Translator Disclaimer
1 May 2000 COSTS OF PARASITISM INCURRED BY TWO SONGBIRD SPECIES AND THEIR QUALITY AS COWBIRD HOSTS
Author Affiliations +
Abstract

We measured the costs of Brown-headed Cowbird (Molothrus ater) parasitism incurred by Field Sparrows (Spizella pusilla) and Indigo Buntings (Passerina cyanea). We predicted that the frequent occurrence of nest desertion as a response to cowbird parasitism in Field Sparrows would be reflected by a higher cost of parasitism for that species. We also compared growth and survival of cowbird nestlings between hosts, predicting that they would do poorly at Field Sparrow nests because the latter appear to be avoided by cowbirds. Both species experienced reduced body mass gain in parasitized broods, but only Indigo Bunting suffered reduced tarsus growth. Both species experienced reductions in clutch size, hatching success, and nestling survival due to parasitism, but these losses did not differ among the two hosts. Multiple parasitism did not affect hatching success or nestling survival more than single parasitism for Indigo Buntings. Once accepted, cowbird offspring fared equally well in nests of both species, but almost half of all cowbird eggs laid in Field Sparrow nests were lost through nest abandonment. As parasitism costs to both species appear to be substantial, the rarity of nest desertion in Indigo Buntings may be due to other factors. Infrequent parasitism of Field Sparrows is consistent with host avoidance by cowbirds but other explanations should be explored.

Dirk E. Burhans, Frank R. Thompson III, and John Faaborg "COSTS OF PARASITISM INCURRED BY TWO SONGBIRD SPECIES AND THEIR QUALITY AS COWBIRD HOSTS," The Condor 102(2), 364-373, (1 May 2000). https://doi.org/10.1650/0010-5422(2000)102[0364:COPIBT]2.0.CO;2
Received: 14 August 1999; Accepted: 1 January 2000; Published: 1 May 2000
JOURNAL ARTICLE
10 PAGES


SHARE
ARTICLE IMPACT
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top