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 15 of 15 for “"Brown headed cowbirds"”.
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Nest Predation by brown-headed cowbirds (Molothrus ater)
… predictions of this ‘farming’ 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 …
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Behavioral ecology of juvenile brown-headed cowbirds: implications for the evolution and maintenance of avian brood parasitism
… dissertation, 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, …
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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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Breeding Behavior and Reproductive Success of Chipping Sparrows in Northwestern Minnesota
… the incidence 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 …
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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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Urbanization affects environmental conditions for developing songbirds
… meta-analysis 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 …
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Passerine Use of Grasslands Managed With Two Grazing Regimes on the Missouri Coteau in North Dakota
… 30 in 1996 and 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 …
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An Experimental Study of Behavioral Responses to Nest Predation and Brood Parasitism in a Migratory Songbird
… fragmented landscapes 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 …
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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
… were: grasshopper 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 …
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Effects of urbanization on the physiology, behavior, and fitness of a wild songbird
… the added cost 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 …
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The Effects of Global Change on Avian Biodiversity
… species 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 …
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Incidence, mechanisms, and consequences of adaptive habitat selection by the dickcissel (Spiza americana)
… ability to attract mates, 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 …
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The role of individual variation in auditory and visual processing: implications for mate choice
… several specific research 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 …