Roy Andersen

Risk of capture-related mortality in large free-ranging mammals: experiences from Scandinavia

Abstract Chemical capture and anaesthesia of free-ranging mammals will always involve some risk of mortality even in healthy animals. Deaths may be directly or indirectly attributable to the anaesthetic event itself (e.g. drug overdose, drowning during induction and dart trauma) or may be caused by secondary effects from the capture (e.g. stress, myopathy, trauma or instrumentation with radio-transmitters). In long-term research projects on five major wildlife species in Scandinavia, the capture-related mortality rates (number of captures) were: moose Alces alces 0.7% (N = 2,816), brown bears Ursus arctos 0.9% (N = 1,079), wolverines Gulo gulo 2.8% (N = 461), Eurasian lynx Lynx lynx 3.9% (N = 380), and gray wolves Canis lupus 3.4% (N = 89). We suggest that wildlife professionals should strive for a zero mortality rate but adopt the standard that a mortality rate of > 2% probably should not be accepted in any large mammalian species. This can be achieved by: 1) using an experienced professional capture team, 2) developing and following a capture protocol specific to each species, and 3) requiring that a mortality assessment be undertaken after any capture-related death. This assessment should re-evaluate the capture protocol, including how changes in anaesthetics and methodological approaches could have prevented the mortality.

FAMILY EFFECTS ON GROWTH AND SURVIVAL OF JUVENILE ROE DEER

This paper reports evidence for family effects (i.e., nonindependence between siblings) on components of juvenile fitness in two high-performance populations of roe deer (Capreolus capreolus). In Trois Fontaines (eastern France), 51 sets of twins were ear-tagged as newborns and then intensively monitored until adulthood (to ≥4 yr of age). On the island of Storfosna (central western Norway), 79 sets of twins and 40 sets of triplets were radiotracked from birth to ≥1 mo of age. In both populations, family effects were observed for measures of early body development and winter body mass. Measurements for sibling fawns were more similar than the same measures for nonsiblings. During unfavorable years (i.e., poor deer survival in summer or high population density), sibling fawns survived or died together much more often than expected by chance. Conversely, during favorable years (i.e., high fawn survival or low density), there was no evidence for family effects on survival of either twins or triplets. These re...

Diet shift of a facultative scavenger, the wolverine, following recolonization of wolves

1. Wolves Canis lupus L. recolonized the boreal forests in the southern part of the Scandinavian peninsula during the late 1990s, but so far there has been little attention to its effect on ecosystem functioning. Wolf predation increases the availability of carcasses of large prey, especially moose Alces alces L., which may lead in turn to a diet switch in facultative scavengers such as the wolverine Gulo gulo L. 2. Using 459 wolverine scats collected during winter-spring 2001-04 for DNA identity and dietary contents, we compared diet inside and outside wolf territories while controlling for potential confounding factors, such as prey density. We tested the hypothesis that wolverine diet shifted towards moose in the presence of wolves, while taking into account possible sexual segregation between the sexes. Occurrence of reindeer, moose and small prey was modelled against explanatory covariates using logistic mixed-effects models. Furthermore, we compared diet composition and breadth among habitats and sexes. 3. Occurrence of reindeer, moose and small prey in the diet varied with prey availability and habitat. As expected, diet contained more moose and less reindeer and small prey in the presence of wolves. Their diet in tundra consisted of 40% reindeer Rangifer tarandus L., 39% moose and 9% rodents. In forest with wolf, their diet shifted to 76% moose, 18% reindeer and 5% rodents; compared to 42% moose, 32% reindeer and 15% rodents in forest without wolf. This diet switch could not be explained by higher moose density in wolf territories. Female diet consisted of more small prey than for males, but there was a tendency for females to use the highly available moose carrion opportunistically and to hunt less on small prey within wolf territories. 4. Our study highlights how wolves increase scavenging opportunities for wolverines, and how sexual differences in diet may also apply to large scavengers. Due to their more restricted home range, female wolverines are forced to rely more on hunting small prey. The relatively high occurrence of wolf kills, however, forms an important food source to wolverines in this area. The recolonization of wolves may therefore have contributed to the consequent recolonization of wolverines into the same area.

