Short-term survival and dispersal of translocated European wild rabbits. Improving the release protocol

Translocation of European wild rabbit Oryctolagus cuniculus L. is one of the most frequent management tools to increase rabbit density in Spain, both as prey of several predators that are threatened with extinction and for sport hunting. Nevertheless the elevated short-term mortality by predation makes translocations unsuccessful and increases their biological cost. Information on the factors affecting the short-term survival and dispersal of translocated rabbits is required to improve release management and increase performance of translocated rabbits, and to avoid the use of non-selective lethal methods for predator control. In this study we tested electric fencing and night-shooting as alternative to traditional release protocols, and the effects of vegetation cover and warren fencing on short-term survival and dispersal of rabbits. Night shooting performed during the first nights after release increased significantly the survival of rabbits, by hindering the activity of carnivores in the release area. The use of an electric fence enclosure also increased the performance of rabbits, but was not efficient to constraint rabbit dispersal. Rabbits released in areas with low vegetation cover showed higher mortality and dispersal distances than rabbits released in high cover areas. Warren fencing decreased both the dispersal of rabbits and the adverse impact of predation in low cover areas, but had no effect in high cover areas. Selection of high cover areas or warren fencing in low cover areas seem to be the most advantageous release conditions to decrease the short-term predation impact, reducing the biological cost of rabbit translocations and the risks for endangered predators derived from the use of traditional predator control practices during translocations.     

Sex differences in population genetics, home range size and habitat use of the parti-colored bat (Vespertilio murinus, Linnaeus 1758) in Switzerland and their consequences for conservation

When habitats are declining, niche segregation by demographic groups, such as the two sexes, can have a profound impact on the extinction risk of a species as a whole. Thus, differences in the requirements of demographic groups are of importance in conservation. We combined behavioural and genetic data to investigate whether the sexually segregated parti-colored bat (Vespertilio murinus) exhibits sex-specific niche partitioning. We use our data to evaluate implications for conservation of this potentially vulnerable species in Switzerland, the western boundary of its range. Using radio-telemetry, we found sex-specific differences in habitat use. Foraging females strongly relied on lakes while foraging males displayed more flexibility in their habitat use. Moreover, males covered significantly larger foraging areas than females. Sequencing 341 base pairs of the mitochondrial D-loop of 247 individuals revealed sex-specific differences in the genetic structure of colonies, but no such difference was observed for three nuclear micro-satellite markers. We found high mtDNA diversity in two Swiss male colonies and one German female colony, but low mtDNA diversity in two Swiss female colonies. Our genetic data suggest that considerable gene flow occurs via male dispersal and mating. At the same time immigration of females into the existing female colonies in Switzerland is rare compared to the immigration of new males into male colonies. Since we found the sexes in Vespertilio murinus to differ markedly in their ecology, population genetics, and behaviour, we conclude that sex-specific conservation plans are required to protect this species efficiently.     

Spring habitat selection of sables in Daxing’an Mountains

This paper studies the habitat selection of sables (Martes. zibellina) in spring adopting radio-tracking and GPS (Global Positioning System) in Daxing’an Mountains of China. Sables liked mature and elder forest, but it avoided uncovered and young growth land. In spring sables had strong selection to medium cover-degree forest, but it avoided widen ground and especial high cover-degree forest. On the contrary sables didn’t have the strong selection to shrubs cover-degree, but strong selection to dominant tree species, slope degree and slope direction, especially sable liked medium and lower slope. At the same time, sables had the strong selection to the log’s density and the crown’s cover-degree. Generally it avoided high elevation and lower slope land. Responsible editor. Chai Ruihai.     

Spring habitat selection of sables in Daxing''''an Mountains

IntroductionSables(Marfes.zibellina),rarefur-bearinganimal,belongedtocarnivore,andscatteredinNorth-Asiacontinentanditsisland,suchasfRussiaMongoIiaandKorea,etc.TherewerefoursubspeciesinNorth-eastandXinjiangofChinafM.ZprincePs,Birula,M.ZLiRkouensisMaEtWu,M.Zhamenensis.KiskidaandM.ZaltaiCa(Ma1981).Sables,asatypicalanimalofsub-frigidzoneconif-eroustrees,wasknownasoneofthreetreasuresinNortheastforitsfur.Now,itwaslookedasthefirstclassprotectedanimalinourcountry.OursabtewasmainlyinDaxing…     

Radio-telemetry increases free-living energy costs in the endangered Takahe Porphyrio mantelli

