mostly alcids and waterfowl, died in the vicinity of Kodiak Island during winter 1970 as a result of oil pollution (probably ballast dumped by tankers entering Cook Inlet). It must not be forgotten that chronic pollution in similar areas where oil development and transport activities are taking place probably kills more birds every year than die after a single catastrophic spill. Total annual losses due to oil in the North Sea and North Atlantic, excluding disasters, amount to 150,000 to 450,000 seabirds (Nelson-Smith 1972).
That oil pollution, both chronic and catastrophic, can dramatically affect populations of marine birds has already been demonstrated elsewhere. Uspenskii (1964) reported that more than 30,000 wintering oldsquaws perished from oil pollution near Botland Island in the Baltic and that in later years this species had almost disappeared from Swedish Lapland. Jackass penguins (Spheniscus demersus), found only in South Africa, have suffered losses from pollution caused by oil traffic around the Cape of Good Hope (Stander and Venter 1968). Their total population was estimated at 100,000 in 1960, and in two separate but not isolated incidents 1 to 2% of this number were known to have been killed by oil. Unknown but considerable numbers were uncounted or were lost at sea. Colony nesters, including puffins (Fratercula arctica), razorbills (Alca torda), and murres in the southerly portions of the North Sea are declining rapidly (Nelson-Smith 1972). Puffins, which numbered 100,000 on Annet in the Scilly Isles in 1907, were reduced to 100 birds by 1967; by then, colonies farther east on the Great Britain coast were already extinct. Pollution from the Torrey Canyon disaster alone killed five-sixths of the puffins in the main French colony on the Sept Isles in Brittany and reduced the razorbills to a mere 50 birds, one-ninth of previous numbers (Bourne 1970).
There is every reason to believe that similar reductions in numbers could occur along the tanker route from Valdez to Puget Sound, with localized extirpation of colonies. Even more disastrous, however, would be an inopportune well blowout or other major spill in arctic waters. Massed concentrations of birds, already stressed by severe weather and food shortages, would be extremely vulnerable to this type of situation.
As pointed out by Nelson-Smith (1972), peculiarities of bird behavior determine, to some extent, the vulnerability of a species to oil spills. Auks, murrelets, and puffins (all Alcidae), loons (Gavia spp.), grebes (Podiceps spp.), and diving ducks may be most susceptible to oiling. Auks and loons, because they float low in the water, may more readily become completely covered by oil. Diving species that become flightless during their molt, such as alcids and waterfowl, or which do not fly because of social bonds between adults and flightless young (common murre) and spend most of their lives on the water, would be particularly vulnerable (J. M. Scott, comments by Pacific Seabird Group on U.S. Department of the Interior Draft Environmental Statement 74-90). All divers can easily surface into oil, and their reaction is to dive again, which in a large spill could result in surfacing into more oil. Phalaropes (Phalaropus spp.), which flock to feed in eddies which concentrate drift, may similarly be vulnerable to adverse effects of oil that would also concentrate in these areas. On the other hand, gulls swimming along the surface are likely to take wing before becoming seriously contaminated.
Nelson-Smith (1972) reported that gannets (Morus bassana), which collected oiled sea-weed for building nest mounds, contaminated themselves and their eggs. Behavioral problems associated with oil spills can be more subtle, however, and Darling's (1938) conclusions that the display of adjacent males contributes to stimulation of the female during courtship in seabirds breeding in massed colonies, is a good example. If Darling was correct, this behavioral characteristic could further impede the recovery of a population of auks, for example, from mortalities resulting from catastrophic losses to spills.