The risk of nest depredation is influenced by numerous factors, including predator density, environmental conditions of the nesting landscape, and nesting behaviors of mothers. Many reptiles choose nest microhabitats that facilitate embryonic development, but little is known about how the risk of nest depredation in different habitats influences egg survival and nesting behavior. To address this knowledge gap, we quantified predator–prey relationships between square-back marsh crabs ( Armases cinereum ) and eggs of the brown anole lizard ( Anolis sagrei ). Our experiments aimed to answer the following questions: (1) are marsh crabs a predator of brown anole eggs, (2) does egg depredation differ among microhabitat types, and (3) how does crab density affect egg survival? We placed viable eggs in three different microhabitats used by nesting females (open area, palm frond, leaf litter), and manipulated the placement of the eggs as either buried or not buried. We also manipulated crab density in a field experiment. Our experiments confirmed square-back marsh crabs as egg predators, and eggs in the leaf litter or eggs buried were the least likely to be depredated. Additionally, eggs in leaf litter and under palm fronds escaped depredation longer than those in the open. Increased crab density also raised the risk of depredation for eggs placed under palm fronds or in open habitats. These results suggest that selection of nest sites by female brown anoles can influence offspring survival in the presence of marsh crabs, and the importance of nest site microhabitat choice may vary with predator density.

中文翻译：

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在无脊椎动物巢穴捕食者存在的情况下，蜥蜴卵的存活率因微生境而异

巢穴被掠夺的风险受到多种因素的影响，包括捕食者密度、筑巢景观的环境条件以及母亲的筑巢行为。许多爬行动物选择促进胚胎发育的巢穴微栖息地，但对不同栖息地的巢穴掠夺风险如何影响卵存活和筑巢行为知之甚少。为了解决这一知识鸿沟，我们量化了方背沼泽蟹 (Armases cinereum) 和褐蜥蜴 (Anolis sagrei) 卵之间的捕食者-猎物关系。我们的实验旨在回答以下问题：(1) 沼泽蟹是否是棕色 anole 卵的捕食者，(2) 不同微生境类型对卵的掠夺是否不同，(3) 螃蟹密度如何影响卵的存活率？我们将有活力的卵放置在筑巢雌性使用的三种不同的微生境中（开放区域、棕榈叶、落叶），并操纵卵的位置，无论是埋藏还是不埋藏。我们还在现场实验中操纵了螃蟹密度。我们的实验证实方背沼泽蟹是卵捕食者，落叶中的卵或埋藏的卵最不可能被掠夺。此外，落叶层和棕榈叶下的卵比露天的卵逃脱捕食的时间更长。螃蟹密度的增加也增加了放置在棕榈叶下或开放栖息地中的卵被掠夺的风险。这些结果表明，雌性棕色 anoles 对巢址的选择会影响在沼泽蟹存在下的后代生存，