| 1. |
- Rhodes, J R, et al.
(författare)
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Optimizing Presence–Absence Surveys For Detecting Population Trends
- 2006
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Ingår i: Journal of Wildlife Management. - 0022-541X. ; 70:1, s. 8-18
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Tidskriftsartikel (refereegranskat)abstract
- Presence–absence surveys are a commonly used method for monitoring broad-scale changes in wildlife distributions. However, the lack of power of these surveys for detecting population trends is problematic for their application in wildlife management. Options for improving power include increasing the sampling effort or arbitrarily relaxing the type I error rate. We present an alternative, whereby targeted sampling of particular habitats in the landscape using information from a habitat model increases power. The advantage of this approach is that it does not require a trade-off with either cost or the Pr{type I error} to achieve greater power. We use a demographic model of koala (Phascolarctos cinereus) population dynamics and simulations of the monitoring process to estimate the power to detect a trend in occupancy for a range of strategies, thereby demonstrating that targeting particular habitat qualities can improve power substantially. If the objective is to detect a decline in occupancy, the optimal strategy is to sample high-quality habitats. Alternatively, if the objective is to detect an increase in occupancy, the optimal strategy is to sample intermediate-quality habitats. The strategies with the highest power remained the same under a range of parameter assumptions, although observation error had a strong influence on the optimal strategy. Our approach specifically applies to monitoring for detecting long-term trends in occupancy or abundance. This is a common and important monitoring objective for wildlife managers, and we provide guidelines for more effectively achieving it.
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| 2. |
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| 3. |
- Cederlund, Göran, et al.
(författare)
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Summer movements of female moose and dispersal of their offspring
- 1987
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Ingår i: Journal of Wildlife Management. - : John Wiley & Sons. - 0022-541X .- 1937-2817. ; 51:2, s. 342-352
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Tidskriftsartikel (refereegranskat)abstract
- Fifty-seven radio-equipped moose (Alces alces) in central Sweden were located during the 3 summers of 1980-83. Forty-two were cows (≤2 years old) and 15 were calves (5 males and 10 females) when captured. Aerial tracking was conducted ≤1 time/week. No significant differences in average size of summer home ranges were found between age classes. All cows returned to the same summer range each spring. Consecutive summer home ranges overlapped from 1 to 100%. Ten of 14 radio-equipped calves accompanied their cow to summer ranges. The 1st indications of separation between cow and offspring were recorded from 7 to 29 May. The average straight line distance between cow and offspring successively increased from separation to mid-June when it became relatively constant (1.5-2.0 km). One of 10 calves that completed the migration together with the cow abandoned its mother's home range completely. Adult female offspring continued to reside near their yearling home range during consecutive summers.
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| 4. |
- Charlier, Johan, et al.
(författare)
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Genetic structure and evidence of a local bottleneck in moose in Sweden
- 2008
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Ingår i: Journal of Wildlife Management. - : Wiley. - 0022-541X .- 1937-2817. ; 72:2, s. 411-415
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Tidskriftsartikel (refereegranskat)abstract
- The moose (Alces alces) is the most intensely managed game species in Sweden. Despite the biological and socioeconomical importance of moose, little is known of its population genetic structure. We analyzed 132 individuals from 4 geographically separate regions in Sweden for genetic variability at 6 microsatellite loci. We found evidence of strong substructuring and restricted levels of gene flow in this potentially mobile mammal. FST values were around 10%, and assignment tests indicated 3 genetically distinct populations over the study area. Spatial autocorrelation analysis provided a genetic patch size of approximately 420 km, implying that moose less than this distance apart are genetically more similar than 2 random individuals. Allele and genotype frequency distributions suggested a recent bottleneck in southern Sweden. Results indicate that moose may be more genetically divergent than currently anticipated, and therefore, the strong hunting pressure that is maintained over all of Sweden may have considerable local effects on genetic diversity. Sustainable moose hunting requires identification of spatial genetic structure to ensure that separate, genetically distinct subpopulations are not overharvested.
