Comparing the Efficacy of Two Immobilization Drug Combinations for the Chemical Restraint of Bobcats (Lynx rufus)

Chemical immobilization agents that provide rapid induction time, short duration of action, wide margin of safety, and postreversal recovery are important attributes to the handling process of immobilized animals. We evaluated differences in induction, recovery, and physiologic parameters in 23 (13 female, nine adults and four yearlings; 10 male, nine adults and one yearling) free-ranging bobcats (Lynx rufus) chemically immobilized with an intramuscular combination of ketamine (10 mg/kg) and xylazine (KX; 1.5 mg/kg; n=11) or a combination of butorphanol (0.8 mg/kg), azaperone (0.27 mg/kg), and medetomidine (BAM; 0.32 mg/kg; n=12). Induction parameters, time to first effect, hemoglobin oxygen saturation, and anesthesia between bobcats administered KX and BAM were similar. Pulse rate was significantly higher for KX than for BAM. Time to standing and full recovery after reversal were faster for bobcats administered BAM than KX. Six of 11 (55%) bobcats given KX were effectively immobilized with a single injection, and five required additional drugs to allow adequate time for processing. Of 12 bobcats given BAM, six (50%) were effectively immobilized with a single injection, three (25%) individuals were not completely immobilized and required additional doses to allow adequate time for processing, and three (25%) required additional doses after complete arousal during processing. We found that BAM provided reduced sedation and processing times (<30 min), whereas KX provided extended sedation and processing times beyond 30 min. We suggest that researchers increase initial BAM drug volumes for yearling and adult bobcats at time of processing and consider taking appropriate safety precautions when handling free-ranging bobcats.

Density and activity patterns of bobcat in its southernmost distribution

Estimating density and activity patterns is useful for management and conservation of species. Data for Mexican bobcat (Lynx rufus) populations are scarce. Here we estimated the density of a bobcat population in Oaxaca, southern Mexico, and evaluated its daily activity patterns. We also evaluated macroecological patterns of bobcat density across its distribution range to determine any geographical (latitudinal, longitudinal, elevation, or range centroid) or climatic effects on the population density. Camera–trap data were divided into four 60–day periods (two in the dry season and two in the rainy season). Density was calculated using the random encounter model and daily activity patterns were analyzed fitting a kernel density function. The mean estimated density for the four periods was 17.3 bobcats/100 km2, with the highest densities occurring during the dry periods. Bobcat daily activity pattern presented two peaks, one after midnight and the other after dawn, with very slight changes between seasons. In the study area, density and activity patterns were associated with anthropogenic perturbation and prey availability. Bobcats increased their population density in the dry season, and showed a preference for activity at night and early morning hours when it is cooler and there are likely fewer competitors but more prey. Across its range, bobcat density was mainly related to annual precipitation and mean temperature of the driest quarter at 100 km radius buffers, and between annual precipitation and longitude on a smaller scale (50 km radius buffers). These findings support their preference for the arid or mesic environments that enabled them to reach southern areas of the Neartic region.

Beating the heat: ecology of desert bobcats

Background

Relative to temperate regions, little is known about bobcats (Lynx rufus) in the Sonoran Desert portion of their range, in part due to the difficulty of sampling an elusive carnivore in harsh desert environments. Here, we quantify habitat selection and evaluate diet of bobcats at Kofa National Wildlife Refuge, Arizona, USA, using multiple sampling techniques including GPS telemetry, camera traps, and DNA metabarcoding.

Results

Home ranges during the hot season were smaller than during the cool season. Camera trapping failed to yield a high enough detection rate to identify habitat occupancy trends but third-order resource selection from GPS-collar data showed a preference for higher elevations and rugged terrain at lower elevations. Diet composition consisted of a diverse range of available small prey items, including a higher frequency of avian prey than previously observed in bobcats.

Conclusions

Desert bobcats in our study maintained smaller home ranges and primarily consumed smaller prey than their more northern relatives. This study illustrates the benefit of employing multiple, complementary sampling methods to understand the ecology of elusive species.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12862-022-01973-3.

Multiscale patterns of isolation by ecology and fine-scale population structure in Texas bobcats

