Physiological monitoring of gray wolves (Canis lupus) by radiotelemetry
No abstract available.
Journal of Mammalogy↗
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Dispersal in female white-tailed deer
Seven of 35 yearling female white-tailed deer ( Odocoileus virginianus ) in a migratory herd in northeastern Minnesota dispersed 18–168 km from natal ranges during late May through June. Dispersal as a proximate event appears voluntary and independent of deer density.
Journal of Mammalogy↗
Selection of wolf dens in relation to winter territories in northeastern Minnesota
Locations of wolf ( Canus lupus ) dens in the Superior National Forest in northeastern Minnesota from 1969 through 1988 were analyzed in relation to winter territories. Dens situated within the central 60% of the territories were randomly located relative to territory centers. However, only 10.5% (2) of the dens were located within a 1-km-wide strip inside the territory boundaries, indicating possible avoidance of neighboring packs. A negative relationship ( r 2 = 0.27; P < 0.05) between territory size and den distance from territory center was found, indicating that in large territories wolves might select the denning site that minimizes travel distance from and to the den. Den use was traditional in 86% (6) of the denning alpha females studied for > 1 year, and possibly the availability of a stable food source helped determine den location.
Journal of Mammalogy↗
Buffer zones of territories of gray wolves as regions of intraspecific strife
The locations of 22 territorial gray wolves (Canis lupus) killed by conspecifics in northeastern Minnesota were analyzed in a study involving radio-telemetry from 1968 through 1992. Twenty-three percent of the wolves were killed precisely on the borders of their estimated territories; 41%, within 1.0 km (16% of the radius of their mean-estimated territory) inside or outside the estimated edge; 91%, within 3.2 km inside or outside (50% of the radius of their mean-estimated territory) of the estimated edge. This appears to be the first report of intraspecific mortality of mammals along territorial boundaries.
Journal of Mammalogy↗
Repertoire, structure, and individual variation of vocalizations in the sea otter
Vocalizations of the California sea otter ( Enhydra lutris nereis ) were recorded from wild and captive adults and young and analyzed spectrographically. Parameters measured from the sonagrams included fundamental frequency, duration, maximum frequency, intercall interval, and the location and amplitude of energy peaks. We identified 10 basic vocal categories, one of which consisted of graded signals. The contexts for each call, when known or suspected, are described. Discriminant analysis of the spectrographic parameters for the scream call showed significant differences among individuals for adult females and young. Using only the parameters quantified, each call was assigned correctly to the individual that produced it with 80% accuracy for mothers and 75% for young, thus, indicating that the potential exists for individual vocal recognition in the sea otter. The sea otter's vocal repertoire is similar in complexity to that of certain pinnipeds, but may be less complex than that of several species of social cetaceans and primates. In general, the sea otter's vocal patterns have characteristics thought to be most suitable for short-range communication among familiar individuals.
Journal of Mammalogy↗
Natal dispersal and gene flow in white-tailed deer in northeastern Minnesota
I documented natal dispersal and gene flow in 79 yearling white-tailed deer ( Odocoileus virginianus ) in northeastern Minnesota during 1974–1988. Sixty-four percent ( n = 28) of 44 males and 20% ( n = 7) of 35 females dispersed from their natal home ranges when 1.0–1.5-years old. Eighty-six percent and 95%, of all yearlings including nondispersers, dispersed ≤26 and ≤38 km, respectively. Minimum gene flow was estimated to be 40 deer per generation, based on a circular subpopulation defined by a 26-km radius. Gene flow estimated from allele frequencies for five polymorphic loci averaged 15 deer per generation among five subpopulations. These values of gene flow were concomitant with significant allelefrequency heterogeneity at the subpopulation level.
Journal of Mammalogy↗
Resistance of young wolf pups to inclement weather
Three observations of young wolf ( Canis lupus ) pups in Denali National Park and Preserve, Alaska, and two on Ellesmere Island, Northwest Territories, Canada, indicate that pups <33 days of age are highly resistant to inclement weather, contrary to earlier conjecture.
