Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, 24060, USA.
Department of Natural Resources and Environmental Science, Program in Ecology, Evolution and Conservation Biology, University of Nevada Reno, Mail Stop 186, Reno, Nevada, 89557, USA.
Ecol Appl. 2017 Jan;27(1):168-181. doi: 10.1002/eap.1427.
Weather is a source of environmental variation that can affect population vital rates. However, the influence of weather on individual fitness is spatially heterogeneous and can be driven by other environmental factors, such as habitat composition. Therefore, individuals can experience reduced fitness (e.g., decreased reproductive success) during poor environmental conditions through poor decisions regarding habitat selection. This requires, however, that habitat selection is adaptive and that the organism can correctly interpret the environmental cues to modify habitat use. Greater Sage-Grouse (Centrocercus urophasianus) are an obligate of the sagebrush ecosystems of western North America, relying on sagebrush for food and cover. Greater Sage-Grouse chicks, however, require foods with high nutrient content (i.e., forbs and insects), the abundance of which is both temporally and spatially dynamic and related primarily to water availability. Our goal was to assess whether nest site selection and movements of broods by females reduced the negative effect of drought on offspring survival. As predicted, chick survival was negatively influenced by drought severity. We found that sage-grouse females generally preferred to nest and raise their young in locations where their chicks would experience higher survival. We also found that use of habitats positively associated with chick survival were also positively associated with drought severity, which suggests that females reduced drought impacts on their dependent young by selecting more favorable environments during drought years. Although our findings suggest that female nest site selection and brood movement rates can reduce the negative effects of drought on early offspring survival, the influence of severe drought conditions was not completely mitigated by female behavior, and that drought conditions should be considered a threat to Greater Sage-Grouse population persistence.
天气是环境变化的一个来源，它可以影响种群的生命率。然而，天气对个体健康的影响在空间上是不均匀的，并且可能受到其他环境因素的驱动，例如栖息地组成。因此，个体在环境条件较差的情况下可能会因为对栖息地选择做出了错误的决策而导致健康状况下降（例如繁殖成功率降低）。然而，这需要栖息地选择是适应性的，并且生物体能够正确地解释环境线索以改变栖息地使用。大角羊（Centrocercus urophasianus）是北美西部山艾树生态系统的特有物种，它们依赖山艾树获取食物和庇护。然而，大角羊雏鸟需要高营养含量的食物（即草本植物和昆虫），其丰富度具有时间和空间上的动态变化，主要与水的可获得性有关。我们的目标是评估巢址选择和雌性雏鸟的群体移动是否降低了干旱对后代生存的负面影响。正如预测的那样，雏鸟的存活率受到干旱严重程度的负面影响。我们发现，雌性大角羊通常更喜欢在其雏鸟生存存活率较高的地方筑巢和养育幼鸟。我们还发现，与雏鸟存活率呈正相关的栖息地的利用与干旱严重程度呈正相关，这表明雌性大角羊通过在干旱年份选择更有利的环境来减少干旱对其幼鸟的影响。尽管我们的研究结果表明，雌性的巢址选择和雏鸟的移动速度可以降低干旱对早期后代生存的负面影响，但雌性行为并没有完全减轻严重干旱条件的影响，干旱条件应被视为大角羊种群生存的威胁。
