Increased egg–nest visual contrast does not induce egg ejection in the eastern phoebe (Sayornis phoebe), an accepter host of the brood parasitic brown-headed cowbird (Molothrus ater).

2019 ◽  
Vol 133 (1) ◽  
pp. 46-55 ◽  
Author(s):  
Zachary Aidala ◽  
Bill M. Strausberger ◽  
Mark E. Hauber
Keyword(s):  
Molothrus Ater ◽  
Egg Ejection ◽  
Visual Contrast ◽  
Sayornis Phoebe ◽  
Eastern Phoebe

Site selection and repeatability in Brown-Headed Cowbird (Molothrus ater) parasitism of Eastern Phoebe (Sayornis phoebe) nests

2001 ◽  
Vol 79 (8) ◽  
pp. 1518-1523 ◽  
Author(s):  
Mark E Hauber
Keyword(s):  
Reproductive Success ◽  
Breeding Season ◽  
Site Selection ◽  
Molothrus Ater ◽  
Structural Failure ◽  
Sayornis Phoebe ◽  
Eastern Phoebe ◽  
Site Discrimination

The reproductive success of obligate brood parasitic birds depends on their ability to seek out heterospecific nests. Some nests are more suitable for parasitism than others and, for example, parasitic females may benefit from laying eggs preferentially and repeatedly at safer sites. Observations on patterns of Brown-headed Cowbird (Molothrus ater) parasitism on Eastern Phoebes (Sayornis phoebe) across 2 years suggested that parasitism occurred at above chance levels during the first rather than the second nesting attempts and at nests located under eaves rather than bridges. Previously parasitized nests were more likely to be parasitized again in the subsequent breeding season. Sites under eaves and bridges did not differ in whether Brown-headed Cowbirds could be detected in the proximity of the nest. However, nests from first nesting attempts and nests under eaves were less likely to be lost as a result of structural failure of the Eastern Phoebe's mud nest. These data suggest that site discrimination by Brown-headed Cowbirds leads to adaptive patterns of parasitism among available Eastern Phoebe nests.

scholarly journals Eastern Bluebirds Eject Brown-Headed Cowbird Eggs

The Condor ◽  
2006 ◽  
Vol 108 (3) ◽  
pp. 741-745 ◽  
Author(s):  
Brian D. Peer ◽  
Lyndon R. Hawkins ◽  
Edwin P. Steinke ◽  
Patricia Blair Bollinger ◽  
Eric K. Bollinger
Keyword(s):  
Selective Pressure ◽  
Molothrus Ater ◽  
Conspecific Brood Parasitism ◽  
Sialia Sialis ◽  
Eastern Bluebird ◽  
Egg Ejection ◽  
Cavity Nesting ◽  
Eastern Bluebirds ◽  
Cowbird Parasitism ◽  
The Relationship

Abstract The relationship between the Brown-headed Cowbird (Molothrus ater) and its cavity-nesting hosts has received little attention because of the assumption that cowbirds rarely parasitize these hosts. We tested the Eastern Bluebird (Sialia sialis), a host that is sometimes heavily parasitized by cowbirds, for egg ejection behavior. Bluebirds ejected 65% of experimentally added cowbird eggs (n  =  20), but ejected no experimentally added conspecific eggs (n  =  66). This suggests that cowbird parasitism, not conspecific brood parasitism, is the selective pressure responsible for egg ejection in this species. This level of rejection may be conservative because bluebirds nest in dark cavities, which may make cowbird eggs difficult to detect by bluebirds.

scholarly journals First Evidence of Conspecific Brood Parasitism and Egg Ejection in Song Sparrows, With Comments on Methods Sufficient to Document These

The Condor ◽  
2006 ◽  
Vol 108 (2) ◽  
pp. 452-458
Author(s):  
Quresh S. Latif ◽  
J. Letitia Grenier ◽  
Sacha K. Heath ◽  
Grant Ballard ◽  
Mark E. Hauber
Keyword(s):  
Genetic Analysis ◽  
Brood Parasitism ◽  
Nest Predation ◽  
Molothrus Ater ◽  
Separate Study ◽  
Conspecific Brood Parasitism ◽  
Egg Ejection ◽  
Song Sparrows ◽  
Cowbird Parasitism ◽  
Egg Marking

Abstract Conspecific brood parasitism occurs in many songbird species but has not been reported in Song Sparrows (Melospiza melodia). In three separate study areas where breeding Song Sparrows experience heavy nest predation pressure and Brown-headed Cowbird (Molothrus ater) parasitism, we observed six instances in which newly laid eggs were attributable to female Song Sparrows other than the nest owners. We also recorded the ejection of a sparrow egg from each of two videotaped nests. In a fourth study area without cowbird parasitism, genetic analysis of parentage revealed no conspecific brood parasitism. Given that egg ejection can accompany conspecific parasitism in Song Sparrows, we suggest that daily nest checks are insufficient to document the frequency of this tactic in some species in the absence of egg marking, videotaping, or genetic analyses. Since standard nest monitoring techniques may fail to detect conspecific brood parasitism, this behavior could be more prevalent than currently thought.

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