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Showing 1 to 20 of 34 for “"raptors"”.
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How well do buffer circles capture the ranging behaviours of territorial raptors?
… may be intense for apex predators, such as raptors, which generally require large natural areas in order to maintain their populations. Anthropogenic development within territories can cause individuals to either abandon these sites, reduce their breeding productivity, or cause direct …
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Responses of raptors to habitat fragmentation : from individual responses to population susceptibility
… attempted to explore the traits that predispose raptors to vulnerability from fragmentation. In this study, I compare the responses of two near-sympatric raptors (the Black Harrier Circus maurus and the Black Sparrowhawk Accipiter melanoleucus) to habitat fragmentation. On a broader scale, I use …
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Quantifying national abundance changes of raptors across Botswana using repeat road surveys
Raptors are a group of carnivorous birds experiencing considerable population declines across the globe. Despite these declines, many raptor populations remain poorly monitored across most of their ranges and, as with most biodiversity, this is especially true in developing countries, including …
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The Impact of Wind Turbines on the Distribution of Wintering and Migrating Raptors
… may negatively affect surrounding wildlife. Raptors are birds of prey and are potentially susceptible to being negatively affected by wind turbines. Raptor collisions with wind turbines are well-studied, but the potential for their spatial displacement due to wind turbines has received less …
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Vocal responses of Blue Jays (Cyanocitta cristata) to raptors that differ in predatory threat
… threats to Blue Jays in my study area, and other raptors used in my experiments, including American Kestrels (Falco sparverius), Cooper’s Hawks (Accipiter cooperii), Red-tailed Hawks (Buteo jamaicensis), and Great Horned Owls (Bubo virginianus), pose lesser threats. Although Blue Jays in my study …
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Prevalence and Identity of Tissue Cyst Forming Apicomplexan Parasites in the Muscles of Raptors
… protozoal infections in the tissues of raptors in the United States. Protozoan encephalitis caused by Sarcocystis species and Toxoplasma gondii is being increasingly reported in raptors from various locations in the United States. To better determine the exposure of raptors to these …
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Conservation of raptors and vultures in Botswana: with a focus on lappet-faced vultures Torgos tracheliotos
… including vultures, yet information on most raptors in this area is lacking. Along with the rest of the region, Botswana has seen a rise in poisoning incidences which have decimated vulture populations and threaten other scavenging raptor species. As a result, seven out of the nine …
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Raptors in Temperate Grasslands: Ecology of Ferruginous Hawk, Golden Eagle, and Northern Harrier in the Northern Great Plains
… (<em>Aquila chrysaetos</em>) are long-lived raptors with high nest-site fidelity and relatively low reproductive success. Population trends of golden eagles in western United States are unclear although long-term monitoring of populations shows declines in occupancy and breeding performance. …
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Are foraging patterns of aerial predators influencing diurnal activity of their prey?
… this study was to determine if aerial predators (raptors) influence diurnal activity patterns of their prey (mice). Sampling of both raptors and mice was done simultaneously during autumn, winter and spring at two different study sites in three different habitats on South Africa's arid west coast. …
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Raptor Use of the Idaho National Engineering Laboratory
<p>Raptors are high trophic-level predators, and thus sensitive to environmental change. I conducted a basic ecological study of raptors using the Idaho National Environmental Laboratory (INEL), in southeastern Idaho, between 1991 and 1993 to assess effects of human activity on the site. Results …
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Landscape and population ecology of ring-necked pheasants
… predator identity for 32. My results showed that raptors were the most common predators of pheasants. Both raptors and mesopredators were more likely to prey on pheasants in large fields than small ones. Predation by raptors could be minimized by increasing the amount of native grasses within …
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A Multi-Scale analysis of organochlorine pesticide contamination in raptor populations: research effort, historical trends, and current concentrations
… that species at higher trophic levels, like raptors, can act as valuable indicators of environmental pollutants. Raptors are quintessential apex predators, occupying top levels of the food chain in various ecosystems globally. Due to the well-known negative impacts of these pesticides on …
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Use of Eastern South Dakota Shelterbelts By Nesting Birds of Prey
… productivity, food habits, and ranges of raptors utilizing shelterbelts were in a 78 km² Brookings County study area. The shelterbelts were heterogeneous stands of trees and shrubsplanted in linear rows. Major tree species included elm (Ulmus spp.), green ash (Fraxinus pennsylvanica), …
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The mechanisms underlying convergent evolution in the plumage patterns of birds
… genera of Old World cuckoos and <8 sympatric raptors, I quantified their barred patterns using digital image analysis and found that parasitism can explain convergent evolution in the patterns of parasitic cuckoos and raptors. Patterns may have evolved due to ecological selection. Examining …
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Nest-site selection by Sharp-shinned Hawks in Kentucky
… secretive of North America's forest-breeding raptors, little is known about their breeding biology, including their preferred nesting habitat. In 2009 and 2010, I searched 248 forest stands in Kentucky and found 11 nests, all located in pines (Pinus spp.). Nests were at a mean height of 18.6 ± …
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Environmental factors influencing the breeding and health of a predator endemic to southern Africa: the endangered Black Harrier Circus Maurus
… As a group that occupies a high trophic level, raptors are particularly vulnerable to external changes and are generally regarded as useful indicators of ecological change. The Black Harrier Circus maurus is an avian predator endemic to southern Africa, which breeds essentially along the South …
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Important bird areas in the southern part of West Iceland
… waders, gulls and relatives. Passerine birds and raptors were present in low numbers. Most of the recorded species breed and nest in Iceland, but some passage migrants, vagrants and wintering guests were also seen. A total of 21,687 birds were seen and 49 species were recorded, of them 43 breeds …
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Factors affecting loggerhead shrike mortality in Virginia
… ages. More research is needed on the effects of raptors on shrike populations and on the role of foraging habitat on winter areas.
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Ecology of Gray Partridge in North Dakota
… mortality during these seasons was predation by raptors, mainly the great horned owl (Bubo virginianus). Roadsides were the most important nesting habitat. The best predictor of nest site availability in roadsides was presence of unmowed vegetation from the previous growing season. Available …
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A phylogenetic analysis of the Accipitridae (class Aves).
… the Accipitridae diverged from other diurnal raptors approximately 75 million years ago. Clades representing the major morphological diversity among the Accipitridae diverged about 40 million years ago over a period of approximately 7 million years.
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