House Sparrow

Passer domesticus (Linnaeus)

That the house sparrow is only a very occasional host choice of the brown-headed cowbird is suggested by the small number of definite records of parasitism out of many hundreds of nests examined (742 in Ontario alone, none of them parasitized), and especially by the fact that in most areas only single instances have been reported—1 each from California, Kentucky, Maryland, New York, and Ohio, and 2 each from Colorado and Michigan. In the 1963 compilation (Friedmann, p. 125) were noted indefinite statements of “regular” parasitism of house sparrows in Pennsylvania and in eastern Kentucky, but no numbers or cases were given in their original support. To all these we may add the following: Bull (1974:537) lists 2 more instances from New York; “Woods” (1972:14–15) mentions 1 from Kansas; Bennett (1973:9) reports 1 from Nebraska; and Wauer (1973:178) lists the house sparrow as a cowbird host in the Big Bend National Park, Texas. This last record involves the race M. ater obscurus of the parasite, previously noted but a single time in this relationship—in southern California (Friedmann, 1963:125).

The fact that the eggs of the house sparrow and of the brown-headed cowbird are quite similar may have caused other cases of parasitism to remain undetected.

BOBOLINK

Passer domesticus (Linnaeus)

This introduced, but now widely distributed, species was previously known to have been parasitized once in Chile by the shiny cowbird. Sick informs us of a similar record from Sao Paulo, Brazil. In an earlier paper (1957:16–17) Dr. Sick reported that around Rio de Janeiro he found house sparrows and shiny cowbirds congregating in mixed flocks and sleeping together in small roosts, but at that time he wrote that the house sparrow had not been known to be used as a host by the parasite. Judging by the more extensive data on this bird in North America, the house sparrow seems unlikely to become a regular host choice. Its pugnacity alone would be a deterrent to the would-be intruder. The Brazilian record involves the cowbird race M. bonariensis melanogyna; the earlier Chilean one had to do with M. bonariensis bonariensis.

CRESTED OROPENDOLA