Global Positioning System (GPS) telemetry is a prevalent tool now used in the study of large mammals. Global Positioning Systems either store the data on board the collar or contain a remote-transfer ...system that allows for data recovery at more frequent intervals. Spread spectrum (S–S) technology is a new mode of data transfer designed to overcome interference problems associated with narrow-band very high frequency and ultra high frequency data-transfer systems. We evaluated performance of S–S GPS radiocollars deployed on grizzly (Ursus arctos) and black bears (U. americanus). We also evaluated variables that influenced GPS fix success rates, with particular focus on animal activity, time of year, and temperature. The S–S GPS collars performed to our expectations and met study objectives; we did not experience any major problems with the data-transfer system. We observed varying rates of fix success that were directly related to recorded activity counts. Using logistic regression, we verified that activity counts were a reasonable measure of resting or feeding–traveling in both bear species. Our results showed that 73% and 79% of missed fixes, respectively, occurred when we predicted black and grizzly bears to be resting. Temperatures measured in the canister of the collar were not correlated with air temperature, suggesting posture and activity influenced canister temperature. Both measures of temperature were predictive of fix success. We did not find that fix success was related to body morphology (i.e., neck circumference, mass, and chest girth), fix interval, position of the GPS antenna relative to the sky, or sex of the bear. We conclude that fix success for both species is strongly related to activity patterns and time of year. Activity counters appear to be a reasonable measure of this behavior, and we recommend researchers consider including an activity-count system when deploying GPS collars. We also recommend researchers explore building separate models of habitat selection based upon categories of activity to account for bias in fix success associated with bear behavior.
Bear food habits are often quantified using scat analysis, mainly due to its non-invasiveness and because samples are relatively easy to collect. However, lab processing time can be daunting and may ...end up competing with other field activities. Sub-sampling a bear scat to analyze its contents may reduce the lab processing time, but the number of subsamples per scat is usually chosen arbitrarily. We investigated the effect of the number of subsamples per bear scat on the estimatation of the diet composition of the Apennine brown bear in the Abruzzo Lazio and Molise National Park. Based on a sample of 328 bear scats collected in 2006, and from 5 to 1 subsamples (10ml) per scat, dietary analysis showed qualitative and quantitative stability at a decreasing number of subsamples, and only food items of negligible importance were occasionally missed using 1–2 subsamples per scat. We concluded that 2 subsamples can be used without significant loss in accuracy, corresponding to a 60% reduction in lab time, and to more than 50days of lab work for one operator to process our entire bear scat sample. By assessing the effect of sub-sampling a bear scat for dietary analysis, we also present preliminary data on the seasonal food habits of the Apennine brown bear population.
Home range size characterizes the interplay between an organism and its environment. Determinants of home range size can be intrinsic or extrinsic to the individual but all factors relate along a ...hierarchical pattern according to spatial and temporal scale. Determinants of home range size at species and population levels result from relatively slow processes, such as evolutionary changes in body size or global changes in climate. Range determinants at the lower level of individuals, however, can change at a relatively fast rate as they result from more rapid processes, such as the seasonal production of food or annual changes in predation rates. Not only do higher scales constrain those below but also lower level processes combine to affect higher scales. Further, correlates of home range size can differ among scales. To incorporate the possible findings of different patterns at different temporal and spatial scales we recommend using a comparative approach to complement controlled manipulative experiments.
Livestock depredation is an important factor that contributes to low public acceptance of large carnivores, and it is often used as an incentive to reduce large carnivore populations. In central ...Sweden, brown bears Ursus arctos coexist with a traditional cattle husbandry system that allows daytime free-ranging of dairy cattle. Despite a growing brown bear population, depredation on cattle remained stable during the last decade and is among the lowest rates reported worldwide. Nevertheless, major stakeholders argue for a substantial reduction in brown bear numbers, among other reasons, to safeguard the traditional husbandry system. Based on satellite tracking data, we assessed and correlated the resource selection of nine brown bears that were sympatric with six daytime free-ranging cattle herds during the free-ranging season (i.e. June-August) in 2008. We found a significant and negative relationship between resource selection of brown bears and free-ranging cattle during the study period, mainly because of inverse relationships between the species towards vegetation density and human-related infrastructure, such as forest roads, buildings and settlements. We predict that the probability of an encounter between these species, given that there is no directed predation, is highest in dense vegetation patches close to the human habitation-related variables. Because of the low reported depredation rates and the apparent habitat segregation between the species, our results provide no support for the argument to reduce brown bear numbers to safeguard the traditional cattle herding system.
After declining to almost disappearing, the brown bear in
the Pyrenees occupies today two areas, one central area with 23 individuals
and several breeding females, and a western area with only two ...males. The
article describes methods of study and monitoring of the specie, the history
of its Pyrenean population, its census and current distribution, conservation
issues and interactions with human activity, and prospects in the Pyrenees.