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| 5. |
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| 6. |
- Hofmeester, Tim
(författare)
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Inter-population variability in movement parameters: practical implications for population density estimation
- 2023
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Ingår i: Journal of Wildlife Management. - 0022-541X. ; 87
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Tidskriftsartikel (refereegranskat)abstract
- Motion-sensitive cameras are popular as non-invasive monitoring tools, and several methods have been developed to estimate population densities from camera data. These methods frequently rely on auxiliary movement data including the distance traveled by an individual in a day and the proportion of the day that an animal spends moving when individual recognition is not possible. The estimation of these movement parameters is time-consuming, which could limit the applicability of cameras to estimate population density. To investigate the relevance of measuring movement parameters for the target population, we monitored 54 wildlife populations of red deer (Cervus elaphus), fallow deer (Dama dama), roe deer (Capreolus capreolus), wild boar (Sus scrofa), and red fox (Vulpes vulpes) in different seasons through Europe with cameras. We estimated 91-day ranges and activity levels. We fitted mixed models for day range and activity level as response variables to assess if the inter-population variability in movement was explained by a set of a priori relevant geographical, environmental, biological, and management predictors. We then explored the bias in density estimates obtained in 25 independent populations when using predicted movement data. There was high intra-species variation in day range and activity level among species and populations. Only species explained a small proportion of this variability; other predictor variables did not. We observed bias in densities when predicting the day range and activity for independent populations. Considering the intra-species variability in movement parameters and the consequent unacceptable bias in density estimates, we recommend that monitoring and conservation programs estimate movement parameters for the target population and survey populations from camera data for more accurate density estimates. While this increases the handling time needed to estimate densities, it is worth the cost because of the reliability of camera-based methodologies to estimate needed movement parameters.
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| 7. |
- Inman, Robert Michael
(författare)
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Recovery of Wolverines in the Western United States: Recent Extirpation and Recolonization or Range Retraction and Expansion?
- 2014
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Ingår i: Journal of Wildlife Management. - : Wiley. - 0022-541X. ; 78, s. 325-334
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Tidskriftsartikel (refereegranskat)abstract
- Wolverines were greatly reduced in number and possibly extirpated from the contiguous United States (U.S.) by the early 1900s. Wolverines currently occupy much of their historical range in Washington, Idaho, Montana, and Wyoming, but are absent from Utah and only single individuals are known to occur in California and Colorado. In response, the translocation of wolverines to California and Colorado is being considered. If wolverines are to be reintroduced, managers must identify appropriate source populations based on the genetic affinities of historical and modern wolverine populations. We amplified the mitochondrial control region of 13 museum specimens dating from the late 1800s to early 1900s and 209 wolverines from modern populations in the contiguous U.S. and Canada and combined results with previously published haplotypes. Collectively, these data indicated that historical wolverine populations in the contiguous U.S. were extirpated by the early 20th century, and that modern populations in the contiguous U.S. are likely the descendants of recent immigrants from the north. The Cali1 haplotype previously identified in California museum specimens was also common in historical samples from the southern Rocky Mountains, and likely evolved in isolation in the southern ice-free refugium that encompassed most of the contiguous U.S. during the last glaciation. However, when southern populations were extirpated, these matrilines were eliminated. Several of the other haplotypes found in historical specimens from the contiguous U.S. also occur in modern North American populations, and belong to a group of haplotypes that are associated with the rapid expansion of northern wolverine populations after the last glacial retreat. Modern wolverines in the contiguous U.S. are primarily haplotype A, which is the most common and widespread haplotype in Canada and Alaska. For the translocation of wolverines to California, Colorado, and other areas in the western U.S., potential source populations in the Canadian Rocky Mountains may provide the best mix of genetic diversity and appropriate learned behavior. (c) 2014 The Wildlife Society.
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| 8. |
- Kenward, Robert, et al.
(författare)
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Rapid sustainability modeling for raptors by radiotagging and DNA-fingerprinting
- 2007
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Ingår i: Journal of Wildlife Management. - : Wiley. - 0022-541X .- 1937-2817. ; 71:1, s. 238-245
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Tidskriftsartikel (refereegranskat)abstract
- Sustainable use of wildlife is crucial to ensuring persistence of natural resources. We used age-specific survival and breeding data to parameterize a demographic model for a harvested Kazakh saker falcon (Falco cberrug) population by radiotagging juveniles and estimating adult turnover with DNA-fingerprinting during 1993-1997. We gathered similar data during 1990-1998 to model populations of British buzzards (Buteo buteo), and during 1980-1998 to model populations of Swedish goshawks (Accipiter gentilis). Leg-bands and implanted microtransponders provided ways to test for bias and to estimate the harvest of sakers for falconry. Despite an estimated minimum first-year survival of only 23%, the observed productivity of 3.14 young per clutch would sustain a saker population (i.e., lambda = 1) with a breeding rate (at laying) of only 0.63 for adults or with a residual juvenile yield of 37% if all adults breed. Higher first-year survival rates for goshawks and buzzards correlated with juvenile yields of up to 71%, but no more than half as many individuals if adults also were harvested. An annual population decline of 40% for sakers in southern Kazakhstan could be explained by observed productivity of only 0.71 young per clutch if there was also an estimated harvest of 55% of adults. This study shows that demographic models such as these can now be built rapidly if nestlings are fitted with reliable and safe radiotags and adult turnover is estimated from genetic analyses or other techniques.
