Mean Size Of Home Range Research Articles

Surveillance and movements of Virginia opossum (Didelphis virginiana) in the bovine tuberculosis region of Michigan

Wildlife reservoir hosts of bovine tuberculosis (bTB) include Eurasian badgers (Meles meles) and brushtail possum (Trichosurus vulpecula) in the UK and New Zealand, respectively. Similar species warrant further investigation in the northern lower peninsula of Michigan, USA due to the continued presence of bTB on cattle farms. Most research in Michigan, USA has focused on interactions between white-tailed deer (Odocoileus virginianus) and cattle (Bos taurus) for the transmission of the infectious agent of bTB, Mycobacterium bovis, due to high deer densities and feeding practices. However, limited data are available on medium-sized mammals such as Virginia opossum (Didelphis virginiana; hereafter referred to as opossum) and their movements and home range in Michigan near cattle farms. We conducted surveillance of medium-sized mammals on previously depopulated cattle farms for presence of M. bovis infections and equipped opossum with Global Positioning System (GPS) technology to assess potential differences in home range between farms inside and outside the bTB core area that has had cattle test positive for M. bovis. On farms inside the bTB core area, prevalence in opossum was comparable [6%, 95% confidence interval (CI) 2.0-11.0] to prevalence in raccoon (Procyon lotor; 4%, 95% CI 1.0-9.0, P=0.439) whereas only a single opossum tested positive for M. bovis on farms outside the bTB core area. The prevalence in opossum occupying farms that had cattle test positive for M. bovis was higher (6.4%) than for opossum occupying farms that never had cattle test positive for M. bovis (0.9%, P=0.01). Mean size of home range for 50% and 95% estimates were similar by sex (P=0.791) both inside or outside the bTB core area (P=0.218). Although surveillance efforts and home range were not assessed on the same farms, opossum use of farms near structures was apparent as was selection for farms over surrounding forested habitats. The use of farms, stored feed, and structures by opossum, their ability to serve as vectors of M. bovis, and their propensity to ingest contaminated sources of M. bovis requires additional research in Michigan, USA.

Response of the Mount Graham Red Squirrel (Tamiasciurus hudsonicus grahamensis) to Postfire Conditions

To assess response of Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis) to postfire conditions, we monitored size of home ranges and core areas and characteristics of vegetation at middens in an area of low-intensity burn. For a larger-scale assessment, we monitored mountain-wide occupancy of middens. Although red squirrels selected unburned locations as sites for middens, mean size of home range in a lightly burned area decreased over time, suggesting high availability of resources in lightly burned areas.

Distribution and home range of bottlenose dolphins (Tursiops truncatus) off Veracruz, Mexico

With the goal of gathering ecological data to develop future cetacean management and conservation plans, the distribution, home range, and residency of bottlenose dolphins (Tursiops truncatus) were studied in the central-north Mexican Gulf of Mexico. Between July 2005 and June 2008, 59 boat surveys were carried out for a total of 313 h of effort at sea. During these surveys, 471 individuals were observed in 88 different groups. Photographs of naturally marked animals resulted in 275 different individuals photo-identified. Their distribution was homogeneous throughout the study area at a mean distance from the coast of 2.5 km (SD = 2.9, n = 471) and depths less than 20 m. Of the total of dolphins identified, 202 (73%) had a low sighting rate and were considered transients, whereas 34 individuals (12%) had medium and high sighting rates and were considered resident animals. At the population level, home range estimates calculated using the minimum convex polygon method showed a mean of 2771 ± 1116 km2. Using the adaptive kernel method, the mean size of home range was 1199 ± 143 km2, with five core areas identified. These areas decreased in size during the rainy season because dolphins remained close to the river plumes. At individual level, the mean home range was 129.2 km2 (n = 66), concurring with other reports from the Gulf of Mexico (Texas and Florida) in spite of habitat differences. The main component determining the size of the home range was the presence of rivers, rather than the geomorphology of the coast.

