Animal Sciences Commons^™

The Behavioral Causes Of Reproductive Skew In Cooperatively Polygynandrous Acorn Woodpeckers (Melanerpes Formicivorus), Anna C. Brownson

Biological Sciences Theses & Dissertations

Reproductive skew, the degree to which reproduction is shared among same-sex individuals in a social group, is a pattern affected by ecological conditions, sociality, cooperation, and the inter- and intrasexual behavior of individuals in complex animal societies. Transactional and compromise skew models assume that high skew is the product of dominance hierarchies among cobreeders, yet this has rarely been tested. Both model types fail to incorporate the decisions of more than two individuals, generally overlooking the effect of female behavior on male reproductive success in multi-male groups, and are ineffective at predicting skew in larger groups characterized by more than …

Rats As Forest Pests In Southeastern Virginia: Girdling By The Hispid Cotton Rat Sigmodon Hispidus As A Significant Source Of Mortality Of Loblolly Pines (Pinus Taeda) In A Successional Pine Forest, Robyn M. Nadolny

Biological Sciences Theses & Dissertations

The hispid cotton rat (Sigmodon hispidus) is a common field rodent throughout the southeastern US, where volunteer loblolly pine trees (Pinus taeda) invade open space and begin the process of ecological succession from field to pine forest. Recent analysis of the diet of S. hispidus indicates that loblolly pine bark is stripped and eaten during the winter months. In this study, we explored the extent of rodent girdling on a 1.23 ha grid in a successional pine forest in southeastern Virginia. During the winter of 2005 we observed damage to 65% of trees in our study area, with 98% …

Patterns Of Transience, Sex Bias, And Body Mass In Open-Habitat Rodent Populations, Stephen Edward Rice

Biological Sciences Theses & Dissertations

Rodents are assumed to live their lives in circumscribed (natal) areas with males being more prone to disperse than females and juveniles more prone to disperse than adults. To test these assumptions we examined the initial captures of geographic populations of hispid cotton rat, meadow vole, prairie vole, and marsh rice rat obtained through capture-mark-recapture methods. Capture records were obtained from Kansas and Illinois from long-term studies, and through live-trapping in Chesapeake, Virginia. I evaluated proportions of residents and transients, adults and juveniles, and males and females for significant differences among seasons, years, and geographic locations. The overall body masses …

Seasonal Variation In Diet Of The Cotton Rat (Sigmodon Hispidus) Based On Fecal Analysis, Lynn A. Walker

Biological Sciences Theses & Dissertations

Cotton rats, Sigmodon hispidus, live in oldfields, habitats with a variety of mostly herbaceous plants. Based on other studies, the hispid cotton rat eats predominantly grasses, but grasses rarely are the only food. Fecal samples were collected each month during an ongoing capture-mark-release demographic study of the rodent community at a location in southern Chesapeake, Virginia. In the lab, five fecal pellets per animal were stained, placed on a microscope slide, and covered with starch-gel medium and coverslip. Then a clear nail polish was applied to produce a semi-permanent slide. Using a microscope and a set of reference slides, plant …

The Effect Of A Predator Gradient On Female Oviposition Site Selection And Larval Performance, Josef F. Rieger

Biological Sciences Theses & Dissertations

Patterns of larval amphibian distribution and abundance have historically been ascribed to direct predation. However, adult oviposition site selection is an alternative mechanism that can produce identical patterns and significantly influence community assembly. Although such behavioral habitat selection has been documented in several amphibian species whose larvae lack particular anti-predator defenses, the sensitivity of adult amphibians in detecting predator cues and avoiding these habitats has not yet been determined. If larval survivorship is greatly reduced in sites containing predatory fish, selection to detect and avoid habitats with low fish densities should be strong. I conducted three experiments which, (1) evaluated …

Effects Of Human Disturbances On The Behavior Of Dabbling Ducks, Melissa Lynn Pease

Biological Sciences Theses & Dissertations

Disturbance of wintering and migrating birds by human activities can cause birds to expend energy in avoidance of humans and reduces the time available for resting and feeding at a time in the annual cycle when fat deposition and energy conservation are important. Also, human disturbances can effectively cause habitat loss by displacing birds from feeding or resting habitat. Managers of natural resources are increasingly faced with decisions about the types and amounts of public use that should be allowed without lowering the value of the resource for wildlife. In order for managers to make decisions about how to minimize …

An Analysis Of Migratory Behavior Physiological Condition And Life History Strategy In The Salamanders Ambystoma Mabeei And A. Opacum In Southeastern Virginia, Michael W. Mccoy

Biological Sciences Theses & Dissertations

Ambystoma mabeei is listed as threatened in Virginia due to its rarity and susceptibility to urbanization and poor forestry practices. The goal of this study was to identify factors that may affect the persistence of A. mabeei in Virginia by studying the life history and ecology of A. mabeei and its syntopic congener A. opacum. This information will contribute to the knowledge of life history variation within Ambystomatidae and will be critical for the development of a comprehensive management plan for A. mabeei. Population sizes of the two species and the proximate factors responsible for initiating breeding migrations were determined …