An assumption of most radio-telemetry studies is that the technique does not affect the behaviour or physiology of the study animal in any important way. However, previous work has shown that radio-tags can elevate the energy costs of activities such as flying and swimming, which may have implications for survival. Using an experimental approach, we assess the impact of tag-bearing on the free-living energy expenditure of a large, relatively inactive, non-swimming bird: based on previous assumptions, it would be expected to be trivial. Daily energy expenditure increased by 8.5% in the flightless Takahe when they were carrying radio-tags. We can rule out several potential sources of elevated living-costs due to tags, and conclude that a greater thermoregulatory effort was likely to be the main factor involved. This increase in energy expenditure could potentially reduce survival in this endangered species, particularly in its montane habitat in winter.     

紫貂巢区的研究

１９９４～１９９６年,在大兴安岭地区采用无线电跟踪技术和全球定位系统（ＧＰＳ）对紫貂巢区进行了研究。结果表明,紫貂通常具有比较稳定的巢区（４．３～１７．３ｋｍ＾２）;雄性个体巢区大于雌性：四季巢区不同。冬季最大,夏季最小;巢区重叠多发生于异性个体间,雄性个体巢区几乎不重叠。影响巢区大小的因素主要为动物性别、食物丰富度等。     

Survival, dispersal and early migration movements of captive-bred juvenile eastern loggerhead shrikes (Lanius ludovicianus migrans)

Avian captive breeding programs pose a particular challenge with migratory birds due to natal dispersal and high mortality during migration. In Canada a captive breeding program for the eastern loggerhead shrike (Lanius ludovicianus migrans) has released over 400 juveniles since 2001, but the fate of almost all these birds is unknown. In 2007 and 2008, we used radio-telemetry of captive-reared juveniles to determine pre-migration survival and dispersal movements away from the release site. Overall, 76% (29 of 38) of shrikes survived from release to the initiation of migration and the daily survival rate was 0.987. Most deaths (78%) occurred in females, suggesting a possible sex-biased pre-migration mortality. Shrikes typically dispersed independently, there was little overlap between dispersal sites, and the average pre-migration dispersal distance from the release site was 4.2 km (SD 2.4). Release date was negatively correlated with time spent at the release site prior to dispersal, but did not have a significant effect on survival, time spent at dispersal sites or distance of dispersal. Migration initiation date ranged over 6 weeks and early-hatched juveniles were the first to begin migration. Using aerial telemetry, we located five of 29 birds that had begun migration at distances up to 180 km from the release site; no birds were found dead after initiating migration despite the extensive search area. High juvenile survival to migration for captive-reared juveniles suggests that the captive breeding and release program has high potential to augment wild populations of the eastern loggerhead shrike.     

紫貂冬季生境选择的初步研究

采用无线电跟踪技术和全球定位系统对大兴安岭阿巴河流域紫貂冬季的生境选择进行了研究。结果表明,紫貂偏好成熟林地和老龄林地。（１）紫貂冬季栖息地主要的优势树种是落叶松林。对中等盖度的林地选择性强,而不选择开阔地带和特别高盖度地区。（２）主要栖息中,下坡位,而对上坡位选择性不强;（３）对小树密度,大树密度,乔木胸径,倒木长度,倒木密度,倒木直径等有正选择性。     

Foraging site fidelity shapes the spatial organisation of a population of female western barbastelle bats

Information about the spatial distribution of individual foraging habitats, which determines the space required by a population to be viable, is vitally important for the conservation of bats. Detailed knowledge of this kind is crucial for the design of nature reserves and management plans. Recent field studies that examined habitat use and home range distribution of bats largely ignored factors like traditional range use vs. intra- and interspecific competition, which may be responsible for the spatial organisation of a population home range. We investigated the home range sizes and distribution of a maternity colony of the western barbastelle bat via radio telemetry in four consecutive tracking sessions (2004-2007). Based on 19 data sets with a total of 2737 fixes obtained from 12 females, we examined (i) how colony members partition the population home range (home range overlap analysis), and (ii) if individuals tracked over several years exhibit site fidelity. Home range sizes ranged from 125 to 2551 ha (median: 403 ha), with a median number of 2 core areas (range: 1-5 core areas per individual per year). The core area sizes ranged from 5 to 285 ha (median: 67 ha). A home range and core area overlap analysis showed that site fidelity across years seems to be more important for home range distribution than competition among colony members. This allows researchers to combine information from several years to get a deeper insight into the population’s spatial requirements.