Home Range and Activity of Northern Flying Squirrels (Glaucomys sabrinus) in the Sierra Nevada

Abstract We measured size of home range (adaptive kernel and minimum convex polygon methods), size of nest trees, and distance to nest trees during nightly activity of 13 northern flying squirrels (Glaucomys sabrinus) in two types of forests in Plumas Co., California. We used 95 and 50% adaptive kernel and 95% minimum convex polygon analyses to determine home ranges. Juvenile males had smaller home ranges (6.3 ± 1.6 ha) than adult males (25.5 ± 4.0 ha). There was no significant difference in area of home range by gender or type of forest among adults. Mean size of home range was 29.3 ± 4.5 ha for all adults. Most nests were cavities in live trees and snags, although some external nests were used. Mean distance from locations of northern flying squirrels to the nearest nest tree did not vary throughout the night; however, females tended to travel farther from nest trees.

Availability of Resources and Use of Space in Eastern Chipmunks, Tamias striatus

The adaptive significance of the use of resources is a central issue in population ecology. Empirical and theoretical studies have examined the relationship between mean size of home range and environmental variables. Few studies have examined age, gender, and individual variation in these relationships. We examined the relation between patterns of variation in size of home range in eastern chipmunks, Tamias striatus , and distribution and abundance of resources in northwestern Pennsylvania. Previous research on Tamias showed that mean size of home range responded quickly to changes in abundance of resources, suggesting that individual variation in size of home range would be tied to resources. We captured 278 individuals 3,933 times. Forty individuals were studied in 1981 and 49 in 1982. Home ranges were calculated and all mast-producing trees were mapped yielding expected abundance of resources for all home ranges. Abundance of resources was an increasing function of size of home range even when corrected for competition for access to resources, contrary to predictions based upon models of use of space. When examined by age and sex of chipmunks and by different species of mast-producing trees, we noted that the distribution and abundance of white oaks influenced the distribution of age and sex groups on the study area and appeared to be a disputed resource for adults. Studies of patterns of age, sex, and individual variation in complex behaviors are logistically challenging, but they are the best way to empirically test models in population ecology dealing with the adaptive significance of access to space and resources.

Spatial relationship among individuals of the Japanese lacertid Takydromus tachydromoides (Sauria, Lacertidae)

AbstractThe home range of Takydromus tachydromoides was studied in a grassland area from April 1977 to November 1978. The mean size of home range did not differ markedly between sexes; 136.5 m2 for males and 130.8 m2 for females. Home ranges of adults overlapped greatly in each sex, and the lizard was considered to be non‐territorial. Individuals showed return movement to a definite area (sleeping site) within the home range, and the home range did not shift within a year or between years. Characteristics of the home range of this grassland‐inhabiting lizard were discussed in relation to resource abundance and predation pressure.

A study of the biology of the wild rabbit, Oryctolagus cuniculus (L.), in confined populations. II. The effects of season and population increase on behaviour

The major activities of wild rabbits in confined populations are classified and aefined. Seasonal changes of behaviour are described. The social organization of rabbits in three confined populations during the 1958 breeding season is presented in detail. With increase in density, the number of breeding groups in each population increased, and mean size of group territory and home range decreased. Male home ranges remained larger than female home ranges, and the home ranges of dominant males larger than those of their subordinates except under the most crowded conditions, when all animals in the group moved over the same area irrespective of dominance or sex. Mean size of home range was greatest during the summer months, when social pressures were absent, and smallest during the breeding season, when social activities were at a maximum. During the breeding season the dominant and older animals moved over larger areas than their younger subordinates, and males moved over larger areas than females. During the summer most of these differences disappeared. Aggression between males was always high. With increase in population, aggression against foreign males increased. Aggression between females was low at low densities. As the population grew, aggression between the females belonging to the same group increased. Most shifts of home range occurred during the period of group formation, when young adults of both sexes were forced to move to join breeding groups, and towards the end of the breeding season when the older young began competing sexually with their parents. Shifts of young rabbits during the breeding season were also common, but many of these were probably due to experimental scattering of kittens. The formation of breeding groups was initiated by the behaviour of old females with previous breeding histories.