Veery

Catharus fuscescens (Stephens)

Although the veery subspecies C. fuscescens salicicola was previously known to be parasitized by the brown-headed cowbird, a new picture of the extent to which it is imposed upon in the western prairie provinces of Canada is revealed by the files of the Prairie Nest Records Scheme which include 14 such instances in Alberta, Saskatchewan, and Manitoba, out of a total of 28 nests reported, or an incidence of 50 percent. These records suggest some geographical difference in the frequency of parasitism. In Alberta and Manitoba 8 nests were reported, all but 1 of which were parasitized, while in Saskatchewan 20 nests were reported, 7 of which (35.0 percent) had cowbird eggs or young in them.

One of us (S.I.R.) noted 2 additional cases of parasitism among 3 nests of this thrush found near Delta, Manitoba, in late June and July 1970. When found, 1 of the nests had 3 veery nestlings, 1 cowbird nestling, and 1 veery egg. The other nest eventually held 1 veery egg and 4 cowbird eggs although initially 3 veery eggs were present with the 4 of the cowbird. The single veery egg left in the nest hatched on 3 July, even though its shell had 3 or 4 small holes in it 4 days earlier, presumably inflicted by an adult cowbird. The nest was destroyed by a predator before any of the cowbird eggs hatched. That the veery may be prone to multiple parasitism is suggested by Harrison's experience (1975:161); he found 3 parasitized nests at Oconto, Wisconsin, containing 3, 3, and 5 cowbird eggs, respectively.

In the collections of the Western Foundation, 5 (9.6 percent) of 52 sets of eggs of this species are parasitized. The Ontario nest records files at Toronto have data on 139 nests, 28 of which (20.1 percent) were parasitized.

EASTERN BLUEBIRD