Journal of Mammalogy↗
Regular and homeward travel speeds of arctic wolves
Single wolves ( Canis lupus arctos ), a pair, and a pack of five habituated to the investigator on an all-terrain vehicle were followed on Ellesmere Island, Northwest Territories, Canada, during summer. Their mean travel speed was measured on barren ground at 8.7 km/h during regular travel and 10.0 km/h when returning to a den.
Journal of Mammalogy↗
Black bears in Arkansas: Characteristics of a successful translocation
In 1958, the Arkansas Game and Fish Commission began translocating black bears ( Ursus americanus ) from Minnesota to the Interior Highlands (Ozark and Ouachita mountains) of Arkansas where bears had been extirpated early in this century. This project continued for 11 years with little public imput, during which time an estimated 254 bears were released. We estimate there are now >2,500 bears in the Interior Highlands of Arkansas, Missouri, and Oklahoma, making it one of the most successful translocations of a Carnivora. Factors that contributed to the success include use of wild-captured animals, elimination of major factors associated with extirpation, release into prime habitats within the former range, multiple release sites, release of 20–40 animals/year for eight years, and release of mostly males prior to release of mostly females. Studies on two allopatric populations demonstrate that they are now diverging in some demographic characteristics, including litter size, cub survivorship, and adult sex-ratio. Translocation of black bears to the Interior Highlands is successful in terms of numbers of animals, but it will not be truly successful until people accept black bears as part of the regional fauna. To that end, those associated with management and research of bears in Arkansas are now focussing on public education and control of nuisance bears.
Arkansas↗
Lack of association between magnetic patterns and the distribution of free-ranging dolphins
While free-ranging dolphins ( Delphinus sp.) have been shown to be associated with bottom topography (depth contours of the sea floor), stranded dolphins have been shown to be associated with magnetic topography. Association with magnetic patterns that may be useful for orientation and navigation by free-ranging dolphins has not been demonstrated. Evaluation of the same 140 locations of free-ranging Delphinus delphis that demonstrate an association with bottom topography patterns shows no association with magnetic intensity gradients or directional orientation with magnetic patterns. Dolphins may be able to detect cues from both bottom topography and magnetic patterns, but the free-ranging dolphins analyzed here are associated with only bottom topography.
Journal of Mammalogy↗
Selection of microsites by grizzly bears to excavate biscuitroots (Lomatium cous)
Roots of the biscuitroot ( Lomatium cous ) are a common food of grizzly bears ( Ursus arctos horribilis ) in drier parts of their southern range. I used random sampling and locations of radiomarked bears in the Yellowstone ecosystem to investigate the importance of mass and starch content of roots, digability of the site, and density of plants relative to selection of sites by grizzly bears to dig biscuitroots. Where biscuitroots were present, most differences between dug and undug sites were related to digability of the site and mass and starch content of roots. Grizzly bears more often dug in sites where average milligrams of starch per kilogram of pull per root (≈energy gain) was high. Density of biscuitroots was not related to selection of sites by grizzly bears. Mass of biscuitroot stems also provided relatively little information about mass of roots. Distribution of biscuitroots was associated with increased cover of rocks and exposure to wind, and with decreased slopes and cover of forbs. Digs by grizzly bears were associated with the presence of biscuitroots, proximity to edge of forest, and increased cover of rocks. Results were consistent with previously observed tendencies of grizzly bears to concentrate their feeding within 50–100 m of cover.
