Habitat selection of resident and non-resident gray wolves: implications for habitat connectivity.

Habitat selection studies facilitate assessing and predicting species distributions and habitat connectivity, but habitat selection can vary temporally and among individuals, which is often ignored. We used GPS telemetry data from 96 Gray wolves (Canis lupus) in the western Great Lakes region of the USA to assess differences in habitat selection while wolves exhibited resident (territorial) or non-resident (dispersing or floating) movements and discuss implications for habitat connectivity. We used a step-selection function (SSF) to assess habitat selection by wolves exhibiting resident or non-resident movements, and modeled circuit connectivity throughout the western Great Lakes region. Wolves selected for natural land cover and against areas with high road densities, with no differences in selection among wolves when resident, dispersing, or floating. Similar habitat selection between resident and non-resident wolves may be due to similarity in environmental conditions, when non-resident movements occur largely within established wolf range rather than near the periphery or beyond the species range. Alternatively, non-resident wolves may travel through occupied territories because higher food availability or lower human disturbance outweighs risks posed by conspecifics. Finally, an absence of differences in habitat selection between resident and non-resident wolf movements may be due to other unknown reasons. We recommend considering context-dependency when evaluating differences in movements and habitat use between resident and non-resident individuals. Our results also provide independent validation of a previous species distribution model and connectivity analysis suggesting most potential wolf habitat in the western Great Lakes region is occupied, with limited connectivity to unoccupied habitat.

Distribution model transferability for a wide-ranging species, the Gray Wolf.

Using existing data can be a reliable and cost-effective way to predict species distributions, and particularly useful for recovering or expanding species. We developed a current gray wolf (Canis lupus) distribution model for the western Great Lakes region, USA, and evaluated the spatial transferability of single-state models to the region. This study is the first assessment of transferability in a wide-ranging carnivore, as well as one of few developed for large spatial extents. We collected 3500 wolf locations from winter surveys in Minnesota (2017-2019), Wisconsin (2019-2020), and Michigan (2017-2020). We included 10 variables: proportion of natural cover, pastures, and crops; distance to natural cover, agriculture, developed land, and water; major and minor road density; and snowfall (1-km res.). We created a regional ensemble distribution by weight-averaging eight models based on their performance. We also developed single-state models, and estimated spatial transferability using two approaches: state cross-validation and extrapolation. We assessed performance by quantifying correlations, receiver operating characteristic curves (ROC), sensitivities, and two niche similarity indices. The regional area estimated to be most suitable for wolves during winter (threshold = maximum sensitivity/specificity) was 106,465 km2 (MN = 48,083 km2, WI = 27,757 km2, MI = 30,625 km2) and correctly predicted 88% of wolf locations analyzed. Increasing natural cover and distance to crops were consistently important for determining regional and single-state wolf distribution. Extrapolation (vs. cross-validation) produced results with the greatest performance metrics, and were most similar to the regional model, yet good internal performance was unrelated to greater extrapolation performance. Factors influencing species distributions are scale-dependent and can vary across areas due to behavioral plasticity. When extending inferences beyond the current occurrence of individuals, assessing variation in ecology such as habitat selection, as well as methodological factors including model performance, will be critical to avoid poor scientific interpretations and develop effective conservation applications. In particular, accurate distribution models for recovering or recovered carnivores can be used to develop plans for habitat management, quantify potential of unoccupied habitat, assess connectivity modeling, and mitigate conflict, facilitating long-term species persistence.

Variable intraspecific space use supports optimality in an apex predator.

Within optimality theory, an animal's home range can be considered a fitness-driven attempt to obtain resources for survival and reproduction while minimizing costs. We assessed whether brown bears (Ursus arctos) in two island populations maximized resource patches within home ranges (Resource Dispersion Hypothesis [RDH]) or occupied only areas necessary to meet their biological requirements (Temporal Resource Variability Hypothesis [TRVH]) at annual and seasonal scales. We further examined how intrinsic factors (age, reproductive status) affected optimal choices. We found dynamic patterns of space use between populations, with support for RDH and TRVH at both scales. The RDH was likely supported seasonally as a result of bears maximizing space use to obtain a mix of nutritional resources for weight gain. Annually, support for RDH likely reflected changing abundances and distributions of foods within different timber stand classes. TRVH was supported at both scales, with bears minimizing space use when food resources were temporally concentrated. Range sizes and optimal strategies varied among sex and reproductive classes, with males occupying larger ranges, supporting mate seeking behavior and increased metabolic demands of larger body sizes. This work emphasizes the importance of scale when examining animal movement ecology, as optimal behavioral decisions are scale dependent.

