Research on use of foraging patches has focused on why herbivores visit or quit patches, yet little is known about visits to patches over time. Food quality, as reflected by higher nutritional quality and lower plant defenses, and physical patch characteristics, which offer protection from predators and weather, affect patch use and hence should influence their revisitation. Due to the potentially high costs of moving between patches, fragmented habitats are predicted to complicate foraging decisions of many animals. We aimed to determine how food quality, shelter availability and habitat fragmentation influence tree reuse by a specialist folivore, the koala, in a fragmented agricultural landscape. We GPS-tracked 23 koalas in northern New South Wales, Australia and collated number of revisits, average residence time, and average time-to-return to each tree. We measured tree characteristics including food quality (foliar nitrogen and toxic formylated phloroglucinol compounds, FPCs concentrations), tree size, and tree connectedness. We also modeled the costs of locomotion between trees. Koalas re-visited isolated trees with high leaf nitrogen disproportionately often. They spent longer time in trees with high leaf nitrogen, and in large trees used for shelter. They took longer to return to trees with low leaf nitrogen. Tree connectivity reduced travel costs between patches, being either individual or groups of trees. FPC levels had no detectable effect on patch revisitation. We conclude that food quality and shelter drive koala tree re-visits. Scattered, isolated trees with nutrient-rich leaves are valuable resource patches for koalas despite movement costs to reach them.

中文翻译：

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斑块质量和栖息地破碎化塑造了专业食叶动物的觅食模式


关于使用觅食斑块的研究主要集中于食草动物访问或退出斑块的原因，但对于随着时间的推移对斑块的访问却知之甚少。食品质量（如较高的营养质量和较低的植物防御能力）以及物理斑块特征（可提供针对捕食者和天气的保护）会影响斑块的使用，因此应影响其重新审视。由于在斑块之间移动的成本可能很高，预计破碎的栖息地将使许多动物的觅食决策变得复杂。我们的目的是确定食品质量、庇护所可用性和栖息地破碎化如何影响专业食叶动物考拉在破碎的农业景观中对树木的再利用。我们通过 GPS 追踪了澳大利亚新南威尔士州北部的 23 只考拉，并整理了重访次数、平均停留时间以及返回每棵树的平均时间。我们测量了树木特征，包括食物质量（叶面氮和有毒甲酰化间苯三酚化合物、FPC 浓度）、树木大小和树木连通性。我们还对树木之间的移动成本进行了建模。考拉不成比例地频繁地重新访问叶子含氮量高的孤立树木。它们在叶氮含量高的树木和用于遮蔽的大树上停留的时间更长。他们需要更长的时间才能回到叶氮含量低的树木。树木连通性降低了斑块之间的旅行成本，无论是单个树木还是成群的树木。 FPC 水平对斑块重访没有可检测到的影响。我们得出的结论是，食物质量和庇护所推动了考拉树的再次出现。分散的、孤立的、叶子营养丰富的树木对于考拉来说是宝贵的资源斑块，尽管到达它们的移动成本很高。