Journal of Mammalogy↗
Timing and synchrony of parturition in Alaska caribou
Timing of parturition of caribou ( Rangifer tarandus ) varies within populations, but the relative influences of nutritional condition of females during the autumn breeding season and during gestation on that variation is not known. We determined timing of parturition of caribou in Denali National Park, Alaska, during 1984–1995, which had wide variation in snowfall that influenced nutritional condition and productivity of females. The first young were observed each year between 4 and 15 May. Annual median dates of parturition for radiocollared females during 1987–1995 varied from 13 to 21 May. Synchrony of births (i.e., proportion of births during 7 days centered on the median date) did not vary significantly among years ( P > 0.05). Females ≤4 years old were more likely to give birth after the annual median date than older females ( P = 0.005). Dates of parturition were significantly correlated with masses of females in the previous autumn ( P = 0.034) but not in late winter ( P = 0.155). Births tended to be earlier for parous females that were not lactating during the previous breeding season compared to those that were lactating ( P = 0.030). Annual onsets of parturition varied significantly with snowfall in late winter prior to conception ( P = 0.012) but not with snowfall during gestation. Timing of parturition in our study appeared to be a function of physical condition of breeding females in autumn.
Journal of Mammalogy↗
Diets of hartebeest and roan antelope in Burkina Faso: Support of the long-faced hypothesis
Diets of hartebeest ( Alcelaphus buselaphus ) and roan antelope ( Hippotragus equinus ) were assessed at the Nazinga Game Ranch in southern Burkina Faso, West Africa. Microhistological analysis of feces indicated that dietary overlap was high during the rainy ( X̄ = 73.7%) and cool-dry (68.2%) seasons, low during the hot-dry season (48.2%), and lowest during the last month of the hot-dry season (31.5%). As the hot-dry season progressed and food presumably became less available, diets of the two antelopes diverged. Hartebeest maintained a high percentage of grass in their diet, but roan antelope switched from being predominantly grazers (>95% grass) to mixed feeders (<50% grass). As grass feeders, both antelopes have skeletal features that facilitate acquisition and grinding of highly fibrous diets, but 11 of 12 mass-relative indices of the skull morphology of hartebeest exceeded those of roan antelope. Because of those differences in skull morphology, and in keeping with the “long-faced” hypothesis, hartebeest were apparently more capable than roan antelope of acquiring and masticating scarce regrowth of perennial grasses when availability of forage was lowest. Such divergence within a single foraging class of African bovids, such as grass feeders, should reduce competition and perpetuate coexistence.
Journal of Mammalogy↗
Population limitation and the wolves of Isle Royale
Population regulation for gray wolves in Isle Royale National Park, Michigan, was examined in 1987-1995 when wolves were in chronic decline following a crash of the population in 1981-1982. Canine parvovirus (CPV-2) was probably influential during the crash, but it disappeared by the late 1980s. High mortality abruptly ceased after 1988, but low recruitment in the absence of disease and obvious shortage of food prevented recovery of the wolf population. In 1983-1995, with a comparable number of moose '10 years old as potential prey, wolves were only half as numerous as in 1959-1980. A simulation of annual fluctuations in effective population size (Ne) for wolves on Isle Royale suggests that their genetic heterozygosity has declined ca. 13% with each generation and ca. 80% in the 50- year history of this population. Inbreeding depression and stochastic demographic variation both remain possible explanations for recent low recruitment.
Michigan↗
Influence of habitat on behavior of Towndsend's ground squirrels (Spermophilus townsendii)
Trade-offs between foraging and predator avoidance may affect an animal's survival and reproduction. These trade-offs may be influenced by differences in vegetative cover, especially if foraging profitability and predation risk differ among habitats. We examined above-ground activity of Townsend's ground squirrels ( Spermophilus townsendii ) in four habitats in the Snake River Birds of Prey National Conservation Area in southwestern Idaho to determine if behavior of ground squirrels varied among habitats, and we assessed factors that might affect perceived predation risk (i.e. predator detectability, predation pressure, population density). The proportion of time spent in vigilance by ground squirrels in winterfat ( Krascheninnikovia lanata ) and mosaic habitats of winterfat-sagebrush ( Artemisia tridentata ) was more than twice that of ground squirrels in burned and unburned sagebrush habitats. We found no evidence for the “many-eyes” hypothesis as an explanation for differences in vigilance among habitats. Instead, environmental heterogeneity, especially vegetation structure, likely influenced activity budgets of ground squirrels. Differences in vigilance may have been caused by differences in predator detectability and refuge availability, because ground squirrels in the winterfat and mosaic habitats also spent more time in upright vigilant postures than ground squirrels in burned-sagebrush or sagebrush habitats. Such postures may enhance predator detection in low-growing winterfat.
