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Countries that allow sport hunting of African lions, Panthera leo, increasingly are mandating minimum age regulations for harvested individuals that require accurate aging techniques. However, individual variation in dental characteristics used for aging could result in errors and has not been quantified. We assessed individual variation in three dental methods for estimating age of lions using left and right paired PM2s from 31 free-ranging lions of unknown age from Zambia. Assignment of individuals to age class based on crown wear was largely consistent (87%) between paired PM2s; measures of pulp chamber closure also were highly consistent (< 4% variation) between pairs. Though pulp chamber closure varied little between pairs, calibrating pulp closure with known-aged lions is needed to fully develop this method. In contrast, cementum line counts differed between paired PM2s in 94% of lions, ranging from 1 to 7 cementum lines (i.e. 0.5–3.5 years). Of lions with cementum lion counts that differed between teeth, 45% were estimated as meeting the 5- or 6-year-old minimum age used in trophy lion monitoring programs with one PM2, but not the paired PM2. Though individual variation in cementum line counts may render this technique unsuitable for aging lions, using the maximum or average count from both PM2s warrants further investigation. Individual variation in dental characteristics should be considered when developing lion aging techniques based on dentition.
The populations of Alpine chamois Rupicapra rupicapra rupicapra are currently not at risk of extinction, but local population declines have been observed in some areas. Competition with other herbivore species may be one of the causes for this decline. The present research aims at describing the autumnal diet and preferences of Alpine chamois living in sympatry with red deer Cervus elaphus and roe deer Capreolus capreolus in central Italian Alps and to verify the presence of spatial and diet overlap among these herbivore species. We analyzed the rumen content of 35 samples collected during the hunting season from animals culled in Val Fontana. The results were integrated by data previously collected on rumen content of red deer and roe deer and on space use of the three herbivore species in the same study area. We identified 26 species and 15 genera belonging to 21 plant families of the 51 available in the study area. Monocotyledon families were the most frequently represented in chamois diet composition (78.11%), followed by Ericaceae (5.30%), Betulaceae (4.32%) and Cupressaceae (3.37%). All results showed similar diet between genders. Chamois diet was more similar to red deer than to roe deer diet. The diet selection index (W) showed that on the east-facing side of the valley some species (Calluna vulgaris: Wm = 5.27; Juniperus communis: Wm = 4.24; Loiseleuria procumbens: Wm = 4.82) were selected above their availability, perhaps as a consequence of the higher spatial overlap on this side between chamois and red deer, which make similar use of vegetal resources. Although competition among species is unlikely, due to the low population densities, over-exploitation of food resources and food niche overlap may be future limiting factors for local chamois population, and they should be taken into account for the proper management and control of wild and domestic ruminants.
Agricultural intensification often leads to fragmentation of natural habitats, such as forests, and thereby negatively affects forest specialist species. However, human introduced habitats, such as hedges, may counteract negative effects of forest fragmentation and increase dispersal, particularly of forest specialists. We studied effects of habitat type (forest edge versus hedge) and hedge isolation from forests (connected versus isolated hedge) in agricultural landscapes on abundance, species richness and community composition of mice, voles and shrews in forest edges and hedges. Simultaneously to these effects of forest edge/hedge type we analysed impacts of habitat structure, namely percentage of bare ground and forest edge/hedge width, on abundance, species richness and community composition of small mammals. Total abundance and forest specialist abundance (both driven by the most abundant species Myodes glareolus, bank vole) were higher in forest edges than in hedges, while hedge isolation had no effect. In contrast, abundance of habitat generalists was higher in isolated compared to connected hedges, with no effect of habitat type (forest edge versus hedge). Species richness as well as abundance of the most abundant habitat generalist Sorex araneus (common shrew), were not affected by habitat type or hedge isolation. Decreasing percentage of bare ground and increasing forest edge/hedge width was associated with increased abundance of forest specialists, while habitat structure was unrelated to species richness or abundance of any other group. Community composition was driven by forest specialists, which exceeded habitat generalist abundance in forest edges and connected hedges, while abundances were similar to each other in isolated hedges. Our results show that small mammal forest specialists prefer forest edges as habitats over hedges, while habitat generalists are able to use unoccupied ecological niches in isolated hedges. Consequently even isolated hedges can be marginal habitats for forest specialists and habitat generalists and thereby may increase regional farmland biodiversity.
Populations of wide-ranging species are likely to extend across multiple jurisdictions, including national and international borders. This requires that local institutions implement data sharing and a standardization of monitoring designs. However, a formal evaluation of the benefits of integrated monitoring systems had not, of yet, been performed. Using the wolverines in central Scandinavia as a study case, we assessed the benefits of data sharing for the monitoring of trans-boundary populations. We also assessed the performance of two demographic monitoring systems, one relying on a count of reproductive units, the other resulting from non-invasive genetic sampling and capture-recapture modeling. Sharing data across the border between Norway and Sweden allowed a strong increase in the precision of population size, population growth rate and vital rates estimates. It also allowed revealing that the probability to emigrate from Sweden to Norway was significantly higher than in the opposite direction, a required condition for the existence of a source—sink dynamics. These findings would have been impossible without trans-boundary data sharing. While the den count monitoring provided an estimated population growth of 138% over the 12-year period, the DNA-based estimate was only 72%. A positive trend likely occurred in the detectability of wolverine dens during the first years of the study, and the index was not able to separate the actual demographic trend from the trend in the system's ability to detect reproductions, thus providing positively biased estimates of population growth rate during the initial phase of the study. Data sharing is a crucial need for the study of the processes occurring in trans-boundary populations. It should be enhanced wherever trans-boundary ecological processes occur. Also, managers should be aware that count-based monitoring has a risk of overestimating population growth during the first years after its implementation.
