Data from: Marine subsidies change short-term foraging activity and habitat utilization of terrestrial lizards

Resource pulses are brief periods of unusually high resource abundance. While population and community responses to resource pulses have been relatively well-studied, how individual consumers respond to resource pulses has received less attention. Local consumers are the first to respond to a resource pulse, and the form and timing of individual responses may influence how the effects of the pulse are transmitted throughout the community. Previous studies in Bahamian food webs have shown that detritivores associated with pulses of seaweed wrack provide an alternative prey source for lizards. When seaweed is abundant, lizards (Anolis sagrei) shift to consuming more marine-derived prey and increase in density, which has important consequences for other components of the food web. We hypothesized that the diet shift requires individuals to alter their habitat use and foraging activity, and that such responses may happen very rapidly. In this study, we investigated the immediate responses of lizards to an experimental seaweed pulse. We added seaweed to 5 treatment plots for comparison with 5 control plots. Immediately after seaweed addition, lizards decreased average perch height and increased movement rate, but these effects persisted for only two days. To explore the short-term nature of the response, we used our field data to parametrize heuristic Markov chain models of perch height as a function of foraging state. These models suggest a “Synchronized-satiation Hypothesis,” whereby lizards respond synchronously and feed quickly to satiation in the presence of subsidy (causing an initial decrease in average perch height) and then return to the relative safety of higher perches. We suggest that the immediate responses of individual consumers to resource-pulse events can provide insight into the mechanisms by which these consumers ultimately influence community-level processes.

资源脉冲（resource pulse）是指资源丰度异常升高的短暂时段。尽管学界针对种群与群落对资源脉冲的响应已有较为充分的研究，但单个消费者个体如何响应资源脉冲的相关探讨仍相对不足。本地消费者是最先响应资源脉冲的类群，其响应的形式与时机，可能会影响脉冲效应在整个群落中的传递路径。此前针对巴哈马食物网的研究表明，与海藻枯落物脉冲相关的食腐动物，可作为蜥蜴的替代猎物来源。当海藻资源充足时，萨氏安乐蜥（Anolis sagrei）会转向更多捕食海洋来源的猎物，且种群密度有所上升，这对食物网的其他组分具有重要影响。我们提出假说：这种食性转变需要个体改变其栖息地利用模式与觅食行为，且此类响应可能快速发生。本研究针对实验性海藻脉冲，探究了蜥蜴的即时响应。我们在5个处理样地中添加海藻，并设置5个对照样地作为对照。海藻添加后即刻，蜥蜴的平均栖息高度下降、移动速率上升，但此类效应仅持续了两天。为探究响应的短期性特征，我们利用野外数据，以觅食状态为自变量，对栖息高度构建启发式马尔可夫链模型（Markov chain model）并完成参数化。此类模型揭示了“同步饱食假说（Synchronized-satiation Hypothesis）”：当存在外源营养补贴时，蜥蜴会同步响应并快速取食至饱食状态（此过程会导致平均栖息高度初始下降），随后返回至栖息高度更高的相对安全区域。我们认为，单个消费者个体对资源脉冲事件的即时响应，可为揭示这类消费者最终如何影响群落级过程的机制提供重要视角。