Early efforts in wildlife management focused on reducing population variability and maximizing yields of selected species. Later, Aldo Leopold proposed the concept of habitat management as superior to population management, and more recently, ecosystem management, whereby ecological processes are conserved or mimicked, has come into favour. Managing for resilience builds upon these roots, and focuses on maintaining key processes and relationships in social-ecological systems so that they are robust to a great variety of external or internal perturbations at a range of ecological and social scales. Managing for resilience focuses on system-level characteristics and processes, and the endurance of system properties in the face of social or ecological surprise. Managing for resilience consists of actively maintaining a diversity of functions and homeostatic feedbacks, steering systems away from thresholds of potential concern, increasing the ability of the system to maintain structuring processes and feedbacks under a wide range of conditions, and increasing the capacity of a system to cope with change through learning and adaptation. The critical aspect of managing for resilience, and therefore ecosystem management, is undertaking adaptive management to reduce uncertainty and actively managing to avoid thresholds in situations where maintaining resilience is desired. Managing adaptively for resilience is the approach best suited for coping with external shocks and surprises given the non-linear complex dynamics arising from linked social-ecological systems.

Wind energy is of increasing importance for a sustainable energy supply worldwide. At the same time, concerns about the number of birds and bats being killed at wind turbines have been growing. In this situation, methods for a reliable estimation of bird and bat fatality numbers are needed. To obtain an unbiased estimate of the number of fatalities from fatality searches, the probability to detect the carcass of an animal being killed at a turbine has to be assessed by considering carcass persistence rate, searcher efficiency and the probability that a killed animal falls into a searched area. Here, we describe a new formula to determine the detection probability of birds or bats that are killed at wind turbines and which can estimate the number of fatalities from the number of carcasses found. The formula was developed to analyse a large data set of bats killed at wind turbines in Germany. In simulations, we compared it to three other formulas used in this context. Our new formula seems to have unbiased results when searcher efficiency and carcass removal rate are constant over time. When searcher efficiency or carcass removal rate varied with time, all four formulas showed a similar bias. These comparative results can be used to choose between methods depending on the quality of information available. Our estimator can, for instance, be adapted to different situations including temporal changes of searcher efficiency or carcass removal rate because it is based on an explicit process model.

The breeding range of large-bodied waterfowl nesting in the northern boreal forest is likely influenced by breeding season length. This may be particularly true for the largest species of North American waterfowl, the trumpeter swan Cygnus buccinator, due to the extended time period necessary to raise young to fledging. This species recently recovered from near-extinction in the early 1900s to reoccupy historic breeding areas throughout the boreal forest in Alaska, although recolonization patterns may have been influenced by variation in season length over the same time period. This may have resulted in range expansion into areas that were historically unavailable due to an ice-free period insufficient for successful reproduction. We used hierarchical occupancy models to analyze trumpeter swan survey data collected over the entire breeding range in Alaska during 1968-2005. We fit models containing combinations of recolonization parameters, trend and latitude, and season length to these data to determine whether these variables explained the variation in occupancy across our survey area. Support for season length parameters would provide evidence that the recolonization process was partially related to the length of the breeding season. We expected that occupancy probability would increase range-wide due to overall population growth, while occupancy would be greatest at mid-latitudes, near the center of the species range. Because this population was recovering, we also expected that expansion would proceed outward from the range center. Our results indicated that habitat occupancy was positively related to season length, partially explaining the recently observed northward range expansion. Our results suggest that increases in annual temperatures due to climate warming would likely be associated with further range expansion in trumpeter swans and may have implications for other wetland obligates. Changes in species distributions will likely increase competition for breeding areas with potential negative effects on species not limited by season length. This may already be occurring in Alaska where the breeding distribution of trumpeter swans has begun to overlap with that of tundra swans Cygnus columbianus.

During the winter of 2003/04, we studied emigration rates of teal Anas crecca in two major wetlands: the Camargue (southern France) and the Loire estuary (western France). We derived local survival probabilities as a step in ultimately estimating emigration rates from individual mark-resighting (visual recaptures) history of birds fitted with nasal saddles. In goodness-of-fit tests of time-dependent models for local survival, we only detected the presence of transients among young females in the Loire estuary, which indicated that this category of individuals includes an ‘unstable compartment’ continuing its migratory journey further to the south. We observed low monthly local survival and high emigration rates (range: 0.01-0.81) in both areas, which suggests high turnover rates. In the Loire estuary, temporal changes in emigration rates matched the post- and pre-nuptial migration peaks (i.e. October-November and February-March). By combining local survival probabilities and count data, we derived an estimate of the ratio between the winter peak count of teals in our study areas and the minimum number of birds that actually frequented the areas over the entire wintering period (October-March). In both cases, we estimated the number of teal visiting the two wintering sites be about twice as large as the maximum number of birds counted instantaneously.