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| 9. |
- Kindberg, Jonas, et al.
(författare)
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Fluctuating mast production does not drive Scandinavian brown bear behavior
- 2019
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Ingår i: Journal of Wildlife Management. - : Wiley. - 0022-541X .- 1937-2817. ; 83, s. 657-668
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Tidskriftsartikel (refereegranskat)abstract
- Bears often rely on soft or hard mast during fall hyperphagia when they increase body mass in preparation for winter hibernation. Studies of North American and Japanese bear populations suggest they respond to years of mast crop failure by increasing movement rates and roaming farther, with an increase in human-wildlife conflicts. In southcentral Sweden, brown bears (Ursus arctos) primarily feed on bilberry (Vaccinium myrtillus) and lingonberry (V. vitis-idaea) during hyperphagia. We hypothesized that berry production affects movement, activity, and space use behaviors of bears in Sweden, which have the potential to increase human-bear encounters. We tested whether seasonal activity patterns, human settlement visits, and clearcut selection ratios were affected by bilberry and lingonberry productivity between 2007 and 2017 with linear and generalized linear mixed effect models. Contrary to our expectations, we did not find that bears moved more or maintained larger home ranges in years of low berry production. Bears were slightly more active in years of higher bilberry production, but variation in behavior was primarily explained by demographic group and individual differences. Bears rarely visited human settlements and the number of visits did not increase in relation to shortage of natural foods. Likewise, population-level selection for clearcuts was unrelated to berry production but reflected a differential food search behavior in the 2 peak berry seasons, with higher clearcut selection ratios during the lingonberry season. Only 12 bears regularly used agricultural fields, which were too few to relate field visits to berry production, but all bears visited fields more often during the later lingonberry season. We suggest that weaker fluctuations in berry production, a continuous spatial distribution of berries, and an apparent absence of forage-limiting exploitative intra- or interspecific competition contribute to brown bears in Scandinavia being less food limited than bears in North America or Japan, which might help to explain the low number of human-bear conflicts in Sweden. Factors potentially influencing encounters and actual or perceived conflict between bears and humans differ among populations because of a different distribution of natural and non-natural food resources or differences in the magnitude of variation in food abundance among years. These data are important to consider when communicating causes of human-wildlife conflicts to the public. (c) 2018 The Wildlife Society.
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| 10. |
- Kjellander, Petter
(författare)
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Beyond Climate Envelope Projections: Roe Deer Survival and Environmental Change
- 2016
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Ingår i: Journal of Wildlife Management. - : Wiley. - 0022-541X. ; 80, s. 452-464
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Tidskriftsartikel (refereegranskat)abstract
- Research on climate change impacts has focused on projecting changes in the geographic ranges of species, with less emphasis on the vital rates giving rise to species distributions. Managing ungulate populations under future climate change will require an understanding of how their vital rates are affected by direct climatic effects and the indirect climatic and non-climatic effects that are often overlooked by climate impact studies. We used generalized linear models and capture-mark-recapture models to assess the influence of a variety of direct climatic, indirect climatic, and non-climatic predictors on the survival of roe deer (Capreolus capreolus) at 2 sites in Sweden. The models indicated that although direct climatic effects (e.g., precipitation) explained some variation in survival, indirect climatic effects (e.g., an index of vegetation production), and non-climatic effects (hunting by lynx [Lynx lynx] and humans) had greater explanatory power. Climate change is likely to increase vegetation productivity in northern Europe, and, coupled with the positive effects of vegetation productivity on roe deer survival, might lead to population increases in the future. Survival was negatively affected by lynx presence where these predators occur and by human harvest in the site that lacked predators. In the future, managers might find that a combination of increased harvest and predation by recovering carnivore populations may be necessary to mitigate climate-induced increases in roe deer survival. Considering vegetation availability and predation effects is likely to improve predictions of ungulate population responses to variation in climate and, therefore, inform management under future climate change. (C) 2016 The Wildlife Society.
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