Patterns of spatial genetic variation can be generated by a variety of ecological processes, including individual preferences based on habitat. These ecological processes act at multiple spatial and temporal scales, generating scale-dependent effects on gene flow. In this study, we focused on bobcats (Lynx rufus), a highly mobile, generalist felid that exhibits ecological and behavioral plasticity, high abundance, and broad connectivity across much of their range. However, bobcats also show genetic differentiation along habitat breaks, a pattern typically observed in cases of isolation-by-ecology (IBE). The IBE observed in bobcats is hypothesized to occur due to habitat-biased dispersal, but it is unknown if this occurs at other habitat breaks across their range or at what spatial scale IBE becomes most apparent. Thus, we used a multiscale approach to examine isolation by ecology (IBE) patterns in bobcats (Lynx rufus) at both fine and broad spatial scales in western Texas. We genotyped 102 individuals at nine microsatellite loci and used partial redundancy analysis (pRDA) to test if a suite of landscape variables influenced genetic variation in bobcats. Bobcats exhibited a latitudinal cline in population structure with a spatial signature of male-biased dispersal, and no clear barriers to gene flow. Our pRDA tests revealed high genetic similarity in similar habitats, and results differed by spatial scale. At the fine spatial scale, herbaceous rangeland was an important influence on gene flow whereas mixed rangeland and agriculture were significant at the broad spatial scale. Taken together, our results suggests that complex interactions between spatial-use behavior and landscape heterogeneity can create non-random gene flow in highly mobile species like bobcats. Furthermore, our results add to the growing body of data highlighting the importance of multiscale study designs when assessing spatial genetic structure.

Sex-specific effects of reproductive season on bobcat space use, movement, and resource selection in the Appalachian Mountains of Virginia

Across taxa, sex-specific demands vary temporally in accordance with reproductive investments. In solitary carnivores, females must provision and protect young independently while meeting increased energetic demands. Males seek to monopolize access to females by maintaining large territories and defending them from other males. For many species, it is poorly understood how these demands relate to broad-scale animal movements. To investigate predictions surrounding the reproductive strategies of solitary carnivores and effects of local conditions on bobcat (Lynx rufus) spatial ecology, we examined the effects of sex and reproductive season on home range size, movement rate, and resource selection of bobcats in the central Appalachian Mountains. Male seasonal home ranges were approximately 3 times larger than those of females (33.9 ± 2.6 vs. 12.1 ± 2.4 km2, x±SE), and male movement rates were 1.4 times greater than females (212.6 ± 3.6 vs. 155 ± 8.2 m/hr), likely reflecting male efforts to maximize access to females. Both sexes appear to maintain relatively stable seasonal home ranges despite temporally varying reproductive investments, instead adjusting movements within home ranges. Males increased movements during the dispersal period, potentially reflecting increased territoriality prior to breeding. Females increased movements during the kitten-rearing period, when foraging more intensively, and frequently returning to den sites. Both sexes selected home ranges at higher elevations. However, females selected deciduous forest and avoided fields, whereas males selected fields and avoided deciduous forest, perhaps explained by male pressure to access multiple females across several mountain ridges and higher risk tolerance. Seasonal changes in home range selection likely reflect changes in home range shape. Increased female avoidance of fields during kitten rearing may indicate female avoidance of presumably resource rich, yet risky, fields at the time when kittens are most vulnerable. Our results indicate that while reproductive chronology influences the spatial ecology of solitary carnivores, effects may be constrained by territoriality.

Space Use and Movement of Urban Bobcats

Global urbanization is rapidly changing the landscape for wildlife species that must learn to persist in declining wild spacing, adapt, or risk extinction. Many mesopredators have successfully exploited urban niches, and research on these species in an urban setting offers insights into the traits that facilitate their success. In this study, we examined space use and activity patterns from GPS-collared bobcats (Lynx rufus) in the Dallas-Fort Worth metroplex, Texas, USA. We found that bobcats select for natural/agricultural features, creeks, and water ways and there is greater home-range overlap in these habitats. They avoid roads and are less likely to have home-range overlap in habitats with more roads. Home-range size is relatively small and overlap relatively high, with older animals showing both greater home-range size and overlap. Simultaneous locations suggest bobcats are neither avoiding nor attracted to one another, despite the high overlap across home ranges. Finally, bobcats are active at all times of day and night. These results suggest that access to natural features and behavioral plasticity may enable bobcats to live in highly developed landscapes.

A winter energetics model for bobcats in a deep snow environment

Understanding basic energetic requirements of wildlife species is critical to evaluate how individuals persist in their current environments as well as to forecast responses to changed climates or habitats. Indeed, northern range limits are often thought to reflect harsh abiotic conditions that exceed the capacity of individuals to stay in energetic balance. Bobcats (Lynx rufus) occur across much of North America; at northern latitudes, they face winter challenges such as deep snows, cold temperatures, and possible food scarcity. We developed an energetics model from field data on movements, body mass, and observed diet of bobcats in mountains of northwest Montana, then evaluated overwinter prey requirements that would enable bobcats to stay in energy balance in this difficult environment. Our model indicated average daily energy expenditures were ~ 1.41× basal metabolic rate. For 90 days from December to February, a 10.5 kg bobcat consuming prey items in proportion with the observed diet for bobcats in this area would need about 2.1 kg of deer (Odocoileus spp.), 7 snowshoe hares (Lepus americanus), 155 red squirrels (Tamiasciurus hudsonicus), 9 woodrats (Neotoma cinerea), and 250 small rodents (Cricetidae). Bobcats have considerable flexibility in diet, movements, and both timing and duration of daily activity to adjust their energetic expenditures in winter.