Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.
Department of Natural Resource Sciences, Macdonald Campus, McGill University, Ste-Anne-de-Bellevue, QC, Canada.
J Anim Ecol. 2020 Sep;89(9):2156-2167. doi: 10.1111/1365-2656.13275. Epub 2020 Jul 19.
Scavenging by vertebrates can have important impacts on food web stability and persistence, and can alter the distribution of nutrients throughout the landscape. However, scavenging communities have been understudied in most regions around the globe, and we lack understanding of the biotic drivers of vertebrate scavenging dynamics. In this paper, we examined how changes in prey density and carrion biomass caused by population cycles of a primary prey species, the snowshoe hare Lepus americanus, influence scavenging communities in the northern boreal forest. We further examined the impact of habitat and temperature on scavenging dynamics. We monitored the persistence time, time until first scavenger, and number of species scavenging experimentally-placed hare carcasses over four consecutive years in the southwestern Yukon. We simultaneously monitored hare density and carrion biomass to examine their influence relative to temperature, habitat, and seasonal effects. For the primary scavengers, we developed species-specific scavenging models to determine variation on the effects of these factors across species, and determine which species may be driving temporal patterns in the entire community. We found that the efficiency of the scavenging community was affected by hare density, with carcass persistence decreasing when snowshoe hare densities declined, mainly due to increased scavenging rates by Canada lynx Lynx canadensis. However, prey density did not influence the number of species scavenging a given carcass, suggesting prey abundance affects carrion recycling but not necessarily the number of connections in the food web. In addition, scavenging rates increased in warmer temperatures, and there were strong seasonal effects on the richness of the vertebrate scavenging community. Our results demonstrate that vertebrate scavenging communities are sensitive to changes in species' demography and environmental change, and that future assessments of food web dynamics should consider links established through scavenging.
脊椎动物的清道夫行为可能对食物网的稳定性和持久性产生重要影响，并能改变营养物质在景观中的分布。然而，在全球大多数地区，清道夫群落都没有得到充分的研究，我们也缺乏对脊椎动物清道夫动态的生物驱动因素的了解。在本文中，我们研究了主要猎物物种雪兔（Lepus americanus）的种群周期引起的猎物密度和腐肉生物量的变化如何影响北方北方森林的清道夫群落。我们进一步研究了栖息地和温度对清道夫动态的影响。我们在育空地区西南部连续四年监测了实验放置的野兔尸体的腐肉时间、首次清道夫出现时间和清道夫物种数量，同时监测了野兔密度和腐肉生物量，以检验它们相对于温度、栖息地和季节变化的影响。对于主要的清道夫，我们开发了特定物种的清道夫模型，以确定这些因素在不同物种中的变化对物种的影响，并确定哪些物种可能是整个群落时间模式的驱动因素。我们发现，清道夫群落的效率受到野兔密度的影响，随着雪兔密度的下降，腐肉的持久性降低，这主要是由于加拿大猞猁（Lynx canadensis）的清道夫率增加所致。然而，猎物密度并不影响一个给定的腐肉被多少种动物捕食，这表明猎物丰度影响腐肉的再循环，但不一定影响食物网中的连接数量。此外，在温暖的温度下，清道夫的速度会增加，而且季节对脊椎动物清道夫群落的丰富度有强烈的影响。我们的研究结果表明，脊椎动物清道夫群落对物种的数量变化和环境变化非常敏感，未来对食物网动态的评估应该考虑通过清道夫建立的联系。
