Sialia currucoides (Bechstein 1798)

Sialia currucoides (Bechstein)

Dr. J. Lane informs us that 1 egg of the brown–headed cowbird was found with 3 of the mountain bluebird in a nest box 4 miles southwest of Kimnay, Manitoba, in July 1972. This is only the third record for this bluebird as a cowbird victim; the others were in Alberta and British Columbia (Friedmann, 1963:77; 1971:244). That the mountain bluebird is really an extremely unusual host is evidenced by the fact that the Brandon, Manitoba, junior bird students have erected 3500 bluebird nest boxes since 1959, at intervals of a few hundred feet, on tops of fence posts, for about 1000 miles in southwestern Manitoba, and this was the only instance of cowbird parasitism they noted. In 1971, 646 pairs of bluebirds, mostly mountain bluebirds, raised their young in these boxes and over 2600 nestlings were banded; in 1972, over 4100 nestling bluebirds were banded, with no young cowbirds among them. As mentioned in an earlier compendium (Friedmann, 1963:77), the British Columbia nest records scheme showed no instance of cowbird parasitism in their records of 115 nests of the mountain bluebird.

BLUE-GRAY GNATCATCHER