Host Relations of the Parasitic Cowbirds

Friedmann, Herbert

doi:10.5479/si.03629236.233

Cited by 153 publications

(115 citation statements)

References 4 publications

(4 reference statements)

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“…First, song sparrows are among the cowbird's five most common hosts (1,2), and their nesting chronology resembles that of many hosts (8,(18)(19)(20)(21)(22)(23)(24). It is plausible, therefore, that the behavior we ascribe to cowbirds occurs elsewhere.…”

Section: Resultsmentioning

confidence: 99%

“…Nest predation may also improve a cowbird's ability to synchronize its own laying with that of its host. This is because most common hosts are territorial and, barring renesting dispersal, will renest within 5-7 days of nest failure (1,8,(18)(19)(20)(21)(22)(23). The potential benefits of nest predation to cowbirds are thus analogous to those of sexually selected infanticide in other species (24,25).…”

mentioning

confidence: 99%

“…Brown-headed cowbirds (Molothrus ater) are brood parasites of over 220 species of North American passerines and are thought to reduce host productivity, mainly because adults remove host eggs and nestlings usurp host parental care (1,2). Nest predation also reduces productivity in cowbird hosts, and parasitism and predation have been jointly linked to population declines in several species, including threatened and endangered neotropical migrants (3)(4)(5)(6)(7)(8)(9).…”

mentioning

confidence: 99%

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Nest predation by cowbirds and its consequences for passerine demography.

Arcese

Smith

Hatch

1996

Proc. Natl. Acad. Sci. U.S.A.

173

112

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Brood parasitism by brown-headed cowbirds (Molothrus ater) reduces reproductive success in many passerines that nest in fragmented habitats and ecological edges, where nest predation is also common. We tested the hypothesis that parasitism and predation are often linked because cowbirds depredate nests discovered late in the host's nesting cycle to enhance future opportunities for parasitism. Over a 20-year study period, brood parasitism by cowbirds was a prerequisite to observing marked inter-and intraannual variation in the rate of nest failure in an insular song sparrow (Melospiza melodia) population. Nest failure increased with the arrival and laying rate of cowbirds and declined when cowbirds ceased laying. The absence or removal of cowbirds yielded the lowest nest failure rates recorded in the study. The absence of cowbirds also coincided with the absence of an otherwise strong positive correlation between host numbers and the annual rate of nest failure. Host numbers, cowbird parasitism, and nest failure may be correlated because cowbirds facilitate nest failure rather than cause it directly. However, an experiment mimicking egg ejection by cowbirds did not affect nest failure, and, contrary to the main prediction of the predation facilitation hypothesis, naturally parasitized nests failed less often than unparasitized nests. Higher survival of parasitized nests is expected under the cowbird predation hypothesis when female cowbirds defend access to hosts because cowbirds should often depredate unparasitized nests but should not depredate nests they have laid in. Where female cowbirds have overlapping laying areas, we expect parasitized nests to fail more often than others if different cowbirds often discover the same nests. We suggest that nest predation by cowbirds represents an adaptation for successful parasitism and that cowbirds influence host demography via nest predation.Brown-headed cowbirds (Molothrus ater) are brood parasites of over 220 species of North American passerines and are thought to reduce host productivity, mainly because adults remove host eggs and nestlings usurp host parental care (1, 2). Nest predation also reduces productivity in cowbird hosts, and parasitism and predation have been jointly linked to population declines in several species, including threatened and endangered neotropical migrants (3-9). This link is currently believed to be a coincidental result of the preferences of nest predators and cowbirds for fragmented habitats and ecological edges (10-15).In contrast, we have argued that cowbirds regularly depredate nests that are discovered too late in the host's nesting cycle to be suitable for parasitism, because this enhances future laying opportunities (16,17). Nest predation may also improve a cowbird's ability to synchronize its own laying with that of its host. This is because most common hosts are territorial and, barring renesting dispersal, will renest within 5-7 days of nest failure (1,8,(18)(19)(20)(21)(22)(23). The potential benefits of nest predatio...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Nest predation by cowbirds and its consequences for passerine demography.

Arcese

Smith

Hatch

1996

Proc. Natl. Acad. Sci. U.S.A.

173

112

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“…Brood parasitism of Field Sparrow nests by Brown-headed Cowbirds (Molothrus ater) is common (Friedmann 1963, Friedmann et al 1977. Parasitism rates vary from <1% of 371 nests (M. Carey in Carey et al 1994) to 80% of 20 nests (Crooks 1948, Crooks andHenderson 1953).…”

Section: Brown-headed Cowbird Brood Parasitismmentioning

confidence: 99%

Effects of management practices on grassland birds: Field Sparrow

Dechant¹,

Sondreal²,

Johnson³

et al. 1999

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“…Brood parasitism by Brown-headed Cowbirds (Molothrus ater) appears to be infrequent in Upland Sandpiper nests (Friedmann 1963, Friedmann andKiff 1985). Documented rates of 7 parasitism are 0% of 28 nests (M. Winter and D. H. Johnson, unpublished data), 1% of 189 nests (Higgins and Kirsch 1975), and 5% of 43 nests (Faanes and Lingle 1995).…”

Section: Brown-headed Cowbird Brood Parasitismmentioning

confidence: 99%