Data from: Indirect food web interactions mediated by rodent cycles: relative roles of lemmings and voles

Production cycles in birds are proposed as prime cases of indirect interactions in food webs. They are thought to be driven by predators switching from rodents to bird nests in the crash phase of rodent population cycles. Although rodent cycles are geographically widespread and found in different rodent taxa, bird production cycles appear to be most profound in the high Arctic where lemmings dominate. We hypothesized that this may be due to arctic lemmings inducing stronger predator responses than boreal voles. We tested this hypothesis by estimating predation rates in dummy bird nests during a rodent cycle in low arctic tundra. Here the rodent community consists of a spatially variable mix of one lemming (Lemmus lemmus) and two vole species (Myodes rufocanus and Microtus oeconomus) with similar abundances. In consistence with our hypothesis, lemming peak abundances predicted well crash-phase nest predation rates, whereas the vole abundances had no predictive ability. Corvids were found to be the most important nest predators. Lemmings appear to be accessible to the whole predator community which makes them particularly powerful drivers of food web dynamics.鸟类繁殖周期被认为是食物网间接相互作用的典型案例。这类周期被认为是由啮齿动物种群周期崩溃阶段中，捕食者从捕食啮齿动物转向捕食鸟巢所驱动的。尽管啮齿动物周期在地理上分布广泛，且存在于不同的啮齿动物类群中，但鸟类繁殖周期的影响在以旅鼠为主的高北极地区最为显著。我们提出假设，这可能是因为北极旅鼠相较于北方田鼠，能引发更强的捕食者响应。我们通过在低北极苔原的啮齿动物周期期间，估算人工鸟巢的捕食率来验证这一假设。该区域的啮齿动物群落由空间分布不均的1种旅鼠（Lemmus lemmus）和2种田鼠（Myodes rufocanus与Microtus oeconomus）组成，且三者种群丰度相近。与我们的假设一致，旅鼠的种群峰值能够很好地预测崩溃期的鸟巢捕食率，而田鼠的种群丰度则无预测能力。研究发现鸦科动物是最为关键的鸟巢捕食者。旅鼠似乎可被整个捕食者群落所利用，这使其成为驱动食物网动态的格外强有力的驱动因子。