Mortality of a large wide-ranging mammal largely caused by anthropogenic activities.

With efforts to restore large mammal populations following extirpations, it is vital to quantify how they are impacted by human activities and gain insights into population dynamics in relation to conservation goals. Our objective was to characterize cause-specific mortality of black bears (Ursus americanus) throughout their range. We first quantified cause-specific mortality for 247 black bears in one harvested and two non-harvested populations. We then simulated a small recolonizing population with and without anthropogenic mortality. Lastly, we conducted a meta-analysis of all published black bear mortality studies throughout North America (31 studies of 2630 bears). We found anthropogenic mortality was greater than natural mortality, non-harvest anthropogenic mortality (e.g. poaching, defense of property, etc.) was greater in non-harvested populations, and harvesting was one of the major causes of mortality for bears throughout their range. Our simulation indicated that removing anthropogenic mortality increased population size by an average of 23% in 15 years. We demonstrated that bears are exposed to high levels of anthropogenic mortality, and the potential for human activities to slow population growth in expanding populations. Management and conservation of wide-ranging mammals will depend on holistic strategies that integrate ecological factors with socio-economic issues to achieve successful conservation and coexistence.

Alpha-chloralose immobilization of rock doves in Ohio.

To improve capture efficacy of rock doves (Columba livia) in nuisance situations, we reevaluated the effectiveness of three dosages (60, 120 and 180 mg/kg) of alpha-chloralose (AC). Responses to immobilization using 180 mg/kg AC also were compared in rock doves deprived of food for 16 hr and not food deprived. Mean (+/- SE) time to first effects (33 +/- 2 min) and mean time to capture (94 +/- 5 min) were significantly less for rock doves receiving 180 mg/kg than for rock doves receiving lower dosages (> or = 53 +/- 3 min and > or = 153 +/- 17 min, respectively). Ten, 10, and eight rock doves immobilized with 60, 120, and 180 mg/kg AC recovered within 24 hr, respectively; all rock doves recovered within 29 hr. Although food-deprived rock doves showed effects of AC immobilization earlier than did rock doves with food, time to capture was similar between these two groups. For capturing rock doves, we recommend treating corn with 3 mg AC/kernel and using 180 mg/kg as the effective dose. This modified formulation and dosage should improve capture success of rock doves substantially and improve the ability to resolve nuisance rock dove problems.

Comparison of three formulations of alpha-chloralose for immobilization of Canada geese.

The effectiveness of an alpha-chloralose (AC)-corn oil suspension, an AC-margarine mixture, and AC tablets were compared for immobilizing Canada geese (Branta canadensis). Responses to AC immobilization also were compared in male and female Canada geese. There was no difference in mean time to first effects or mean time to capture between male and female geese dosed with 30 mg/kg AC in orally-administered bread baits. Recovery times (< or = 24 hr) also were similar between sexes. Mean (+/-SE) time to first effects for geese immobilized with AC tablets in bread baits (19 +/- 3 min) was significantly less than mean time to first effects for geese immobilized with AC in margarine (28 +/- 6 min) or AC in corn oil (32 +/- 7 min) applied to bread baits (n = 12 geese/treatment). Respective mean times to capture geese immobilized with AC tablets, AC-margarine, and AC-corn oil were not significantly different at 62 +/- 25, 89 +/- 48, and 88 +/- 30 min, respectively. Ten, 11 and, seven geese immobilized with AC tablets, AC-margarine, and AC-corn oil recovered within 24 hr, respectively; all geese recovered within 28 hr. Male and female Canada geese respond similarly to AC immobilization, at least during molt, and AC mixed with margarine or AC in tablet form is at least as effective as the presently used AC-corn oil suspension. AC tablets or AC-margarine also would be more practical for some field situations. Additional development of AC tablets will be required prior to field use for capturing nuisance waterfowl.

Immobilization of muskrats (Ondatra zibethicus) with ketamine and xylazine.

