Sunrise Nest Attentiveness in Cowbird Hosts

Neudorf, Diane L. H.; Sealy, Spencer G.

doi:10.2307/1369073

Cited by 86 publications

(51 citation statements)

References 24 publications

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“…Therefore, we would expect parasitism on at least the solitary nesting grackles. Neudorf and Sealy (1994) also found that Common Grackles only were present at their nests for approximately half of the 30-minute time period during which cowbirds were most likely to parasitize them. Thus grackle nests are vulnerable to parasitism.…”

Section: Discussion Breeding Season Phenologymentioning

confidence: 83%

Explanations for the Infrequent Cowbird Parasitism on Common Grackles

Peer

Bollinger

1997

The Condor

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Abstract. We determined the factors responsible for the lack of parasitism on Common Grackles (Quiscalus quiscula) by Brown-headed Cowbirds (Molothrus ater). We found no evidence of parasitism on the 401 grackle nests we monitored in east-central Illinois. By the time cowbirds began laying eggs, 88.5% of all grackle nests were beyond the point of successful parasitism. Grackles rejected cowbird eggs more frequently during the prelaying stage of the nesting cycle (38.2%) compared to later stages (12.3%). Thirty-three cowbird eggs and nestlings were cross-fostered into grackle nests. Data were collected on 15 cowbird nestlings, of which three fledged. The cross-fostered cowbird eggs that did not hatch appeared to have been incubated ineffectively. These eggs were in clutches that contained four to six eggs, whereas the cowbird eggs that hatched were in clutches of three eggs or less. Grackles also responded more aggressively toward female cowbird models than to Fox Sparrow (Passerella iliaca) models in five of seven response categories. Cowbirds avoid parasitizing grackles even though the opportunity existed. Nest abandonment and infestation of grackle nests with ectoparasitic mites may decrease the suitability of grackles as hosts; however the primary reason for the infrequent cowbird parasitism on grackles appears to be past rejection behavior. Grackles likely rejected cowbird eggs at a higher frequency in the past and as a consequence grackles were avoided by cowbirds. Rejection apparently decreased in the absence of parasitism due to the high degree of intraclutch egg variability exhibited by grackles which would increase the chances of them mistakenly rejecting their own discordant eggs.

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Section: Discussion Breeding Season Phenologymentioning

confidence: 83%

Explanations for the Infrequent Cowbird Parasitism on Common Grackles

Peer

Bollinger

1997

The Condor

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“…Being on the nest at dawn might be one defense against parasitism [9]; however, these authors [9] found no correlation between sunrise nest attentiveness and frequency of parasitism in a community of ten potential cowbird hosts in Manitoba, including the cowbird-accepting Least Flycatcher (Empidonax minimus). Despite being off the nest during the critical period of clutch initiation, parasitism of the Least Flycatcher was very low [9]. Sealy et al [49] found that sunrise nest attentiveness may be a function of incubation rather than a specific response to parasitism in the Yellow Warbler (Setophaga petechia).…”

Section: Nest Attentivenessmentioning

confidence: 97%

“…Individuals that accept parasitic eggs in their nests for five days were considered to be acceptors [1,39]. Each pewee nest was in the egg-laying or early incubation stage, and eggs were placed in nests before noon because cowbirds typically parasitize nests in the morning [9,39,40]. One cowbird egg was left in a nest to determine whether pewees could hatch a cowbird egg.…”

Section: Egg Ejectionmentioning

confidence: 99%

“…However, for an avian community made up of several suitable host species (i.e., able to fledge cowbird young) parasitism rates among these species can be quite variable. Several factors that may explain these differences in parasitism rates include nest placement and nest concealment [5,6], nest defense [7,8], nest attentiveness [9], ejection of foreign eggs from the host nest [10,11], nest abandonment [12][13][14], spatial nesting pattern such as colonial nesting [15,16], host activity during nest building [17], overlap of the nesting cycles of cowbird and host [18], and host quality [19].…”

Section: Introductionmentioning

confidence: 99%

“…Ejection of cowbird eggs is a relatively uncommon yet effective parasite defense [9,26,27], whereby the host removes the cowbird egg from the nest by grasp-, or punctureejecting [1,27]. In New Mexico, Curson et al [28] demonstrated experimentally an 80% cowbird egg acceptance rate by pewees in a habitat where pewees naturally sustain a 16% parasitism rate.…”

Section: Introductionmentioning

confidence: 99%

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Differential Parasitism Between Two Suitable Cowbird Hosts

Walsh¹,

Tuff²,

Cruz³

et al. 2015

TOOENIJ

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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.

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