c.s. photojournal

House sparrows (Passer domesticus) are not native to the U.S. and will steal cliff swallow’s (Petrochelidon pyrrhonota) mud nests. You can see the difference between the nest taken over by the house sparrow and the partially collapsed nest of the cliff swallow in one of the photos below: the sparrow will fill the nest with grasses (UC IPM). Here is a cute little article from 1936 on house sparrow parasitism by Dayton Stoner in The Wilson Bulletin (now called The Wilson Journal of Ornithology).

House sparrow swooping into the swallow’s mud nest which it has already filled with grasses.

The swallow in this photo is looking at the invader like GTFO.

Another house sparrow waiting to swoop in.

I’m not sure if the following is due to accidents on the part of the cliff swallows or purposeful acts on the part of the house sparrow nest invaders (I know little to nothing about birds), but definitely don’t go behind the bushes where these nests are located on campus (the east side of Regenstein). Later on in the summer, as witnessed last year, the ground is littered with dead baby birds.

Dead babies make me sad, so look at this picture of my dog when she was just a wee pup.