Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 22 for “"cowbirds"”.
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Nest Predation by brown-headed cowbirds (Molothrus ater)
… parasitism. I experimentally demonstrate that cowbirds determine the age of a nest by directly puncturing a portion of the clutch or indirectly by attending to the absolute number of eggs. Cowbirds also parasitized a high proportion of the re-nesting attempts following their attacks suggesting …
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Behavioral ecology of juvenile brown-headed cowbirds: implications for the evolution and maintenance of avian brood parasitism
… I conducted 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 …
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Development of new methods to investigate the role of the avian hippocampus in memory formation in brown-headed cowbirds
The hippocampus is known to participate in a variety of cognitive functions in humans, non-human primates, rodents, and birds. A great deal of previous research on the avian hippocampus has examined its role in spatial memory. A question regarding avian hippocampal function that remains unanswered …
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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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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 …
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The Effects of Global Change on Avian Biodiversity
… at risk of nest parasitism from Brown-headed Cowbirds, an obligate brood parasite. Because cowbird parasitism can reduce the reproductive success of the host species, some rare and endangered species have been managed with cowbird removals. I found that there are fewer cowbirds than expected …
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Assessing the Imprint of Geography, Host Species, Land Cover and Space on the Local Abundance of a Generalist Nest Parasite, the Brown-headed Cowbird
… species, and space on the local abundance of cowbirds. We used data from the North American Breeding Bird Survey, the National Land Cover Database, and the latitudinal/longitudinal coordinates of the bird survey routes to examine the effects that host species, land cover composition, and …
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Bird-like: five scenes for sinfonietta (or chamber orchestra)
… for food. The fourth scene, “Cardinals and Cowbirds,” begins with a hymn interlude, and is directly inspired by my interpretation of Audubon’s writings about these two species. Audubon characterizes cardinals as birds that inspire faith and security, and cowbirds (or “cow-pen birds”) as …
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Survey of Nasal Mites (Acari: Rhinonyssidae, Ereynetidae, Turbinoptidae) in Birds from Three States in the United States
… mites, which included new host records for the cowbirds. I addressed the question of whether cowbirds acquire nasal mites when the host parent is feeding its young, or whether mites are transferred during Social interaction of related birds that are commonly found in large, multi-species …
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Breeding Behavior and Reproductive Success of Chipping Sparrows in Northwestern Minnesota
… of nest 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 …
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Nest predation and habitat selection in the grasshopper sparrow (Ammodramus savannarum)
… forb cover 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 …
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Age-specific mortality, pre- to post-fledging carryover effects, and the timing of fledging in altricial songbirds
… if carryover effects occur in brood parasitic cowbirds. I found evidence for pre- to post-fledging carryover effects of wing development in all species I examined, with individuals with less developed wings exhibiting poorer flight ability and experiencing higher rates of mortality after …
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Testing proximate causes and ultimate explanations of social cue use for habitat selection by songbirds
… Warblers behaved more aggressively towards cowbirds when apparent conspecific density was high. Results from these studies provide insight as to when, where, and in what species to expect social cue use for habitat selection.
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Evolutionary dynamics of avian and non-avian limb morphology
… of adult and embryonic chickens, ducks, and cowbirds to test the following evolutionary hypotheses: 1) If patterns of covariance are determined predominantly by intrinsic factors, but these factors evolve over time (but not in relation to function), closely related species will have more …
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Urbanization affects environmental conditions for developing songbirds
… to investigate 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 …
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Passerine Use of Grasslands Managed With Two Grazing Regimes on the Missouri Coteau in North Dakota
… 29 in 1997. Grasshopper sparrows, brown-headed cowbirds, and clay-colored sparrows occurred most frequently on point counts. No differences occurred between grazing regimes for species richness or relative abundance in 1996. However, in 1997, rotational grazing systems had higher species …
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Landscape Fragmentation and Grassland Patch Size Effects on Non-game Grassland Birds in Xeric Mixed-grass Prairies of Western South Dakota
… sparrows, western meadowlarks, brown-headed cowbirds, chestnut-collared longspurs, bobolinks and red-winged blackbirds. Grasshopper sparrows and western meadowlarks were observed in >99% of grassland patches. Avian community composition was affected by landscape fragmentation and grassland …
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Effects of urbanization on the physiology, behavior, and fitness of a wild songbird
… of increase brood parasitism by brown-headed cowbirds (Molothrus ater) compared to rural. Overall increased urban aggression was associated with higher reproductive success without any reduction in paternal care. Additionally, we found physiological differences in the glucocorticoid stress …
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