Reproductive Characteristics of Female Wolverines (Gulo gulo) in Scandinavia

Abstract We studied reproduction of 56 female wolverines (Gulo gulo) in 2 areas of northern Scandinavia. Minimum average age at 1st reproduction was 3.4 years. Mean proportion of females (≥3 years old) reproducing was 0.53 (95% confidence interval [CI] = 0.43–0.63, n = 94), and the annual mean was 0.58 (95% CI = 0.35–0.80, n = 83). Mean annual birth rate was 0.74 (95% CI = 0.33–1.14, n = 83) young per female (≥ 3 years old). Mean size of 74 litters was 1.88 (95% CI = 1.68–2.07, range = 1–4). Examination of our data suggests that female wolverines have low productivity and low capacity to compensate for increased mortality. Therefore, wildlife managers should consider wolverine demographics, especially mortality of adult female wolverines, when developing and implementing conservation policies and harvest regulations.

Impact of infrastructure on habitat selection of wolverines Gulo gulo

Abstract Compared to the other northern large carnivores, wolverines Gulo gulo are thought to be the most sensitive species with regard to habitat changes and human disturbance. Nowadays wolverines in Scandinavia are found in remote high alpine areas, and we investigated whether human development through presence of infrastructure has relegated them to these areas. We analysed wolverine habitat selection and the impact of infrastructure in two study areas in Norway using compositional analysis. We found that alpine tundra with low human development was important for wolverines to locate their home ranges. Human development formed a more important factor for home range location than did habitat, because habitat selectivity was much higher in undeveloped habitats than in developed habitats. Within their home ranges, wolverines used alpine shrubland and forest, irrespective of human development. The sympatric distribution of wolverines with wild and semi-domestic reindeer Rangifer tarandus indicates that wolverines are vulnerable to indirect loss of habitat. However, we hypothesise that wolverine distribution may be partly influenced by direct disturbance or higher risk of human-caused mortality associated with infrastructure. Increased human development and activity in once remote areas may thus cause reduced ability of wolverines to perform their daily activities unimpeded, making the habitat less optimal or causing wolverines to avoid the disturbed area. Our results suggest that the potential exists for further wolverine recovery in forest ecosystems with low levels of infrastructural development.

Social organization and territorial behaviour in a Willow Ptarmigan population

Willow Ptarmigan in Norway showed the same postures and calls as Red Grouse. Territorial behaviour occurred at dusk and dawn from September to December and from April to June. During the day cocks did not defend territories. This daily rythm was apparently acquired rather than genetic, since captive birds did not show it. Whereas Red Grouse at high density display at all times of day, Willow Ptarmigan seldom do so, regardless of density. Cocks showed higher site tenacity than hens. There was no tendency for young cocks to establish territory close to the territory of their parents.

Evaluating scat analysis methods to assess wolverine Gulo gulo diet

Abstract A feeding trial was carried out on two captive wolverines Gulo gulo to evaluate methods to assess wolverine diets through scat content. During the feeding trial, wolverines were offered known quantities of five prey species. All scats were collected and their contents analysed. We evaluated four widely used methods of quantifying dietary composition: dry weight, index of relative contribution, frequency of occurrence, and percentage of occurrence. Based on the outcome of this evaluation, percentage of occurrence was found to be the most appropriate method for wolverine diet studies given the extreme variation in prey items (e.g. prey type and age) and undigested items (e.g. hide and bones) in the wolverines diet. Dry weight may provide additional information on the amount of biomass consumed, which is biologically more meaningful than just the composition assessment derived from using the percentage of occurrence.

Physiologic Evaluation of Medetomidine-Ketamine Anesthesia in Free-ranging Svalbard (Rangifer tarandus platyrhynchus) and Wild Norwegian Reindeer (Rangifer tarandus tarandus)

Abstract Previously published studies indicated that combinations of medetomidine and ketamine were effective for both Svalbard (Rangifer tarandus platyrhynchus) and wild Norwegian reindeer (Rangifer tarandus tarandus). Both previous studies indicated that reindeer were hypoxemic on the basis of pulse oximetry. We conducted a physiologic evaluation of these two protocols using arterial blood gases. Medetomidine (10 mg) and ketamine (200 mg) were administered by dart from the ground in Svalbard reindeer (October 2010) and from a helicopter for wild reindeer (March 2012). Of tested animals, all seven wild reindeer and five of seven Svalbard reindeer were hypoxemic before oxygen administration. Nasal oxygen insufflation (1 L/min for five Svalbard reindeer and one wild reindeer and 2 L/min for four wild reindeer) corrected hypoxemia in all cases evaluated. For reversal, all animals received 5 mg atipamezole per mg medetomidine intramuscularly.