@article{ZurellEggersKaatzetal.2015, author = {Zurell, Damaris and Eggers, Ute and Kaatz, Michael and Rotics, Shay and Sapir, Nir and Wikelski, Martin and Nathan, Ran and Jeltsch, Florian}, title = {Individual-based modelling of resource competition to predict density-dependent population dynamics: a case study with white storks}, series = {Oikos}, volume = {124}, journal = {Oikos}, number = {3}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0030-1299}, doi = {10.1111/oik.01294}, pages = {319 -- 330}, year = {2015}, abstract = {Density regulation influences population dynamics through its effects on demographic rates and consequently constitutes a key mechanism explaining the response of organisms to environmental changes. Yet, it is difficult to establish the exact form of density dependence from empirical data. Here, we developed an individual-based model to explore how resource limitation and behavioural processes determine the spatial structure of white stork Ciconia ciconia populations and regulate reproductive rates. We found that the form of density dependence differed considerably between landscapes with the same overall resource availability and between home range selection strategies, highlighting the importance of fine-scale resource distribution in interaction with behaviour. In accordance with theories of density dependence, breeding output generally decreased with density but this effect was highly variable and strongly affected by optimal foraging strategy, resource detection probability and colonial behaviour. Moreover, our results uncovered an overlooked consequence of density dependence by showing that high early nestling mortality in storks, assumed to be the outcome of harsh weather, may actually result from density dependent effects on food provision. Our findings emphasize that accounting for interactive effects of individual behaviour and local environmental factors is crucial for understanding density-dependent processes within spatially structured populations. Enhanced understanding of the ways animal populations are regulated in general, and how habitat conditions and behaviour may dictate spatial population structure and demographic rates is critically needed for predicting the dynamics of populations, communities and ecosystems under changing environmental conditions.}, language = {en} } @article{ZurellvonWehrdenRoticsetal.2018, author = {Zurell, Damaris and von Wehrden, Henrik and Rotics, Shay and Kaatz, Michael and Gross, Helge and Schlag, Lena and Sch{\"a}fer, Merlin and Sapir, Nir and Turjeman, Sondra and Wikelski, Martin and Nathan, Ran and Jeltsch, Florian}, title = {Home range size and resource use of breeding and non-breeding white storks along a land use gradient}, series = {Frontiers in Ecology and Evolution}, volume = {6}, journal = {Frontiers in Ecology and Evolution}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {2296-701X}, doi = {10.3389/fevo.2018.00079}, pages = {11}, year = {2018}, abstract = {Biotelemetry is increasingly used to study animal movement at high spatial and temporal resolution and guide conservation and resource management. Yet, limited sample sizes and variation in space and habitat use across regions and life stages may compromise robustness of behavioral analyses and subsequent conservation plans. Here, we assessed variation in (i) home range sizes, (ii) home range selection, and (iii) fine-scale resource selection of white storks across breeding status and regions and test model transferability. Three study areas were chosen within the Central German breeding grounds ranging from agricultural to fluvial and marshland. We monitored GPS-locations of 62 adult white storks equipped with solar-charged GPS/3D-acceleration (ACC) transmitters in 2013-2014. Home range sizes were estimated using minimum convex polygons. Generalized linear mixed models were used to assess home range selection and fine-scale resource selection by relating the home ranges and foraging sites to Corine habitat variables and normalized difference vegetation index in a presence/pseudo-absence design. We found strong variation in home range sizes across breeding stages with significantly larger home ranges in non-breeding compared to breeding white storks, but no variation between regions. Home range selection models had high explanatory power and well predicted overall density of Central German white stork breeding pairs. Also, they showed good transferability across regions and breeding status although variable importance varied considerably. Fine-scale resource selection models showed low explanatory power. Resource preferences differed both across breeding status and across regions, and model transferability was poor. Our results indicate that habitat selection of wild animals may vary considerably within and between populations, and is highly scale dependent. Thereby, home range scale analyses show higher robustness whereas fine-scale resource selection is not easily predictable and not transferable across life stages and regions. Such variation may compromise management decisions when based on data of limited sample size or limited regional coverage. We thus recommend home range scale analyses and sampling designs that cover diverse regional landscapes and ensure robust estimates of habitat suitability to conserve wild animal populations.