Understanding a species' feeding ecology is essential for successful management and conservation, because food abundance can influence body mass, survival, reproductive success, movements, and habitat use. We describe annual and seasonal variations in the diet of brown bears Ursus arctos in southcentral Sweden, based on analysis of 527 fecal samples from 1994–1996 and 2000–2001. There was distinct seasonal variation in most of the 26 food items we documented. Ungulates, predominantly moose Alces alces, and insects comprised most of the estimated dietary energy content in spring and summer. Insects were represented almost entirely by ants, of which Formica spp. and Camponotus herculeanus were the most common. During autumn, berries dominated the diet. The most important berry species were bilberry Vaccinium myrtillus, crowberry Empetrum hermaphoditum and lingonberry V. vitis-idaea. We determined berry availability by inventorying 308 random plots three times for two consecutive years. These three berries occurred with great spatial, seasonal and annual variation in abundance. The bears showed the strongest positive preference for bilberries, a lesser positive preference for crowberries, but no preference for lingonberries. The proportion of berries in the autmn diet was stable between years, but the relative importance of the species changed, indicating that bears switched to crowberries when bilberries were less abundant. The effects of predicted future climatic change might have severe effects on the availability of the berries, which is the only important food available for fat acquisition prior to hibernation.
One key assumption often inferred with using radio-equipped individuals is that the transmitter has no effect on the metric of interest. To evaluate this assumption, we used a known fate model to assess the effect of transmitter type (i.e. tail-mounted or peritoneal implant) on short-term (one year) survival and a joint live—dead recovery model and results from a mark—recapture study to compare long-term (eight years) survival and body condition of ear-tagged only American beavers Castor canadensis to those equipped with radio transmitters in Voyageurs National Park, Minnesota, USA. Short-term (1-year) survival was not influenced by transmitter type (wi = 0.64). Over the 8-year study period, annual survival was similar between transmitter-equipped beavers (tail-mounted and implant transmitters combined; 0.76; 95% CI = 0.45–0.91) versus ear-tagged only (0.78; 95% CI = 0.45–0.93). Additionally, we found no difference in weight gain (t9 = 0.25, p = 0.80) or tail area (t11 = 1.25, p = 0.24) from spring to summer between the two groups. In contrast, winter weight loss (t22 = - 2.03, p = 0.05) and tail area decrease (t30 = - 3.04, p = 0.01) was greater for transmitterequipped (weight = - 3.09 kg, SE = 0.55; tail area = - 33.71 cm2, SE = 4.80) than ear-tagged only (weight = - 1.80 kg, SE = 0.33; tail area = - 12.38 cm2, SE = 5.13) beavers. Our results generally support the continued use of transmitters on beavers for estimating demographic parameters, although we recommend additional assessments of transmitter effects under different environmental conditions.
Tail-mounted transmitters have been used successfully in temperate regions of North America and Europe but have not been tested in more northern parts of American beaver Castor canadensis range. We deployed 63 tail-mounted transmitters on adult beavers in Voyageurs National Park, Minnesota (USA; 48°30′N, 92°50′W), at the southern edge of the boreal forest. Mean transmitter retention time was 133 days (range = 18–401, SD = 101), with only 7% retained > 12 months. Males and females did not differ in retention times. Retention time was similar for transmitters deployed in fall (n = 38, = 135 days) and spring (n = 21, = 130 days). In 24 cases where we confirmed beavers lost transmitters, 63% tore through the side of the tail, 25% pulled out through a widened attachment hole, and 13% had the lock-nut unscrew. Beavers chewed off or pulled out whip antennas on 50% of transmitters before they were detached from the tail, which reduced VHF signal strength and detection distance. The likelihood that an antenna would be damaged increased 3.8 times for each day of deployment up to 371 days. On average, beavers with transmitters lost 23% of their body mass and 26% of tail thickness over winter, and regained similar percentages over the growing season. Retention rates and retention times of tail transmitters were much lower in Voyageurs National Park relative to more southern areas in the United States where intra-annual variability in body condition is considerably less. Our results reaffirm that methodologies developed for wildlife telemetry or other research and monitoring techniques should be tested under different environmental conditions to ensure objectives can be met in a safe and efficient manner.
Combining radio-telemetry with direct observations, we followed 22 released juvenile captive-bred capercaillies throughout the day to assess if their seasonal and daily patterns of activity, movements, and diet are in accordance with published information on wild birds. Day length was the most important factor determining birds' mobility and activity. Capercaillies were active for 46 ± 2% of daytime, during which they mostly foraged (30 ± 2%). The average distance travelled per day was 0.93 ± 0.14 km. The time budget of capercaillies was mostly allocated to activities on the ground but they spent at least 20% of the daytime in trees. They fed primarily on blueberries, cowberries and pine needles. The mean daily feeding time in fall and winter was 3 h, but it increased to 6 h in spring and summer. We conclude that released birds behave similarly to wild birds and reintroduction of captive-bred capercaillies can be successful if the initial mortality is reduced.