The demographic contributions of connectivity versus local dynamics to population growth of an endangered bird,Journal of Animal Ecology

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The demographic contributions of connectivity versus local dynamics to population growth of an endangered bird
Journal of Animal Ecology ( IF 3.5 ) Pub Date : 2021-01-15 , DOI: 10.1111/1365-2656.13387
Brian E. Reichert ₁ , Robert J. Fletcher ₁ , Wiley M. Kitchens ₁

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Conservation and management increasingly focus on connectivity, because connectivity driven by variation in immigration rates across landscapes is thought to be crucial for maintaining local population and metapopulation persistence. Yet, efforts to quantify the relative role of immigration on population growth across the entire range of species and over time have been lacking. We assessed whether immigration limited local and range-wide population growth of the endangered snail kite (Rostrhamus sociabilis) in Florida, USA, over 18 years using multi-state, reverse-time modeling that accounts for imperfect detection of individuals and unobservable states. Demographic contributions of immigration varied depending on the dynamics and geographic position of the local populations, were scale-dependent, and changed over time. By comparing the relative contributions of immigration versus local demography for periods of significant change in local abundance, we found empirical evidence for a disproportionately large role of immigration in facilitating population growth of a centrally-located population-a connectivity 'hub'. The importance of connectivity changed depending of the spatial scale considered, such that immigration was a more important driver of population growth at small versus large spatial scales. Furthermore, the contribution of immigration was much greater during time periods when local population size was small, emphasizing abundance-dependent rescue effects. Our findings suggest that efforts aimed at improving local breeding habitat will likely be most effective at increasing snail kite population growth. More broadly, our results provide much needed information on the role of connectivity for population growth, suggesting that connectivity conservation may have the greatest benefits when efforts focus on centrally located habitat patches and small populations. Furthermore, our results highlight that connectivity is highly dynamic over time and that interpreting the effects of connectivity at local scales may not transfer to region-wide dynamics.

中文翻译：

连通性与当地动态对濒危鸟类种群增长的人口统计贡献

保护和管理越来越关注连通性，因为由跨景观的移民率变化驱动的连通性被认为对于维持当地人口和综合种群的持久性至关重要。然而，一直缺乏量化移民对整个物种范围内和随着时间的推移人口增长的相对作用的努力。我们使用多状态、逆时模型评估了移民是否限制了美国佛罗里达州濒危蜗牛风筝 (Rostrhamus sociabilis) 在 18 年中的局部和范围内人口增长，该模型解释了对个体和不可观察状态的不完美检测。移民的人口贡献因当地人口的动态和地理位置而异，与规模有关，并随时间变化。通过比较移民与当地人口在当地丰度显着变化时期的相对贡献，我们发现了经验证据，证明移民在促进位于中心位置的人口（连通性“枢纽”）的人口增长方面发挥了不成比例的巨大作用。连通性的重要性取决于所考虑的空间尺度，因此移民是小空间尺度与大空间尺度人口增长的更重要驱动因素。此外，在当地人口规模较小的时期，移民的贡献要大得多，强调了丰度依赖的救援效果。我们的研究结果表明，旨在改善当地繁殖栖息地的努力可能对增加蜗牛风筝种群增长最有效。更广泛地，我们的结果提供了关于连通性对人口增长的作用的急需信息，表明当努力集中在位于中心的栖息地斑块和小种群时，连通性保护可能会带来最大的好处。此外，我们的结果强调，连通性随着时间的推移是高度动态的，并且在局部尺度上解释连通性的影响可能不会转移到区域范围的动态。

更新日期：2021-01-15

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