@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}
}
@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}
}