Red-Winged Blackbirds and Brown-Headed Cowbirds: Some Aspects of a Host-Parasite Relationship

Freeman, Scott; Gori, David F.; Rohwer, Sievert

doi:10.2307/1368231

Cited by 62 publications

(50 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We also point out, however, that cowbirds employ different tactics to find nests (28) and that habitat structure may affect which of these tactics is employed most profitably (40)(41)(42) …”

Section: Resultsmentioning

confidence: 79%

Nest predation by cowbirds and its consequences for passerine demography.

Arcese

Smith

Hatch

1996

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

175

113

View full text Add to dashboard Cite

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...

show abstract

Section: Resultsmentioning

confidence: 79%

Nest predation by cowbirds and its consequences for passerine demography.

Arcese

Smith

Hatch

1996

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

175

113

View full text Add to dashboard Cite

show abstract

“…Although we found many nests in the nest-building stage (i.e., before the onset of egg laying), we summarize here only active nests, which we defined as nests attended by adults that contained at least one host or cowbird egg and/or nestling. We also found a few abandoned nests that contained cowbird eggs, but these are not reported because cowbirds are known to parasitize inactive nests (Freeman et al 1990). The presence of cowbird fledglings that were fed by adult hosts also was noted during the surveys of breeding birds, although an observation of a potential host feeding a cowbird fledgling does not establish conclusively the true foster-parentage of the fledgling cowbird (sensu Klein and Rosenberg 1986).…”

Section: Nests and Cowbird Parasitismmentioning

confidence: 92%

“…In this paper, we report cowbird densities and parasitism frequencies during two breeding-bird studies in the northern Great Plains: a statewide study in North Dakota (1992: Igl and Johnson 1997) and a Conservation Reserve Program (CRP) grassland study in nine counties of four states (1990-2006: Johnson and Schwartz 1993a, 1993bIgl andJohnson 1995, 1999;Igl 1995, 2001). We use data from nests found incidentally during both studies to examine weekly and annual variation in parasitism rates in the northern Great Plains, and nest data from the CRP grassland study to examine regional variation in parasitism rates.…”

mentioning

confidence: 99%

Brown-headed Cowbird, <em>Molothrus ater</em>, Parasitism and Abundance in the Northern Great Plains

Igl

Johnson

2007

Can Field Nat

View full text Add to dashboard Cite

The Brown-headed Cowbird (Molothrus ater) reaches its highest abundance in the northern Great Plains, but much of our understanding of cowbird ecology and host-parasite interactions comes from areas outside of this region. We examine cowbird brood parasitism and densities during two studies of breeding birds in the northern Great Plains during 1990–2006. We found 2649 active nests of 75 species, including 746 nonpasserine nests and 1902 passerine nests. Overall, <1% of nonpasserine nests and 25% of passerine nests were parasitized by Brown-headed Cowbirds. Although the overall frequency of cowbird parasitism in passerine nests in these two studies is considered moderate, the frequency of multiple parasitism among parasitized nests was heavy (nearly 50%). The mean number of cowbird eggs per parasitized passerine nest was 1.9 ± 1.2 (SD; range = 1–8 cowbird eggs). The parasitism rates were 9.5% for passerines that typically nest in habitats characterized by woody vegetation, 16.4% for grassland-nesting passerines, 4.7% for passerines known to consistently eject cowbird eggs, and 28.2% for passerines that usually accept cowbird eggs. The Red-winged Blackbird (Agelaius phoeniceus) was the most commonly parasitized species (43.1% parasitism, 49.6% multiple parasitism, 71.2% of all cases of parasitism). Passerine nests found within areas of higher female cowbird abundance experienced higher frequencies of cowbird parasitism than those found in areas of lower female cowbird abundance. Densities of female cowbirds were positively related to densities and richness of other birds in the breeding bird community.

show abstract

“…In Boulder County we have found only three parasitized pewee nests over 22 years of monitoring and none of those individuals have successfully fledged. By contrast, the Plumbeous Vireo (Vireo plumbeus; hereafter, "vireo") was parasitized at a 51% frequency (n = 292) [this study ; 19, 22], which is more typical of published parasitism rates throughout the vireo's range varying from *Address correspondence to this author at the Department of Biology and Biomedical Sciences, Salve Regina University, Newport, RI 02840, USA; Tel: 401-341-3204; Fax: 401-341-2993; E-mail: jameson.chace@salve.edu 32.3% to 87% depending on habitat [23][24][25]. In our study area, habitat cannot account for this difference in parasitism because both species live in close proximity to each other, within the same habitat and often occupying overlapping territories.…”

Section: Introductionmentioning

confidence: 83%

“…We examine aggression at the nest as well as nest attentiveness. Hosts that leave nests absent for extended periods are susceptible to cowbirds "freely" parasitizing their nests in the absence of any host response [32,33]. If hosts are attentive to the nest without outwardly revealing the nest, they may have an advantage over other hosts at deterring parasitism.…”

Section: Introductionmentioning

confidence: 99%

Differential Parasitism Between Two Suitable Cowbird Hosts

Walsh¹,

Tuff²,

Cruz³

et al. 2015

TOOENIJ

View full text Add to dashboard Cite

Abstract:Host choice by the brood parasitic Brown-headed Cowbird (Molothrus ater) is an evolved response to host suitability, resulting in patterns of differential parasitism rates among species within a community. In the ponderosa pine (Pinus ponderosa) forests of the Colorado Front Range, we recorded that Western Wood-pewee (Contopus sordidulus) is infrequently parasitized (1%, n = 259 nests) by the Brown-headed Cowbird, whereas the Plumbeous Vireo (Vireo plumbeus) is heavily parasitized (51%, n = 292). To account for differences in parasitism rates on these species we experimentally parasitized pewee nests with cowbird eggs, and we compared host aggression towards cowbird models, host nest attentiveness, nest placement, and egg-laying dates in these species. Pewees accepted cowbirds eggs and reacted more aggressively towards the cowbird model than the control model, were more attentive at their nest sites than vireos, and placed their nests higher and closer to the trunk than vireos. Egg-laying dates for vireos and cowbirds overlapped more than the egg-laying dates for pewees and cowbirds. We suggest that temporal asynchrony in host availability, coupled with differences in nest placement and behavior at the nest, help to account for the observed differences in parasitism rates between these two species.

show abstract

Red-Winged Blackbirds and Brown-Headed Cowbirds: Some Aspects of a Host-Parasite Relationship

Cited by 62 publications

References 16 publications

Nest predation by cowbirds and its consequences for passerine demography.

Nest predation by cowbirds and its consequences for passerine demography.

Brown-headed Cowbird, <em>Molothrus ater</em>, Parasitism and Abundance in the Northern Great Plains

Differential Parasitism Between Two Suitable Cowbird Hosts

Contact Info

Product

Resources

About