Journal of Mammalogy↗
Life-history strategies of ungulates
This Special Feature resulted from a symposium on life-history strategies of ungulates presented at the 78th Annual Meeting of the American Society of Mammalogists in Blacks-burg, Virginia, in June 1998. The presentations at the symposium represented only a vignette of the wide variety of life-history strategies that exists among ungulates. The four papers that follow include treatises on birth-site selection of moose ( Alces alces ), sex-ratio correlates with dimorphism and risk of predation, optimal foraging relative to risk of predation, and the role of density dependence in shaping life-history traits of ungulates. A theme of risk of predation in shaping life-history traits is common to three of four papers.
Journal of Mammalogy↗
Hemoglobin A1c is a retrospective indicator of denning in polar bears (Ursus maritimus)
The nutritional health of polar bears ( Ursus maritimus) is tied to reproductive success, and fasting status can be used to infer recent reproductive history. However, the methods currently used to determine denning and fasting status have their limitations. We examined hemoglobin A1c (HbA1c), an integrative metric of average blood glucose levels over recent months, in free-ranging Southern Beaufort Sea polar bears to assess its usefulness in determining reproductive status and fasting. We compared HbA1c between bears recently in maternity dens that included spring-captured females that were accompanied by cubs-of-the-year ( n = 38), and non-denned bears that included spring-captured females that were accompanied by 1- or 2-yr-old cubs ( n = 39). We predicted that HbA1c would be higher in denned females compared to non-denned females, due to the combined effects of increased circulating glucose associated with insulin resistance from fasting and gestation, as well as the energy mobilization required during early lactation. HbA1c was measured in Polar Bear whole blood samples using an enzymatic assay for quantifying HbA1c and expressed as the percentage of glycated hemoglobin over total hemoglobin. Denned females had higher mean HbA1c ( x̅ 4.70%, 95% CI = 4.54%, 4.86%) than non-denned ( x̅ 4.38%, 95% CI = 4.23%, 4.53%, P = 0.005). We trained a binary logistic regression model to classify the probability of recent prior denning based on HbA1c and glucose, and the model classified denning with 75% accuracy. HbA1c can be used as an effective tool for determining denning history and could have implications for monitoring reproductive success.
Alsaka, Northwest Territories, Yukon↗
A comparison of small-mammal communities in a desert riparian floodplain
We compared small-mammal communities between inactive floodplain and actively flooded terraces of riparian habitat in the Verde Valley of central Arizona. We used species diversity, abundance, weight of adult males, number of juveniles, number of reproductively active individuals, longevity, residency status, and patterns of microhabitat use to compare the two communities. Although abundances of small mammals tended to be higher in the active floodplain, species diversity was greater in the inactive floodplain. Results were inconsistent with our initial prediction that actively flooded riparian habitat acts as a species source, whereas inactive floodplain acts as a sink or dispersal site for small mammals. Within each habitat type, we found evidence of significant microhabitat separation among the three most abundant small-mammal species (Peromyscus boylii, P. eremicus, and Neotoma albigula). Percent cover by annual and perennial grasses and shrubs, substrate, and frequency of shrubs, trees, and debris were significant determinants of small-mammal distribution within a habitat type. We found that the three most abundant species selected a nonrandom subset of available habitat. Nonrandom use of habitat and microhabitat separation were the two most important mechanisms structuring small-mammal communities in riparian habitat of central Arizona.
Journal of Mammalogy↗