Thesis (M.S.)--Kutztown University of Pennsylvania, 1985. / Source: Masters Abstracts International, Volume: 45-06, page: 3047. Typescript. Abstract precedes thesis as preliminary leaves [1-2] Includes bibliographical references (leaves 64-66).

Thesis (M.S.)--University of North Texas, Dec., 2007. / Title from title page display. Includes bibliographical references.

Raptor rehabilitation has become commonplace globally, yet studies on the survival and adaptation of great horned owls (Bubo virginianus) after release has been neglected to an appreciable extent. The primary objective of this study is to provide quantitative data on the success of rehabilitated and released great horned owls in the North Texas region. Owls (N=12) were rehabilitated and released onto the Ray Roberts Greenbelt Corridor in Denton County, Texas, and monitored using radio telemetry to evaluate home range (November 2002 - February 2005). With approximately 75% of the birds released for this study surviving until transmitter battery failure, it is believed that the rehabilitation process was successful for these birds.

Graduation date: 1993

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.)

No description available.

Information was collected on the nesting ecology of the Great Horned Owl, with particular emphasis placed on aspects of its population and distribution, territoriality and predation. The study was conducted for the two years, 1967 and 1968 in the Thorpe and Topliff hills of central western Utah. Nesting densities on the study area were .36 pairs per square mile in 1967 and .40 pairs per square mile in 1968. Nests averaged one mile apart and were distributed in the periphery of the hills, overlooking the desert valleys. Favorite nest sites were cliff niches, but abandoned quarries and junipers were also utilized. Territorial studies of three nesting pairs indicate that these owls maintained hunting areas ranging from 172 acres to 376 acres in coverage. Owls ranged as far as one mile into the adjacent desert valleys, but extended little activity into the mountainous interior. The black-tailed jackrabbit and desert cottontail contribute the bulk of the Horned Owl food, followed by the kangaroo rat. Other mammals, birds and invertebrates are also utilized, but to a lesser extent.