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Showing 1 to 19 of 19 for “"Accipiter"”.
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A mechanistic approach to understanding the colour polymorphism in black sparrowhawks (Accipiter melanoleucus)
… evolutionary processes. The black sparrowhawk (Accipiter melanoleucus) occurs in two discrete colour variants: dark and light. The two morphs differ in the expression of white and black feathers on the breast, belly and underwing coverts. The morph has been associated with ambient …
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Exploring the breeding diet of the Black Sparrowhawk (Accipiter Melanoleucus) on the Cape Peninsula
… the diet of breeding Black Sparrowhawks (Accipiter melanoleucus) on the Cape Peninsula of South Africa. Macro-remains of prey were collected from below and around the vicinity of nests throughout the breeding seasons of 2012 and 2013. These prey items were then identified down to species …
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MHC Class I diversity influences haematozoon infection intensity in the polymorphic black sparrowhawk (Accipiter melanoleucus)
… explored in a population of black sparrowhawks (Accipiter melanoleucus). The species is of particular ecological and evolutionary interest as black sparrowhawks display a discrete polymorphism in plumage pattern across its range, occurring as a light and dark morph. It is well established in …
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Street-wise : does prey abundance buffer black sparrowhawks (Accipiter melanoleucus) from the negative health impacts of urbanisation?
… of the Western Cape, the Black Sparrowhawk (Accipiter melanoleucus) provides an excellent opportunity to explore some of these questions. In this study we explored how urbanisation may affect the health of this raptor on the Cape Peninsula, South Africa. If the health of this species is …
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Effects of Harvesting Ponderosa Pine on Birds in the Black Hills of South Dakota and Wyoming
… and unharvested stands. Sharpshinned hawks (Accipiter striatus), Cooper's hawks (Accipiter cooperii), northern goshawks (Accipiter gentilis), great-homed owls (Bubo virginianus), Swainson's thrushes (Catharus 11st11lat11s), and black-headed grosbeaks (Pheucticus melanocephalus) were detected …
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Responses of raptors to habitat fragmentation : from individual responses to population susceptibility
… Harrier Circus maurus and the Black Sparrowhawk Accipiter melanoleucus) to habitat fragmentation. On a broader scale, I use a simple model of susceptibility to fragmentation effects, and a sample of hawks (Accipiter spp) and harriers (Circus spp) in the family Accipitridae, to predict which …
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Factors influencing the timing of breeding in a range expanding raptor at two spatial scales
… In southern Africa, the Black sparrowhawk (Accipiter melanoleucus) originally existed in Botswana, Mozambique, North Eastern and South Eastern South Africa and Zimbabwe.
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Vocal responses of Blue Jays (Cyanocitta cristata) to raptors that differ in predatory threat
… (Megascops asio) and a Sharp-shinned Hawk (Accipiter striatus). I found no differences among trials in the characteristics (duration, low frequency, high frequency, and peak frequency) of either ditonal jeers or monotonal jeers. Assuming that calling rates vary relative to the degree of …
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Nest-site selection by Sharp-shinned Hawks in Kentucky
<p>Because Sharp-shinned Hawks (Accipiter striatus) are the most 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 …
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American Kestrels (Falco sparverius) may use tail-pumping to maintain balance
… of a conspecific and a predator (Cooper’s Hawk, Accipiter cooperi), I found no difference in likelihood of tail-pumping prior to and during the presentation. These results suggest that tail-pumping by American Kestrels is not used to communicate with conspecifics or as a predator-deterrent …
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The mechanisms underlying convergent evolution in the plumage patterns of birds
… (Cuculus canorus) and the Eurasian sparrowhawk (Accipiter nisus), but may be prevalent in Old World cuckoos. Randomly selecting a parasitic cuckoo from each genera of Old World cuckoos and <8 sympatric raptors, I quantified their barred patterns using digital image analysis and found that …
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The genetic basis of plumage polymorphism in the black sparrowhawk
… of plumage colouration in the black sparrowhawk (Accipiter melanoleucus), an African diurnal bird of prey. The adults of this species occur in two discrete morphs, light and dark. Light morph individuals were found to differ from dark morph individuals in the concentration of eumelanin in contour …
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Predicting Northern Goshawk Dynamics Using an Individual-based Spatial Model
The northern goshawk (Accipiter gentilis) is a US Forest Service Region 2 Sensitive Species, requiring the Black Hills National Forest to manage for its viability. Previous studies have suggested that a model integrating goshawk population demographics, habitat availability, and territoriality …
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Predicting Northern Goshawk Dynamics Using an Individual-based Spatial Model
The northern goshawk (Accipiter gentilis) is a US Forest Service Region 2 Sensitive Species, requiring the Black Hills National Forest to manage for its viability. Previous studies have suggested that a model integrating goshawk population demographics, habitat availability, and territoriality …
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The 2006 Warm Fire: effects on habitat and prey species of the northern goshawk
… of the forest habitats of the northern goshawks (Accipiter gentilis), a food-limited species of conservation concern, and the birds and mammals it feeds on. A conservation strategy for the species in the goshawk's food web in these forest types recommends restoring the mix of predator and prey …
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Prevalence and Identity of Tissue Cyst Forming Apicomplexan Parasites in the Muscles of Raptors
… encephalitis in an aviary in California. Hawks (Accipiter species) are believed to be the source of infection. The prevalence of T. gondii was 18.4% (21 of 114) in these birds by PCR, but none were positive by histopathology. N. caninum prevalence in raptors has been poorly discussed in the …
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MOVING THE GOALPOSTS: MIGRATORY BIRDS IN A CHANGING WORLD
… with both native avian predators such as hawks (Accipiter sp.) and abundant introduced predators such as free-roaming domestic cats (Felis catus), yet their behavioral responses to cats have been little studied during migration. Using an aviary experiment, I exposed wild Gray Catbirds Dumetella …
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A Study of Habitat Variables Associated with Northern Goshawk Nest Site Activity on the Three National Forests in Southern Utah
The Northern Goshawk has been a species of concern since its decline in the early 1990s, which has been attributed in part to loss of critical breeding and wintering habitat. Nest site selection of goshawks has been correlated with certain specific site characteristics including, but not limited …