The effectiveness of ketamine and xylazine as an immobilizing combination for muskrats (Ondatra zibethicus) was evaluated. Eleven muskrats were intramuscularly injected using a high (n = 7) or low (n = 4) dosage of a 20:1 mixture of ketamine (12 or 20 mg) and xylazine (0.6 or 1.0 mg) in Carlton County, Minnesota (USA) from 1 to 4 May 1995. Mean (+/- SD) induction times for muskrats receiving a high dosage (6.5 +/- 2.6 min) or low dosage (7.0 +/- 1.6 min) was similar (P = 0.71). In contrast, muskrats receiving a low dosage recovered sooner (37.0 +/- 15.1 min) than muskrats receiving a high dosage (62.2 +/- 15.6 min) (P = 0.04). There was a positive linear relationship (r2 = 0.75, P = 0.02) between the amount (mg/kg) of ketamine-xylazine injected and recovery time but not between the amount injected and induction time (r2 = 0.49, P = 0.18). Heart rate, respiratory rate, and body temperature were similar (P = 0.20 to 0.62) between high and low dose groups. No mortality occurred nor were short-term adverse effects observed in recaptured individuals. I conclude that a 20:1 mixture of ketamine-xylazine is a safe and effective immobilization agent for muskrats when conducting non-surgical field procedures. Immobilizing muskrats with 15 mg/kg ketamine and 0.75 mg/kg xylazine should provide about 10 min of handling time before arousal and allow full recovery in < 60 min.

Isoflurane as an inhalation anesthetic for muskrats (Ondatra zibethicus).

The effectiveness of isoflurane as an inhalation anesthetic for muskrats (Ondatra zibethicus) was evaluated. Thirty muskrats were anesthetized in an enclosed chamber using 10 ml of isoflurane in Carlton County, Minnesota (USA), from 27 September to 24 October 1994. Mean (+/- SE) induction time for adults, juveniles, and kits was 20.6 +/- 2.9, 21.5 +/- 2.4, and 16.9 +/- 5.3 min, respectively (P = 0.77). Respective mean arousal times for adults, juveniles, and kits were 5.1 +/- 0.5, 5.7 +/- 0.7, and 5.7 +/- 0.6 min (P = 0.78). Heart rate, respiration rate, and body temperature were similar among age classes (P = 0.08 to 0.58). Mortality (3.3%) was comparable to that of other inhalation anesthetics. No short-term adverse effects were observed in recaptured individuals. Isoflurane is a safe and effective inhalation anesthetic for muskrats, although prolonged induction may limit its use in field studies.

Field immobilization of American martens (Martes americana) and short-tailed weasels (Mustela erminea).

Ketamine hydrochloride (KH) and a 5:1 combination of KH and xylazine hydrochloride (XH) were used successfully to immobilize short-tailed weasels (Mustela erminea) and American martens (Martes americana), respectively. Four adult male martens were intramuscularly injected with 30 to 82 mg/kg KH and 8.0 to 16.4 mg/kg XH. Three adult male short-tailed weasels were intramuscularly injected with 20.8 to 42.1 mg/kg KH. Mean (+/- SE) induction times for martens and short-tailed weasels were 1.8 +/- 0.2 min and 46 +/- 4.1 sec, respectively; recovery times were 100.4 +/- 19.3 min and 97.9 +/- 6.3 min, respectively. Heart rate was relatively constant among martens; however, respiration varied widely (21 to 122 breaths per minute). Marten body temperature decreased between 0 and 20 min post-recumbency. Short-tailed weasel heart rate and respiration decreased in response to sedation until slightly before arousal. Body temperature stabilized by 20 min post-recumbency. Two short-tailed weasels tremored slightly within 10 min of arousal. I conclude that KH and KH/XH are safe immobilizing agents for martens and short-tailed weasels, respectively.

Immobilization of fishers (Martes pennanti) with ketamine hydrochloride and xylazine hydrochloride.

A combination of 100 mg ketamine hydrochloride (KH) and 20 mg xylazine hydrochloride (XH) was used to immobilize fishers (Martes pennanti). Four adult males were intramuscularly injected a total of five times at dosages between 22.4 to 29.0 mg/kg KH and 4.1 to 6.6 mg/kg XH. Mean (+/- SE) induction time and arousal time were 3.3 +/- 0.5 min and 76.8 +/- 12.1 min, respectively. Respiration, heart rate, and body temperature in response to sedation appeared normal. A 5:1 mixture of KH-XH appears to be a safe immobilizing agent for fishers.