Hatching asynchrony, nestling competition, and the cost of interspecific brood parasitism

Mark E. Hauber

Behavioral Ecology, 2003, vol. 14, issue 2, 227-235

Abstract: All parental hosts of heterospecific brood parasites must pay the cost of rearing non-kin. Previous research on nest parasitism by brown-headed cowbirds (Molothrus ater) concluded that competitive superiority of the typically more intensively begging and larger cowbird chick leads to preferential feeding by foster parents and causes a reduction in the hosts' own brood. The larger size of cowbird nestlings can be the result of at least two causes: (1) cowbirds preferentially parasitize species with smaller nestlings and lower growth rates; and/or (2) cowbirds hatch earlier than hosts. I estimated the cost of cowbird parasitism for each of 29 species by calculating the difference between hosts' published brood sizes in nonparasitized and parasitized nests and using clutch size to standardize values. In this analysis, greater incubation length and lower adult mass, surrogate measures of the hatching asynchrony and size difference between parasite and hosts, were both related to greater costs of cowbird parasitism without bias owing to phylogeny. To establish causality, I manipulated clutch contents of eastern phoebes (Sayornis phoebe) and examined whether earlier hatching by a single cowbird or phoebe egg reduces the size of the rest of the original host brood. As predicted, greater hatching asynchrony increased the proportion of the original phoebe brood that was lost. This measure of the cost of parasitism was partially owing to increased hatching failure of the original eggs in asynchronous broods but was not at all related to the size differences of older and younger conspecific nestmates. However, proportional brood loss owing to an earlier hatching conspecific was consistently smaller than brood loss owing to asynchronous cowbirds in both naturally and experimentally parasitized phoebe nests. These results imply that although hatching asynchrony is an important cause of the reduction of host broods in parasitized clutches, competitive features of cowbird nestlings remain necessary to explain the full extent of hosts' reproductive costs caused by interspecific brood parasitism. Copyright 2003.

Keywords: asynchronous hatching; brood reduction; host-parasite interaction; parental care (search for similar items in EconPapers)
Date: 2003
References: Add references at CitEc
Citations: View citations in EconPapers (2)

Downloads: (external link)
http://hdl.handle.net/ (application/pdf)
Access to full text is restricted to subscribers.

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:oup:beheco:v:14:y:2003:i:2:p:227-235

Ordering information: This journal article can be ordered from
https://academic.oup.com/journals

Access Statistics for this article

Behavioral Ecology is currently edited by Louise Barrett

More articles in Behavioral Ecology from International Society for Behavioral Ecology Oxford University Press, Great Clarendon Street, Oxford OX2 6DP, UK.
Bibliographic data for series maintained by Oxford University Press ().