Understanding how species respond to environmental conditions can assist with conservation strategies and harvest management, especially in arctic and boreal regions that are experiencing rapid climate change. Although climatic influences on species distributions have been studied, broad‐scale effects of climate on survival are less well known. We examined the interactive effects of meteorological and remotely sensed environmental variables on survival of Dall's sheep (Ovis dalli dalli) lambs and adults by synthesizing radio‐telemetry data across their range. We used data from 9 studies of adult sheep and 2 studies of lambs that were conducted between 1997 and 2012 at sites spanning the species' range in Alaska, USA, and northwestern Canada. We obtained environmental variables throughout the range of Dall's sheep, including the normalized difference vegetation index (NDVI) from optical remote sensing, freeze‐thaw frequency (FTF) from passive microwave remote sensing, and gridded climate variables such as snow water equivalent, temperature, and precipitation. We used Cox proportional hazard regression to investigate the effects of environmental variables recorded during summer, winter, and the previous winter on annual survival rates of Dall's sheep lambs and adults. Summer NDVI was the most influential environmental factor affecting lamb survival, with improved lamb survival occurring in years with a high maximum NDVI. Also, lamb predation by coyotes (Canis latrans) and golden eagles (Aquila chrysaetos) decreased substantially with increasing NDVI. The previous winter FTF had the strongest effect on adult survival, with decreased survival occurring after winters with high FTF. In addition, these remotely sensed environmental factors interacted with meteorological factors to affect survival, such that effects of winter temperature depended on summer NDVI and winter FTF. Warm winters increased lamb survival only when preceded by summers with high NDVI, and warm winters increased adult survival only when winter FTF was low. Thus, potential benefits of climate warming may be counteracted if wintertime freeze‐thaw events markedly increase. Correlations among environmental variables across sites were low, and regional climate cycles such as the Pacific Decadal Oscillation (PDO) had weak effects, indicating substantial local variability in climatic conditions experienced by Dall's sheep across their range. These findings can help managers anticipate how Dall's sheep populations will respond to changes in local environmental conditions. Our results also highlight the utility of multiple remotely sensed environmental conditions for ungulate management, especially passive microwave products that provide valuable information on winter icing events. © 2020 The Wildlife Society.

中文翻译：

---

环境对达尔羊的生存的影响

了解物种如何对环境条件做出反应，可以帮助制定保护策略和进行收获管理，尤其是在气候变化迅速的北极和北方地区。尽管已经研究了气候对物种分布的影响，但是气候对生存的广泛影响却鲜为人知。我们研究了气象和遥感环境变量对Dall绵羊（Ovis dalli dalli），通过综合其范围内的无线电遥测数据，得出羔羊和成年。我们使用了1997年至2012年之间在美国阿拉斯加和加拿大西北部跨物种范围进行的9项成年绵羊研究和2项羔羊研究的数据。我们获得了达尔山羊全范围的环境变量，包括光学遥感的归一化差异植被指数（NDVI），被动微波遥感的冻融频率（FTF）以及网格化的气候变量，例如雪水当量，温度，和降水。我们使用Cox比例风险回归研究了夏季，冬季和前一个冬季记录的环境变量对Dall羊羔和成年羊的年生存率的影响。夏季NDVI是影响羔羊存活率的最有影响力的环境因素，在最大NDVI较高的年份，羔羊存活率有所提高。另外，土狼对羔羊的捕食（犬latrans）和金鹰（天鹰座chrysaetos）随着NDVI的增加而大幅下降。以前的冬季FTF对成年存活率的影响最大，而在FTF高的冬季后存活率下降。此外，这些遥感环境因素与气象因素相互作用，影响生存，因此冬季温度的影响取决于夏季NDVI和冬季FTF。温暖的冬季只有在NDVI高的夏季之后才能提高羔羊的存活率，温暖的冬季只有在冬季FTF较低时才能提高成年羔羊的存活率。因此，如果冬季冻融事件明显增加，则可能抵消气候变暖的潜在好处。各个站点之间的环境变量之间的相关性很低，区域气候周期（如太平洋年代际涛动）的影响较弱，表明达尔山羊在其整个范围内所经历的气候条件存在很大的局部变化。这些发现可以帮助管理人员预测达尔的绵羊种群将如何应对当地环境条件的变化。我们的研究结果还强调了有蹄类动物管理的多种遥感环境条件的实用性，特别是无源微波产品，这些产品可提供有关冬季结冰事件的宝贵信息。©2020野生动物协会。尤其是无源微波产品，可提供有关冬季结冰事件的宝贵信息。©2020野生动物协会。尤其是无源微波产品，可提供有关冬季结冰事件的宝贵信息。©2020野生动物协会。