The Annual Reproductive Cycle Of Oryzomys Palustris In A Virginia Tidal Marsh, Erin A. Dreelin

Biological Sciences Theses & Dissertations

The objectives of my study were to determine when the marsh rice rat (Oryzomys palustris) begins and ends reproduction during the year, if there are seasonal changes in litter size, and the weight at which sexual maturity is reached. Monthly samples of rice rats were trapped from May 1995 to May 1996 in Northampton County, Virginia. Rice rats were trapped with Fitch live traps, euthanized in the field, and brought to the lab for necropsy. Data from two other studies of rice rats in Northampton County were also examined. Potential breeders did not reproduce with equal intensity throughout the …

The Diet Of Oryzomys Palustris Based On Stomach Content Analysis, Shannon L. Wright

Biological Sciences Theses & Dissertations

Oryzomys palustris (Harlan) is unusual in that it is one of two carnivorous mammals in the Family Muridae in North America. A diet analysis of Oryzomys palustris. the marsh rice rat, was done based on stomach contents. This was accomplished by taking the animals from two study areas located on the Eastern Shore of Virginia. The animals were taken monthly for one year. Once caught, the animals were sacrificed and their stomach contents were identified to the lowest taxonomic level possible. This study showed that rice rats were omnivorous mammals, eating a variety of foods, including dicots, monocots, crabs, …

Determinants Of Variation In Avian Mobbing Behavior, Charles Ray Chandler Jr.

Biological Sciences Theses & Dissertations

Using three combinations of two experimental stimuli, I initiated mobbing behavior in various species of birds. The objectives of this research were to test the effects of stimuli on mobbing, the predictions of the hypothesis that mobbing functions to drive a predator away, and the effect of other species and individuals on the mobbing behavior of a bird. Mobbing experiments were conducted in a variety of habitats and locations from January 1983 through February 1984.

Only 6.5% of all trials with the mount-only stimulus were successful in attracting birds. Tape-only and mount-and-tape stimuli were equally effective in attracting birds, but …

Life History Aspects Of Reithrodontomys Humulis In Southeastern Virginia, Michelle Cawthorn Chandler

Biological Sciences Theses & Dissertations

Reithrodontomys humulis, the eastern harvest mouse, is a small cricetid rodent which is common in old field communities in the eastern U.S. A live-trapping study was conducted in Suffolk, Virginia from March 1983 through February 1984 in order to learn the details of its life history and the vegetational characteristics which best describe its microhabitat. Specifically, population densities, trap-revealed survival times, home ranges, plant species composition of the study area, and vegetational structure were examined. In order to trap as many Reithrodontomys as possible, special traps which excluded animals weighing over 20 g were constructed. Densities of harvest mice …

Activity Levels Of Arboreal Rodents Peromysus And Ochrotomys Evaluated With Nest Cans In Seasonally Flooded Forests, John W. Walke

Biological Sciences Theses & Dissertations

The diversity and density of small mammals in the Dismal Swamp are believed to be small. To test this, four 1.96 ha grids were established and operated in the Dismal Swamp National Wildlife Refuge, from September 1981 to November 1982. Number 10 metal cans covered with plastic lids were placed as nest boxes at 0.5 to 1.5 m height on trees. A 2.5 cm hole allowed access by arboreal rodents, to each nest can. The activity level of the two arboreal rodents, Peromyscus leucopus and Ochrotomys nuttalli, was evaluated by observing types of activity ranging from presence of mice to …

Seasonal Feeding Habits Of The River Otter (Lutra Canadensis) In Ditches Of The Great Dismal Swamp, Ronnie M. Pierce

Biological Sciences Theses & Dissertations

To determine the seasonal feeding habits of the river otter (Lutra canadensis) in the Great Dismal Swamp 209 scats were collected, from May 1977 to May 1978, and analyzed for content. Remains of crayfish were found with a frequency of occurrence of 82% while fish remains occurred in 62% of the scat. This is in direct contrast to previous studies (from other areas) which found fish with a greater frequency than crayfish. Fish consumption was believed to increase during periods of low water or low temperatures. Sunfish were represented most frequently and may be the preferred fish. Amphiuma remains …

The Fall And Winter Food Habits Of The Black Bear (Ursus Americanus) In The Great Dismal Swamp Of Virginia, Francis Leonard Daniel

Biological Sciences Theses & Dissertations

A study was conducted on the food habits of the black bear (Ursus americanus) in the Great Dismal Swamp of Virginia. A total of four stomachs and 42 scats were analyzed. Four samples were collected from September and October of 1975, and the remainder of the samples were collected from September 1976 to February 1977. The study was conducted to obtain information vital to the management of this species in the Great Dismal Swamp. Vitis spp. was the primary food item during the fall comprising 43% of the total diet, followed by fruits of Diospyros virginiana and Asimina triloba, each …