Fischer M.L.,University of Trier |
Sullivan M.J.P.,University of East Anglia |
Sullivan M.J.P.,University of Leeds |
Greiser G.,Johann Heinrich Von Thunen Institute |
And 9 more authors.
Biological Invasions | Year: 2016
As the second largest cause of biodiversity loss worldwide, there is an urgent need to study the dynamics of biological invasions and identify factors limiting the distribution of invasive alien species. In the present study we analyze national-scale hunting bag data from Germany to predict the dispersal of raccoons in the largest non-native population of the species. Our focus is (1) to document changes in the distribution and abundance of raccoons, (2) to identify the species–environment relationship and predict which areas will be suitable for future colonization and (3) to apply a dispersal model to predict how fast the raccoon will spread to these areas. The increase from about 9000 harvested raccoons in 2000/01 to about 71,000 in 2011/12 reflects the extensive amount of suitable habitat for this omnivorous species in Central Europe. The best model for explaining range expansion in Germany identified coverage of agriculture and fragmentation and coverage of forests as the most important explanatory variables. The range of raccoons (area with harvest index >0.1 per 100 ha) increased from 26,515 km2 in 2001 to 111,630 km2 in 2011, and is predicted to expand to 252,940 km2 by 2061, 71 % of the area of Germany. This vast area encompasses strategically important areas for conservation biology, such as wetlands with endangered native terrapins. The combination of merging of separated introduced populations and accelerating population growth highlights the potential for future impacts of raccoons on native communities, ecosystems and economic life in Germany and Central Europe. © 2015, Springer International Publishing Switzerland.
Gilg O.,University of Burgundy |
Moe B.,Norwegian Institute for Nature Research |
Hanssen S.A.,Norwegian Institute for Nature Research |
Schmidt N.M.,University of Aarhus |
And 16 more authors.
PLoS ONE | Year: 2013
The Long-tailed Skua, a small (<300 g) Arctic-breeding predator and seabird, is a functionally very important component of the Arctic vertebrate communities in summer, but little is known about its migration and winter distribution. We used light-level geolocators to track the annual movements of eight adult birds breeding in north-east Greenland (n = 3) and Svalbard (n = 5). All birds wintered in the Southern Hemisphere (mean arrival-departure dates on wintering grounds: 24 October-21 March): five along the south-west coast of Africa (0-40°S, 0-15°E), in the productive Benguela upwelling, and three further south (30-40°S, 0-50°E), in an area extending into the south-west Indian Ocean. Different migratory routes and rates of travel were documented during post-breeding (345 km d-1 in late August-early September) and spring migrations (235 km d-1 in late April) when most birds used a more westerly flyway. Among the different staging areas, a large region off the Grand Banks of Newfoundland appears to be the most important. It was used in autumn by all but one of the tracked birds (from a few days to three weeks) and in spring by five out of eight birds (from one to more than six weeks). Two other staging sites, off the Iberian coast and near the Azores, were used by two birds in spring for five to six weeks. Over one year, individuals travelled between 43,900 and 54,200 km (36,600-45,700 when excluding staging periods) and went as far as 10,500-13,700 km (mean 12,800 km) from their breeding sites. This study has revealed important marine areas in both the south and north Atlantic Ocean. Sustainable management of these ocean basins will benefit Long-tailed Skuas as well as other trans-equatorial migrants from the Arctic. © 2013 Gilg et al.
