Swanson Alexandra, Caro Tim, Davies-Mostert Harriet, Mills Michael G L, Macdonald David W, Borner Markus, Masenga Emmanuel, Packer Craig
Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN, 55104, USA.
Serengeti Wildlife Research Institute, Tanzania National Parks, Arusha, Tanzania.
J Anim Ecol. 2014 Nov;83(6):1418-27. doi: 10.1111/1365-2656.12231. Epub 2014 May 13.
Top predators can dramatically suppress populations of smaller predators, with cascading effects throughout communities, and this pressure is often unquestioningly accepted as a constraint on mesopredator populations. In this study, we reassess whether African lions suppress populations of cheetahs and African wild dogs and examine possible mechanisms for coexistence between these species. Using long-term records from Serengeti National Park, we tested 30 years of population data for evidence of mesopredator suppression, and we examined six years of concurrent radio-telemetry data for evidence of large-scale spatial displacement. The Serengeti lion population nearly tripled between 1966 and 1998; during this time, wild dogs declined but cheetah numbers remained largely unchanged. Prior to their local extinction, wild dogs primarily occupied low lion density areas and apparently abandoned the long-term study area as the lion population 'saturated' the region. In contrast, cheetahs mostly utilized areas of high lion density, and the stability of the cheetah population indicates that neither high levels of lion-inflicted mortality nor behavioural avoidance inflict sufficient demographic consequences to translate into population-level effects. Population data from fenced reserves in southern Africa revealed a similar contrast between wild dogs and cheetahs in their ability to coexist with lions. These findings demonstrate differential responses of subordinate species within the same guild and challenge a widespread perception that lions undermine cheetah conservation efforts. Paired with several recent studies that document fine-scale lion-avoidance by cheetahs, this study further highlights fine-scale spatial avoidance as a possible mechanism for mitigating mesopredator suppression.
顶级食肉动物能够显著抑制较小食肉动物的种群数量，从而对整个群落产生连锁反应，这种压力通常被毫无质疑地视为对中型食肉动物种群的一种限制。在本研究中，我们重新评估了非洲狮是否抑制猎豹和非洲野犬的种群数量，并探究了这些物种之间可能的共存机制。利用塞伦盖蒂国家公园的长期记录，我们对30年的种群数据进行了测试，以寻找中型食肉动物受到抑制的证据，并检查了六年的同步无线电遥测数据，以寻找大规模空间位移的证据。在1966年至1998年期间，塞伦盖蒂的狮子种群数量几乎增加了两倍；在此期间，野犬数量减少，但猎豹数量基本保持不变。在当地灭绝之前，野犬主要占据狮子密度较低的区域，并且随着狮子种群使该地区“饱和”，它们显然放弃了长期研究区域。相比之下，猎豹大多利用狮子密度高的区域，而猎豹种群的稳定性表明，无论是狮子造成的高死亡率还是行为回避，都不会造成足够的种群统计学后果，从而转化为种群水平的影响。来自非洲南部围栏保护区的种群数据显示，野犬和猎豹在与狮子共存的能力方面也存在类似的差异。这些发现表明了同一生态位中从属物种的不同反应，并挑战了一种普遍的观念，即狮子会破坏猎豹的保护工作。与最近几项记录猎豹对狮子进行精细尺度回避的研究相结合，本研究进一步强调了精细尺度的空间回避是减轻中型食肉动物抑制的一种可能机制。
