. The Canadian field-naturalist. . % Figure 1. An area where burrows of Leach's Storm-Petrels were dug out by Red Foxes (photo: W. A. Montevecchi) puffin out of a burrow in a grassy area among the ledges and carried it off. The Red Fox population on Baccalieu apparently includes two or more adult breeding pairs, as kits have been seen in most years, and two active dens were found in 1978. In winter, Willow Ptarmigan{Lagopus lagopus), a few small land birds, and berries may provide foxes with limited food. The vertical cliffs around the island's perimeter and absence of beaches preclude scaveng
. The Canadian field-naturalist. . % Figure 1. An area where burrows of Leach's Storm-Petrels were dug out by Red Foxes (photo: W. A. Montevecchi) puffin out of a burrow in a grassy area among the ledges and carried it off. The Red Fox population on Baccalieu apparently includes two or more adult breeding pairs, as kits have been seen in most years, and two active dens were found in 1978. In winter, Willow Ptarmigan{Lagopus lagopus), a few small land birds, and berries may provide foxes with limited food. The vertical cliffs around the island's perimeter and absence of beaches preclude scavenging on marine invertebrates and car- rion. Winter food shortages apparently keep the pop- ulation in check, and foxes may have to cache sizable quantities of seabirds to survive. No decline in seabird numbers in the 20 years foxes have lived on the island is evident, though such changes would not be easily detectable in view of the absence of standardized esti- mates of the large populations of burrow-nesters. Marine birds with low reproductive rates may be very seriously affected by additional sources of adult mor- tality. Petrels and puffins, whose nest-site selection patterns have evolved on islands free of land preda- tors, are particularly vulnerable to foxes; adults of cliff-nesting species are less likely to be preyed on even in areas accessible to foxes. The extirpation by foxes of any seabird species on Baccalieu Island seems unlikely. However, in view of depredations foxes have inflicted on seabird islands (Jones and Byrd 1979) and the apparent lack of alternative prey on Baccalieu, we conclude that systematic efforts should be made to assess the foxes' impact. The Canadian Coast Guard provided housing on Baccalieu, where E. Blundon, R. Hyde, F. Noonan, P. Rice, and L. Walsh offered hospitality. B. D. Harvey, I. R. Kirkham, and R. Purchase helped in searching the fox cache. K. Brink, I. R. Kirkham, D. Roby, and G. A. Sanger gave helpful criticism and information. Rese
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