The high arctic wolf Canis lupus arctos was exterminated from eastern Greenland during the 1930s by commercial hunters and was considered absent for 40 years. In this study, I examined the recolonisation of east Greenland by wolves from north Greenland through an invasion that began in 1979. The invasion successfully led to the establishment of a new population, because a wolf pair arrived into the core historical wolf range followed by one or two wolves during the next four years. Weight of evidence suggested that the invaders arrived into east Greenland through unintentional, human-mediated jump dispersal. I present two cases of long-distance dispersals by lone wolves following military sled patrols in northern Greenland. Wolves had likely failed to establish a viable population in east Greenland for 40 years for the following reasons: 1) a low propagule pressure, 2) invasions were high risk, occurring through vast areas of the lowest, large ungulate prey biomass reported for wolves in North America, and 3) only singletons made it into eastern Greenland.

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.

Effective management of small expanding populations is aided by the availability of reliable estimates of distribution, as well as by demographic characteristics such as population density, genetic diversity and sex ratio. The range of the black bear Ursus americanus in the southeastern United States is expanding to include areas from which it has been extirpated for more than a century. Lack of baseline demographic data in recently reoccupied areas leaves little information on which to base emerging management needs. We estimated the current extent of expansion at the colonizing front of a black bear population in the central Appalachian Mountains and identified landscape-scale habitat characteristics affecting the expansion. In 2007, we genotyped hair samples collected throughout a 8,205-km² area at six microsatellite loci to identify individual black bears and estimate genetic diversity. We used capture-recapture and occupancy analyses to estimate density and distribution of black bears in our study area. Our results suggest that black bears were not uniformly distributed, but were localized to high elevations and protected public conservation lands. Limited availability of high elevations to the west, north and northeast of our study area may limit further expansion. Despite a limited distribution and low estimated population density (7.51 bears/100 km²), genetic diversity at genotyped loci was high (mean H_o = 0.81). Until the population grows further, the small number of individuals in the region may be sensitive to management practices that result in mortalities, especially to females. Our research exemplifies the utility of remote genetic sampling to estimate population demographics of wide-ranging mammals throughout a large study area, particularly where private land ownership hinders intensive study.

We examined interactions related to resource partitioning and competition with density-dependent processes among mule deer Odocoileus hemionus and North American elk Cervus elaphus at two different population densities of elk. We used an experimental approach to examine changes in diet diversity, selection of diets, dietary importance, niche breadth and overlap among sympatric species of large herbivores with changes in population density of one species. We hypothesized that diets of both species would change with changing population density and dietary niche would be expanded to include forages of lower quality in the areas with increased competition for resources. We used microhistological analysis corrected for differential digestibility of forages to estimate diets of mule deer and elk from faeces in two study areas with high and low population densities of elk. For both mule deer and elk, dietary niche was expanded in the high-density area compared with the low-density area, and included forages of lower quality and palatability. Our results indicate that negative feedbacks associated with density-dependent processes interact with competitive interactions among sympatric species of large herbivores.

Aerial surveys using direct counts of animals are commonly used to estimate deer abundance. Forward-looking infrared (FLIR) technology is increasingly replacing traditional methods such as visual observation from helicopters. Our goals were to compare fixed-wing FLIR and visual, helicopter-based counts in terms of relative bias, influence of snow cover and cost. We surveyed five plots: four 41.4 km² plots with free-ranging white-tailed deer Odocoileus virginianus populations in Wisconsin and a 5.3 km² plot with a white-tailed deer population contained by a high fence in Michigan. We surveyed plots using both fixed-wing FLIR and helicopters, both with snow cover and without snow. None of the methods counted more deer than the other when snow was present. Helicopter counts were lower in the absence of snow, but lack of snow cover did not apparently affect FLIR. Group sizes of observed deer were similar regardless of survey method or season. We found that FLIR counts were generally precise (CV = 0.089) when two or three replicate surveys were conducted within a few hours. However, at the plot level, FLIR counts differed greatly between seasons, suggesting that detection rates vary over larger time scales. Fixed-wing FLIR was more costly than visual observers in helicopters and was more restrictive in terms of acceptable survey conditions. Further research is needed to understand what factors influence the detection of deer during FLIR surveys.

Proper management of threatened populations requires prior knowledge of population sizes and structures, however, current techniques to gather this information are generally impractical, costly, and can be physically stressful for the animals. Non-invasive methods (e.g. faecal sampling) that can produce high quality and accurate results are better alternatives. Using faecal samples collected from a Svalbard reindeer Rangifer tarandus platyrhynchus population in the winters of 2008 (N = 158) and 2009 (N = 161), we investigated and validated the feasibility of using faecal pellet sizes to differentiate between female calves, yearlings and adults. We found that pellets from adult females were longer than those from calves, and pellets from adults and yearlings were clearly wider than those from calves. With an accuracy of 91% correct classification, we did show that a combination of faecal pellet dimensions (length, width and depth), rather than a single dimension alone, can allow managers to clearly differentiate between age classes if pellets already identified as being from females are used. We also found a positive relationship between live weight and pellet size of the reindeer. Combined with DNA analysis to identify the gender of the animal that produced the faecal pellet, this information may provide important population parameters and be a valuable tool for the monitoring of various ungulate species including wild reindeer.