CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China.
PLoS One. 2011;6(9):e24449. doi: 10.1371/journal.pone.0024449. Epub 2011 Sep 7.
Environmental factors that affect spatiotemporal distribution patterns of animals usually include resource availability, temperature, and the risk of predation. However, they do not explain the counterintuitive preference of high elevation range in winter by the black-and-white snub-nosed monkey (Rhinopithecus bieti). We asked whether variation of sunshine along with elevations is the key driving force. To test this hypothesis, we conducted field surveys to demonstrate that there was a statistically significant pattern of high elevation use during winter. We then asked whether this pattern can be explained by certain environmental factors, namely temperature, sunshine duration and solar radiation. Finally, we concluded with a possible ecological mechanism for this pattern. In this study, we employed GIS technology to quantify solar radiation and sunshine duration across the monkey's range. Our results showed that: 1) R. bieti used the high altitude range between 4100-4400 m in winter although the yearly home range spanned from 3500-4500 m; 2) both solar radiation and sunshine duration increased with elevation while temperature decreased with elevation; 3) within the winter range, the use of range was significantly correlated with solar radiation and sunshine duration; 4) monkeys moved to the areas with high solar radiation and duration following a snowfall, where the snow melts faster and food is exposed earlier. We concluded that sunshine was the main factor that influences selection of high elevation habitat for R. bieti in winter. Since some other endotherms in the area exhibit similar winter distributional patterns, we developed a sunshine hypothesis to explain this phenomenon. In addition, our work also represented a new method of integrating GIS models into traditional field ecology research to study spatiotemporal distribution pattern of wildlife. We suggest that further theoretical and empirical studies are necessary for better understanding of sunshine influence on wildlife range use.
影响动物时空分布格局的环境因素通常包括资源可用性、温度和被捕食的风险。然而，这些因素并不能解释黑白仰鼻猴（Rhinopithecus bieti）在冬季偏爱高海拔地区的反直觉现象。我们想知道沿海拔高度变化的阳光是否是关键驱动力。为了验证这一假设，我们进行了实地调查，结果表明冬季高海拔地区的使用存在显著的统计模式。然后，我们询问这种模式是否可以用某些环境因素来解释，即温度、日照时间和太阳辐射。最后，我们对这种模式提出了一个可能的生态机制。在这项研究中，我们利用 GIS 技术来量化猴子活动范围内的太阳辐射和日照时间。结果表明：1）尽管 R. bieti 的年活动范围在 3500-4500 米之间，但它在冬季会使用海拔 4100-4400 米的高海拔地区；2）太阳辐射和日照时间随海拔升高而增加，而温度随海拔升高而降低；3）在冬季活动范围内，猴子对高海拔地区的使用与太阳辐射和日照时间显著相关；4）猴子会在一场雪后迁移到高太阳辐射和长日照时间的地区，因为那里的雪融化得更快，食物也会更早暴露。我们得出的结论是，阳光是影响 R. bieti 在冬季选择高海拔栖息地的主要因素。由于该地区的其他一些恒温动物也表现出类似的冬季分布模式，我们提出了一个阳光假说来解释这一现象。此外，我们的工作还代表了将 GIS 模型集成到传统野外生态学研究中以研究野生动物时空分布模式的一种新方法。我们建议进一步进行理论和实证研究，以更好地了解阳光对野生动物活动范围的影响。
