Global ETD Search
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Showing 1 to 19 of 19 for “"Molothrus ater"”.
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Nest Predation by brown-headed cowbirds (Molothrus ater)
… hypothesis for the brown-headed cowbird (Molothrus ater). I found evidence that cowbird attacks are not uncommon, a basic requirement of the hypothesis. Furthermore, I found multiple lines of evidence that cowbird attacks are not indiscriminate, but directed at non-parasitized nests and at …
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Breeding Behavior and Reproductive Success of Chipping Sparrows in Northwestern Minnesota
… predation. Parasitism by Brown-headed Cowbirds (Molothrus ater) caused a comparatively smaller loss in reproductive success. Four pairs raised two broods in one season. Males assumed nearly all care of first brood fledglings, freeing the female to build a second nest. This strategy of parental …
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Reproductive success of a generalist brood parasite predicts the rate of parasitism in the subsequent year
Brown-headed cowbirds (Molothrus ater) rely solely on hosts to raise their young. Although cowbirds parasitize 200+ species, recent evidence suggests that females avoid unsuitable hosts that either reject parasitic eggs or provide incompatible parental care. Female cowbirds may be able to improve …
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Mechanisms underlying population dynamics of a migratory songbird in a fragmented forest
… I studied the impact of Brown-headed Cowbird (Molothrus ater) brood parasitism and of nest predation on the reproductive success of Wood Thrush (Hylocichla mustelina) hosts in three large ($>$1000 ha) forest tracts in southern Illinois. In these forests, nests were typically …
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Population Dynamics of the Endangered Black-capped Vireo (Vireo atricapilla)
… rates of parasitism by the brown-headed cowbird (Molothrus ater) across its breeding range from northeastern Mexico to southern Oklahoma. The largest population located on the Fort Hood Military Reservation in central Texas is well-studied, but its role in landscape-level vireo population dynamics …
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Nest predation and habitat selection in the grasshopper sparrow (Ammodramus savannarum)
… as well. Nest losses attributed to cowbirds (Molothrus ater) were unrelated to measured habitat or landscape variables and unaffected by management actions. Though nest sites did not differ from available habitat, female grasshopper sparrows did exhibit adaptive nest-site selection by …
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Age-specific mortality, pre- to post-fledging carryover effects, and the timing of fledging in altricial songbirds
… period in a community of songbirds to provide greater insight into how age-specific mortality shapes avian ecology and life history evolution. Specifically, my research sought to (1) test for potential pre- to post-fledging carryover effects under a morphology-performance-fitness paradigm; (2) …
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Testing proximate causes and ultimate explanations of social cue use for habitat selection by songbirds
… an experiment with Brown-headed Cowbird models (Molothrus ater; a brood parasite that reduces reproductive success) revealed that Yellow Warblers behaved more aggressively towards cowbirds when apparent conspecific density was high. Results from these studies provide insight as to when, where, …
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Urbanization affects environmental conditions for developing songbirds
… how brood-parasitic brown-headed cowbirds (Molothrus ater) affect host clutch size and nest success. Host clutch sizes were lower when parasitized, but surprisingly non-parasitized nests were more likely to fail. Despite lower arthropod food availability and high levels of brood parasitism, …
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Survey of Nasal Mites (Acari: Rhinonyssidae, Ereynetidae, Turbinoptidae) in Birds from Three States in the United States
… from the brood parasite, brown-headed cowbird (Molothrus ater), in specimens from Texas and Arkansas. For this survey, 126 individuals were analyzed, and 84 (66.6 %) were found to be infested with nasal mites, which included new host records for the cowbirds. I addressed the question of whether …
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An Experimental Study of Behavioral Responses to Nest Predation and Brood Parasitism in a Migratory Songbird
… where brood parasitism by Brown-headed Cowbirds (Molothrus ater) and nest predation can greatly reduce reproductive success. I studied populations of Prothonotary Warblers (Protonotaria citrea) in a fragmented bottomland forest during 1993--2000 and conducted field experiments to determine if …
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Behavioral ecology of juvenile brown-headed cowbirds: implications for the evolution and maintenance of avian brood parasitism
… research on juvenile brown-headed cowbirds (Molothrus ater) to elucidate the factors that contribute to the evolution and persistence of avian brood parasitism. To avoid adopting the behaviors and mate choice preferences (sexual imprinting) of the foster species, juvenile cowbirds could …
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Using Occupancy Models to Predict Grassland Bird Distributions in Southeastern Alberta
… (Ammodramus bairdii), Brown-headed Cowbird (Molothrus ater), Chestnut-collared Longspur (Calcarius ornatus), Clay-colored Sparrow (Spizella pallida), Horned Lark (Eremophila alpestris), Long-billed Curlew (Numenius americanus), Marbled Godwit (Limosa fedoa), McCown's Longspur (Rhynchophanes …
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Effects of urbanization on the physiology, behavior, and fitness of a wild songbird
… other reproductive behaviors such as maternal care. Indeed, female song sparrows, like males, expressed increased aggressive signaling compared to rural, suggesting urban habitats may favor a more aggressive phenotype. Finally, in Chapter 3, I investigated the consequences of increased …
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Nesting ecology and conservation of shrubland birds in a fragmented urbanized landscape in northeastern Illinois
… and abandonment due to Brown-headed Cowbird (Molothrus ater) parasitism were also documented. All nests experiencing Brown-headed Cowbird parasitism failed (n=5). Red-winged Blackbird (Agelaius phoeniceus) was one of the most successful species; Willow Flycatcher (Empidonax traillii) was one …
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Incidence, mechanisms, and consequences of adaptive habitat selection by the dickcissel (Spiza americana)
… avoid parasitism by brown-headed cowbirds (Molothrus ater), and produce robust offspring. Dickcissels engaged in adaptive habitat selection in some respects—such as preferring territories associated with high offspring condition and patches where parasitism was infrequent—but there was …
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Influence des oiseaux noirs sur la faune des coléoptères de trois champs de mais fourrager de la station de recherches de Lennoxville, P. Québec, Canada
… (QuisaaZus quisaula L.), le vacher à tête brune (Molothrus ater B.) fréquentent les champs de maïs fourrager. Une estimation des volées de ces oiseaux faites lors des semis et de l'épiaison du maïs démontre qu'il n'y a pas de changements dans la densité de Q. quisaula et M. ater; celle-ci d'A. …
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The role of individual variation in auditory and visual processing: implications for mate choice
… questions using the brown headed cowbird (Molothrus ater) as a model species: (i) how does male signaling behavior differ with the sex of the receiver? (ii) how do components within a signal combine to generate a response by the female, (iii) how is female sensory capacity in one modality …
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An integrative approach to testing density effects in a migratory songbird, the Prothonotary Warbler (Protonotaria citrea)
… common brood parasite, the Brown-headed Cowbird (Molothrus ater), to improve warbler nesting success and increase their densities. The resultant range of densities (1-27 neighbors/pair) were at or beyond that seen under natural conditions in this system. Each year, I estimated warbler reproductive …