Dietz M.,Institute of Animal Ecology and Nature Education |
Dietz M.,University of Ulm |
Horig A.,Institute of Animal Ecology and Nature Education |
Horig A.,University of Ulm
Folia Zoologica | Year: 2011
Metabolic rate and body temperature (T b) reduction during torpor can provide significant energy savings for bats during inclement weather and food scarcity. However, torpor use may slow down biochemical processes including fetal and juvenile development and sperm production. Sex-differences in the timing of reproductive activity of bats in the temperate climate zone should result in differences of the thermoregulation behaviour by males and females during summer. To test this hypothesis, we studied thermoregulation of freeranging, tree-dwelling gleaning bats (Myotis bechsteinii) and trawling bats (M. daubentonii) during different reproductive periods. Gleaners and trawlers are able to forage on prey which is sitting on vegetation and the ground (gleaning) or which is slowly moving over water bodies (trawling). This prey is characterized by lower ambient temperature (T a) dependent abundance than flying prey. We used temperature-sensitive radio transmitters to measure skin temperature (T sk). Temperature telemetry over 144 census days revealed a significant effect of reproductive period and sex on T sk. Pre-spermatogenic males exhibited a significantly greater T sk reduction than females in early pregnancy. Males at the beginning of sperm production and in main spermatogenesis exhibited much more frequent and deeper temperature reductions than females in late pregnancy and in lactation. Lactating females maintained the highest T sk of all bats. Post-lactating females reduced T sk to the same extent or even more than males in advanced spermatogenesis. Our findings indicate that the thermoregulation of gleaning and trawling temperate bats is likely to be much less influenced by environmental conditions than that of aerial hawking bat species. We suggest that both sexes of Bechstein's bats and Daubenton's bats primarily adapt their thermoregulation in response to current reproductive activity.
Dietz M.,Institute of Animal Ecology and Nature Education |
Pir J.B.,rue des Carrefours |
Hillen J.,Institute of Animal Ecology and Nature Education
Biodiversity and Conservation | Year: 2013
Greater horseshoe bats (Rhinolophus ferrumequinum) and Geoffroy's bats (Myotis emarginatus) are two sympatric species that have undergone a serious population decline in Central Europe. In both species, population decline is likely to have been caused by habitat deterioration and habitat loss resulting in a decrease of carrying capacity. We examined the spatial ecology, habitat use and key landscape features in vital populations in R. ferrumequinum and M. emarginatus in the northern part of their current European distribution in Luxembourg. In total, 3,559 fixes from 26 radiotracked individuals were calculated. The tracked individuals of both species showed commuting flights along hedgerows, streams and small-forested patches. Maximum flight distances, home range sizes and habitat diversity did not differ between species, but R. ferrumequinum had significantly larger foraging ranges than adult M. emarginatus. Contrary to other studies, both bat species preferred semi-open, but richly structured traditional farmland habitats such as orchards, pastures and parkland habitats instead of available large broad-leaved deciduous forests. M. emarginatus frequently preyed on abundant arthropod resources in cowsheds, sometimes even exclusively throughout the night. The landscape configuration around the buffered radio fixes of adult R. ferrumequinum and M. emarginatus differed significantly from that around analysed random buffers. Radio fixes were concentrated in a landscape characterised by higher habitat diversity than in the surrounding region. Our results support the concept of a 'biocultural link' between traditional land use and biodiversity, and we therefore strongly recommend the conservation of extensive traditional land use practices, which will help to preserve both endangered bat species along with the local biodiversity. © 2013 Springer Science+Business Media Dordrecht.
Dawo B.,University of Ulm |
Dawo B.,Institute of Animal Ecology and Nature Education |
Kalko E.K.V.,University of Ulm |
Dietz M.,University of Ulm |
Dietz M.,Institute of Animal Ecology and Nature Education
Annales Zoologici Fennici | Year: 2013
An understanding of the spatial organization of endangered species is particularly important in the light of habitat degradation and fragmentation. In bats, little is known about whether and how space is organized between individuals of the same species. We investigated space use in four maternity colonies of Bechstein's bats. We were able to show for the first time that spatial organization reflects the social organization in Bechstein's bats. We found a strong segregation of foraging ranges within colonies, and an even stronger segregation between different colonies. Our results suggest that the spatial organization of females is determined by foraging efficiency. It is crucial to determine the essential characteristics of both feeding and roosting core areas. We provide a precise prediction of effective population size and space requirements. Thereby, implications for the protection of Bechstein's bats and assumedly also for other bat species with a similar social and spatial organization can be deduced. © Finnish Zoological and Botanical Publishing Board 2013.