@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{TurjemanCentenoCuadrosEggersetal.2016, author = {Turjeman, Sondra Feldman and Centeno-Cuadros, Alejandro and Eggers, Ute and Rotics, Shay and Blas, Julio and Fiedler, Wolfgang and Kaatz, Michael and Jeltsch, Florian and Wikelski, Martin and Nathan, Ran}, title = {Extra-pair paternity in the socially monogamous white stork (Ciconia ciconia) is fairly common and independent of local density}, series = {Scientific reports}, volume = {6}, journal = {Scientific reports}, publisher = {Nature Publ. Group}, address = {London}, issn = {2045-2322}, doi = {10.1038/srep27976}, pages = {9}, year = {2016}, abstract = {Although many birds are socially monogamous, most (>75\%) studied species are not strictly genetically monogamous, especially under high breeding density. We used molecular tools to reevaluate the reproductive strategy of the socially monogamous white stork (Ciconia ciconia) and examined local density effects. DNA samples of nestlings (Germany, Spain) were genotyped and assigned relationships using a two-program maximum likelihood classification. Relationships were successfully classified in 79.2\% of German (n = 120) and 84.8\% of Spanish (n = 59) nests. For each population respectively, 76.8\% (n = 73) and 66.0\% (n = 33) of nests contained only full-siblings, 10.5\% (n = 10) and 18.0\% (n = 9) had half-siblings (at least one nestling with a different parent), 3.2\% (n = 3) and 10.0\% (n = 5) had unrelated nestlings (at least two nestlings, each with different parents), and 9.5\% (n = 9) and 6.0\% (n = 3) had "not full-siblings" (could not differentiate between latter two cases). These deviations from strict monogamy place the white stork in the 59th percentile for extra-pair paternity among studied bird species. Although high breeding density generally increases extra-pair paternity, we found no significant association with this species' mating strategies. Thus although genetic monogamy is indeed prominent in the white stork, extra-pair paternity is fairly common compared to other bird species and cannot be explained by breeding density.}, 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{JeltschBontePeeretal.2013, author = {Jeltsch, Florian and Bonte, Dries and Peer, Guy and Reineking, Bj{\"o}rn and Leimgruber, Peter and Balkenhol, Niko and Schr{\"o}der-Esselbach, Boris and Buchmann, Carsten M. and M{\"u}ller, Thomas and Blaum, Niels and Zurell, Damaris and B{\"o}hning-Gaese, Katrin and Wiegand, Thorsten and Eccard, Jana and Hofer, Heribert and Reeg, Jette and Eggers, Ute and Bauer, Silke}, title = {Integrating movement ecology with biodiversity research - exploring new avenues to address spatiotemporal biodiversity dynamics}, doi = {10.1186/2051-3933-1-6}, year = {2013}, language = {en} } @misc{JeltschBontePe'eretal.2013, author = {Jeltsch, Florian and Bonte, Dries and Pe'er, Guy and Reineking, Bj{\"o}rn and Leimgruber, Peter and Balkenhol, Niko and Schr{\"o}der-Esselbach, Boris and Buchmann, Carsten M. and M{\"u}ller, Thomas and Blaum, Niels and Zurell, Damaris and B{\"o}hning-Gaese, Katrin and Wiegand, Thorsten and Eccard, Jana and Hofer, Heribert and Reeg, Jette and Eggers, Ute and Bauer, Silke}, title = {Integrating movement ecology with biodiversity research}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-401177}, pages = {13}, year = {2013}, abstract = {Movement of organisms is one of the key mechanisms shaping biodiversity, e.g. the distribution of genes, individuals and species in space and time. Recent technological and conceptual advances have improved our ability to assess the causes and consequences of individual movement, and led to the emergence of the new field of 'movement ecology'. Here, we outline how movement ecology can contribute to the broad field of biodiversity research, i.e. the study of processes and patterns of life among and across different scales, from genes to ecosystems, and we propose a conceptual framework linking these hitherto largely separated fields of research. Our framework builds on the concept of movement ecology for individuals, and demonstrates its importance for linking individual organismal movement with biodiversity. First, organismal movements can provide 'mobile links' between habitats or ecosystems, thereby connecting resources, genes, and processes among otherwise separate locations. Understanding these mobile links and their impact on biodiversity will be facilitated by movement ecology, because mobile links can be created by different modes of movement (i.e., foraging, dispersal, migration) that relate to different spatiotemporal scales and have differential effects on biodiversity. Second, organismal movements can also mediate coexistence in communities, through 'equalizing' and 'stabilizing' mechanisms. This novel integrated framework provides a conceptual starting point for a better understanding of biodiversity dynamics in light of individual movement and space-use behavior across spatiotemporal scales. By illustrating this framework with examples, we argue that the integration of movement ecology and biodiversity research will also enhance our ability to conserve diversity at the genetic, species, and ecosystem levels.}, language = {en} } @article{EggersArensFirlaetal.2015, author = {Eggers, Ute and Arens, Michael and Firla, Mario and Wallschl{\"a}ger, Hans-Dieter}, title = {To fledge or not to fledge: factors influencing the number of eggs and the eggs-to-fledglings rate in White Storks Ciconia ciconia in an agricultural environment}, series = {Journal of ornithology}, volume = {156}, journal = {Journal of ornithology}, number = {3}, publisher = {Springer}, address = {New York}, issn = {0021-8375}, doi = {10.1007/s10336-015-1182-9}, pages = {711 -- 723}, year = {2015}, abstract = {Numerous studies have explored the relationship between environmental factors and White Stork Ciconia ciconia reproduction, mainly expressing breeding success as the number of fledglings. Nonetheless, one of the most critical life-history stages in birds falls between egg-laying and fledging, and identifying the factors causing offspring mortality during this period provides valuable knowledge. We quantified the number of laid White Stork eggs and the proportion of eggs that turned into fledglings in an agriculture-dominated region in Eastern Germany. Moreover, we identified the factors among land cover, weather and arrival dates, which influenced these two reproductive measures the most, and analysed the monitored mortality causes. On average, four eggs were laid per nest, and 57.8 \% of the eggs turned into fledglings. The number of eggs laid was best explained by the negative effect of the arrival date of the second stork, while the percentage of eggs that turned into fledglings was more dependent on weather: most important parameters were mean temperature in the fifth and seventh weeks after the assumed breeding start (i.e. around the assumed hatching date), and the number of consecutive days with precipitation when nestlings are assumed to be approximately 3 weeks old. In an agricultural environment, weather effects that potentially disturb food availability might be more important than effects directly affecting the survival of White Stork offspring. The most frequent observed mortality cause, nest fights, furthermore revealed the relevance of intraspecific competition in the study population.}, language = {en} } @phdthesis{Eggers2014, author = {Eggers, Ute}, title = {Environmental impacts on white stork (Ciconia ciconia) breeding success}, school = {Universit{\"a}t Potsdam}, pages = {164}, year = {2014}, language = {en} }