Various physical and biological factors affecting annual productivity in a Red-tailed Hawk population in north-central Oregon were investigated. The percentage of the population successfully fledging one or more young was the most important factor in determining the number of young fledged per pair in a given year. Neither clutch size nor the number of young fledged per successful nest varied significantly. Percent pair success was correlated with several January weather variables. A cold and dry January is positively correlated with Red-tailed Hawk productivity. This is apparently related to the onset of rapid vegetative growth and this in turn is positively correlated with the timing of the emergence and reproductive cycle of the principal prey, Belding’s and Townsend's ground squirrels, (Turner 1972). Because a cold and dry January delays the emergence of ground squirrels, the period of emergence and dispersal of the young squirrels more closely corresponds to the time of peak food needs of the young Red-tailed Hawks, and greater pair success is observed. This relative abundance of prey appears to be of greater importance than actual abundance. Red-tailed Hawk productivity was found to correlate significantly with two habitat variables & the presence of adequate numbers of dispersed hunting perches and relative ground squirrel abundance. The presence of one or more perches per sixteenth section provided the best single correlation. Neither territory size nor competition from interspecifically territorial Swainson's Hawks were correlated with productivity of Red-tailed Hawk territories. Red-tailed Hawks with inhabited dwellings within their territories fledged significantly more young than those without.

In the Canadian prairies, native grasslands have been largely replaced by an agricultural landscape with a mosaic of habitats now better described as aspen parkland. Although habitat requirements of true prairie Buteo species, Swainson's (Buteo swainsoni) and ferruginous hawks (B. regalis), are relatively well identified, little is known about habitat use by red-tailed hawks (B. jamaicensis ) in this ecoregion. This study, evaluating productivity and habitat selection of red-tailed hawks breeding in aspen parkland, was conducted on Prairie Habitat Joint Venture (PHJV) assessment sites in central Saskatchewan in 1997 and 1998. Red-tailed hawk nesting densities and productivity were determined at three sites. Home ranges were mapped. Macrohabitat use and availability data were generated from digitized aerial photographs of PHJV assessment sites using a Geographic Information system. Microhabitat variables were measured in 0.04 ha plots centered on nests and random locations. (Abstract shortened by UMI.)

Thesis (Ph. D.)--University of Wisconsin--Madison, 2004. / Description based on print version record. Includes bibliographical references (leaves 133-135)

No description available.

A study was undertaken to determine the abundance, distribution, perching heights, diets and territory sizes of Red-Tailed Hawks on Sauvie Island, Oregon. Sauvie Island supported a large wintering population of non-territorial Red-Tailed Hawks. The establishment of territories began around 10 January. Average perch height was found to be 14.2 m. Average perch height increased from fall to spring, corresponding-to the onset of the breeding season and to the onset of egg-laying and incubation. Voles (Microtus spp.) were the principal prey year-round, though waterfowl were more important in terms of biomass in the winter and early spring. Territory sizes on the Island ranged from .31 - 3.73 km squared The abundance of voles was assessed in different habitats within five Red-Tailed Hawk territories. Territory size was shown to be inversely correlated to the population density of voles. The implications of this finding for the type of territoriality exhibited by Red-Tailed Hawks is discussed, as are some proximate factors affecting habitat selection.

The purpose of this study was to examine the hunting strategies of birds of prey in a probability learning situation. One great horned owl and one red-tailed hawk served as subjects. Three boxes and associated perches, each representing different potential prey areas, were placed in a room adjacent to the birds' regular housing and served as test apparatus. One box were required to land on a perch in order to gain access to the associated box and to the potential prey. A discrete-trial, self-correction procedure was used. In Experiment I, Box 1 was loaded with a live laboratory mouse on 60% of the trials, Box 2 on 30% of the trials, and Box 3 on the remaining 10%. A response requirement of sitting on the perch 5 seconds was programmed. In experiment II, the probability of reinforcement was reversed for the 10 and 60% boxes and the response requirement was increased from 5 to 20 seconds. Experiment III returned the probability of reinforcement for each box to the values used in Experiment I. In Experiment III the mice were euthanized prior to each trial. The owl matched responses to probability of reinforcement in all three experiments while the hawk matched in Experiment II and showed matching toward two of the three boxes in Experiment III. In Experiment I the hawk had a Box 2 preference. This research extends the generality of the matching concept and suggests that predatory birds do not randomly hunt or hunt in only one location, but rather tend to search according to the probability of reinforcement for that location.

Several species of raptors are found in prairie landscapes managed and enhanced for waterfowl. Red-tailed Hawks (Buteo jamaicensis ) and Great Horned Owls (Bubo virginianus) may benefit from such management in a manner that is counter to its goals and objectives; that is, waterfowl may comprise a significant proportion of their diet, resulting in a decline in waterfowl numbers. The overall aims of this three-year study were to determine whether the feeding habits of the two raptor species are selective and to determine if waterfowl is a preferred prey group. The diet was determined through pellet analysis, prey remains and direct nest observations during the nestling growth period. Availability of most prey species was assessed through small mammal trapping and by conducting waterfowl censuses. It was determined that both raptors select for duck species. The average waterfowl biomass consumed per nestling represented 21.5% of the total biomass consumed for Great Horned Owls and 23.5% for Red-tailed Hawks. (Abstract shortened by UMI.)

Thesis (M.S.) -- Mississippi State University. Department of Wildlife and Fisheries. / Title from title screen. Includes bibliographical references.

No description available.

abstract: Once considered an abundant species in the eastern United States, local populations of red-shouldered hawks, Buteo lineatus, have declined due to habitat destruction. This destruction has created suitable habitat for red-tailed hawks, Buteo jamaicensis, and therefore increased competition between these two raptor species. Since suitable habitat is the main limiting factor for raptors, a computer model was created to simulate the effect of habitat loss in central Maryland and the impact of increased competition between the more aggressive red-tailed hawk. These simulations showed urban growth contributed to over a 30% increase in red-tailed hawk habitat as red-shouldered hawk habitat decreased 62.5-70.1% without competition and 71.8-76.3% with competition. However there was no significant difference seen between the rate of available habitat decline for current and predicted development growth. / Dissertation/Thesis / M.S. Applied Biological Sciences 2011