}, language = {en} } @article{RoticsKaatzResheffetal.2016, author = {Rotics, Shay and Kaatz, Michael and Resheff, Yehezkel S. and Turjeman, Sondra Feldman and Zurell, Damaris and Sapir, Nir and Eggers, Ute and Flack, Andrea and Fiedler, Wolfgang and Jeltsch, Florian and Wikelski, Martin and Nathan, Ran}, title = {The challenges of the first migration: movement and behaviour of juvenile vs. adult white storks with insights regarding juvenile mortality}, series = {Journal of animal ecology : a journal of the British Ecological Society}, volume = {85}, journal = {Journal of animal ecology : a journal of the British Ecological Society}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0021-8790}, doi = {10.1111/1365-2656.12525}, pages = {938 -- 947}, year = {2016}, abstract = {1. Migration conveys an immense challenge, especially for juvenile birds coping with enduring and risky journeys shortly after fledging. Accordingly, juveniles exhibit considerably lower survival rates compared to adults, particularly during migration. Juvenile white storks (Ciconia ciconia), which are known to rely on adults during their first fall migration presumably for navigational purposes, also display much lower annual survival than adults. 2. Using detailed GPS and body acceleration data, we examined the patterns and potential causes of age-related differences in fall migration properties of white storks by comparing first-year juveniles and adults. We compared juvenile and adult parameters of movement, behaviour and energy expenditure (estimated from overall dynamic body acceleration) and placed this in the context of the juveniles' lower survival rate. 3. Juveniles used flapping flight vs. soaring flight 23\% more than adults and were estimated to expend 14\% more energy during flight. Juveniles did not compensate for their higher flight costs by increased refuelling or resting during migration. When juveniles and adults migrated together in the same flock, the juvenile flew mostly behind the adult and was left behind when they separated. Juveniles showed greater improvement in flight efficiency throughout migration compared to adults which appears crucial because juveniles exhibiting higher flight costs suffered increased mortality. 4. Our findings demonstrate the conflict between the juveniles' inferior flight skills and their urge to keep up with mixed adult-juvenile flocks. We suggest that increased flight costs are an important proximate cause of juvenile mortality in white storks and likely in other soaring migrants and that natural selection is operating on juvenile variation in flight efficiency.}, language = {en} } @article{TuckerBoehningGaeseFaganetal.2018, author = {Tucker, Marlee A. and Boehning-Gaese, Katrin and Fagan, William F. and Fryxell, John M. and Van Moorter, Bram and Alberts, Susan C. and Ali, Abdullahi H. and Allen, Andrew M. and Attias, Nina and Avgar, Tal and Bartlam-Brooks, Hattie and Bayarbaatar, Buuveibaatar and Belant, Jerrold L. and Bertassoni, Alessandra and Beyer, Dean and Bidner, Laura and van Beest, Floris M. and Blake, Stephen and Blaum, Niels and Bracis, Chloe and Brown, Danielle and de Bruyn, P. J. Nico and Cagnacci, Francesca and Calabrese, Justin M. and Camilo-Alves, Constanca and Chamaille-Jammes, Simon and Chiaradia, Andre and Davidson, Sarah C. and Dennis, Todd and DeStefano, Stephen and Diefenbach, Duane and Douglas-Hamilton, Iain and Fennessy, Julian and Fichtel, Claudia and Fiedler, Wolfgang and Fischer, Christina and Fischhoff, Ilya and Fleming, Christen H. and Ford, Adam T. and Fritz, Susanne A. and Gehr, Benedikt and Goheen, Jacob R. and Gurarie, Eliezer and Hebblewhite, Mark and Heurich, Marco and Hewison, A. J. Mark and Hof, Christian and Hurme, Edward and Isbell, Lynne A. and Janssen, Rene and Jeltsch, Florian and Kaczensky, Petra and Kane, Adam and Kappeler, Peter M. and Kauffman, Matthew and Kays, Roland and Kimuyu, Duncan and Koch, Flavia and Kranstauber, Bart and LaPoint, Scott and Leimgruber, Peter and Linnell, John D. C. and Lopez-Lopez, Pascual and Markham, A. Catherine and Mattisson, Jenny and Medici, Emilia Patricia and Mellone, Ugo and Merrill, Evelyn and Mourao, Guilherme de Miranda and Morato, Ronaldo G. and Morellet, Nicolas and Morrison, Thomas A. and Diaz-Munoz, Samuel L. and Mysterud, Atle and Nandintsetseg, Dejid and Nathan, Ran and Niamir, Aidin and Odden, John and Oliveira-Santos, Luiz Gustavo R. and Olson, Kirk A. and Patterson, Bruce D. and de Paula, Rogerio Cunha and Pedrotti, Luca and Reineking, Bjorn and Rimmler, Martin and Rogers, Tracey L. and Rolandsen, Christer Moe and Rosenberry, Christopher S. and Rubenstein, Daniel I. and Safi, Kamran and Said, Sonia and Sapir, Nir and Sawyer, Hall and Schmidt, Niels Martin and Selva, Nuria and Sergiel, Agnieszka and Shiilegdamba, Enkhtuvshin and Silva, Joao Paulo and Singh, Navinder and Solberg, Erling J. and Spiegel, Orr and Strand, Olav and Sundaresan, Siva and Ullmann, Wiebke and Voigt, Ulrich and Wall, Jake and Wattles, David and Wikelski, Martin and Wilmers, Christopher C. and Wilson, John W. and Wittemyer, George and Zieba, Filip and Zwijacz-Kozica, Tomasz and Mueller, Thomas}, title = {Moving in the Anthropocene}, series = {Science}, volume = {359}, journal = {Science}, number = {6374}, publisher = {American Assoc. for the Advancement of Science}, address = {Washington}, issn = {0036-8075}, doi = {10.1126/science.aam9712}, pages = {466 -- 469}, year = {2018}, abstract = {Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission.}, language = {en} }