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COSEWIC Assessment and Update Status Report on the Ross’s Gull in Canada

Limiting Factors and Threats

Industrial Activity

Oil development in the Beaufort and Chukchi Seas poses a potential threat (Burger and Gochfeld 1996, Alvo et al. 1996). The concentrations of birds during September and October as they head east into the Beaufort Sea, and then west into the Chukchi and Bering Seas makes the species particularly vulnerable to oil spills, either directly as oil accumulation on the bird itself or in impacting prey availability (Alvo et al. 1996). Breeding sites in Canada are relatively remote and are not at risk from industrial development at present, although there are significant oil and gas reserves in the Canadian Arctic that might be exploited at some future date.

Climate Change

Given the rate at which climate change is affecting the Arctic, any obligate Arctic-adapted species should be considered under imminent threat (A.J. Gaston, pers. comm. 2006). Annual snow and ice patterns are probably major limiting factors influencing the decision to breed in any given year, since one critical variable is the presence of open water close to the nesting site. Weather events such as floods and periods of cold weather may also decrease reproduction substantially (Macey et al. 1981); in 1986, a heavy rainstorm killed five of six hatched chicks in a population in Siberia (Densley 1988). Climate change, therefore, represents an unknown effect on the reproductive ecology of Ross’s Gulls.

Human Disturbance

Disturbance by humans is a potential threat to the Ross’s Gull in Canada (Macey 1981). The discovery of Ross’s Gulls at Churchill in 1978 has resulted in Churchill being among the most popular of Arctic and subarctic locations for bird-watchers and photographers to visit (Hamel 2002). At least one nest was abandoned because a photographer was too close (Alvo et al. 1996). However, Ross’s Gulls are reported to nest successfully beside hunting camps in Russia (Alvo et al 1996), whereas observers within 100 m from a nest are reported to disturb the gulls (Béchet et al. 2000).

In the Churchill area, there have been persistent reports of nests upstream from the end of the Hydro Road (R. Koes, pers. comm. 2006). Although more remote than the Akudlik site, the new sites are still vulnerable to disturbance from airboats and helicopters travelling south along the river. The remoteness of breeding sites in Nunavut offers some protection to nesting Ross’s Gulls.

There likely still is a black market for the sale of Ross’s Gull eggs; a Ross’s Gull egg was apparently a valuable acquisition for oologists, with an estimated value of $10,000 to $20,000 on the black market in the early 1980s (Alvo et al. 1996). The theft of a nest and eggs in 1981 bears testament to the ongoing trafficking in bird’s eggs (Alvo et al. 1996).

Habitat Destruction

Of the four known nesting localities of Ross’s Gulls in Canada, the three High Arctic sites are probably fairly immune to possible habitat alteration but the known sites at Churchill are potentially vulnerable. Reports that Manitoba Hydro flooded the Akudlik Marsh in 1984 (Alvo et al. 1996) appear to be groundless. Why the shift in nesting locations at Churchill occurred remains undetermined.