Después de disminuir hasta casi desaparecer, el oso pardo en
el Pirineo ocupa hoy dos núcleos: uno central, con 23 individuos y varias hem-
bras reproductoras, y otro occidental, con solo dos machos. Se describen los
métodos de estudio y de seguimiento de la especie, la historia de su población
pirenaica, su censo y distribución actual, los problemas de conservación e
interacciones con la actividad humana, y sus perspectivas en el Pirineo.
The development of wildlife genetics combined with non-invasive sampling might be both an economic benefit for the society and a benefit for the survival of the threatened species. The aims of this ...study are to develop a quality assured approach for DNA profiling of brown bears (
Ursus arctos) in Northern Europe using material from non-invasive sampling and to generate a population database that can be used for conservation management as well as a reference database for forensic purposes. Non-invasive sampling was performed by the collection of scats in the field and by using sets of hair traps in a grid pattern in specified geographical areas. Genotypes from 12 STR loci were determined for 232 Norwegian bears. Initial analysis of the entire sample indicated a high level of substructure. Thus, the sample was divided into four geographically different populations consisting of 206 individuals for further validation of the markers. Ten STRs (G1D, G10L, Mu05, Mu09, Mu10, Mu15, Mu23, Mu50, Mu51, and Mu59) conformed to Hardy–Weinberg equilibrium (HWE) expectations with only minor deviations, while the remaining two STR loci (Mu26 and G10B) were excluded from our set of putative forensic profiling system markers after revealing significant deviations from HWE in all four sub-populations. The average estimate of population substructure for Norwegian bears using 10 STRs (
F
ST) was determined to be 0.1, while the estimate for inbreeding (
F
IS) was −0.02. Accounting for the
F
ST-value, the average probability of identity (PI
ave) was 5.67
×
10
−10 and the average probability of sibling identity (PI
sib) was 1.68
×
10
−4. In Norway, this brown bear DNA profiling system has been applied to forensic casework.
In brown bears (Ursus arctos), nursing of young >1 year of age has a positive effect on their growth rate but is energetically costly for mothers and reduces the number of litters a female can ...produce during her lifetime. We followed radiomarked families to study their behavior during the period of family breakup. Yearlings separated from their mothers during the mating season and most family breakups were associated with the presence of an adult male, suggesting that termination of maternal care was not initiated by offspring.
GPS collars have greatly increased the number of locations obtained for individual animals during telemetry studies, but missed location attempts (missed fixes) may create bias in habitat analyses ...unless appropriately modeled. We placed GPS collars on captive grizzly bears (Ursus arctos) and observed their behavior while the collars attempted to obtain locations. Bear behavior influenced indices of GPS signal attenuation, the angle of the GPS antenna to the horizon, and collar height above the ground, but because bears sometimes rotate their collars, antenna angle varied within a behavior, particularly when collars fit snugly. We used a model selection approach to evaluate the influence of the angle of the GPS antenna to the horizon, collar height above the ground, and bear behavior on fix success. The model with both antenna angle and collar height was most parsimonious. We recommend fitting GPS collars such that the GPS antenna is opposite the battery pack (i.e., oriented up) for greatest fix success. Because collars sometimes rotate, sensors recording the antenna's angle to the horizon and bear height would help researchers model missed fixes related to signal attenuation caused by behavior. Although captive bear behavior may differ from wild bears, we provide a first look at the relative influences of antenna angle, antenna height, and bear behavior. When antenna angle and height information is not available, using activity sensors and bear movement rates to identify resting behavior should be considered to reduce bias in habitat analyses of GPS collar data.
Many temperate zone animals adapt to seasonal changes by altering their physiology. This is mediated in large part by endocrine signals that encode day length and regulate energy balance and ...metabolism. The objectives of this study were to determine if the daily patterns of two important hormones, melatonin and cortisol, varied with day length in captive brown bears (Ursus arctos) under anesthetized and nonanesthetized conditions during the active (March–October) and hibernation periods. Melatonin concentrations varied with time of day and season in nonanesthetized female bears despite exceedingly low nocturnal concentrations (1–4 pg/mL) in the active season. In contrast, melatonin concentrations during hibernation were 7.5‐fold greater than those during the summer in anesthetized male bears. Functional assessment of the pineal gland revealed a slight but significant reduction in melatonin following nocturnal light application during hibernation, but no response to beta‐adrenergic stimulation was detected in either season. Examination of pineal size in two bear species bears combined with a phylogenetically corrected analysis of pineal glands in 47 other species revealed a strong relationship to brain size. However, pineal gland size of both bear species deviated significantly from the expected pattern. Robust daily plasma cortisol rhythms were observed during the active season but not during hibernation. Cortisol was potently suppressed following injection with a synthetic glucocorticoid. The results suggest that melatonin and cortisol both retain their ability to reflect seasonal changes in day length in brown bears. The exceptionally small pineal gland in bears may be the result of direct or indirect selection.
e00048
Plasma melatonin in the brown bear varies with daylength but is present at exceedingly low concentrations. The pineal gland, a major source of melatonin, in the bear is significantly smaller, relative to brain size, than other mammals based on phylogenetic analysis. Cortisol concentrations also varied with daylength.
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