Tree cavities are important denning sites for many arboreal mammals. Knowledge of cavity requirements of individual species, as well as potential den overlap among species, is integral to their conservation. In Australia's tropical savannas, development of tree cavities is enhanced by high termite activity, and, conversely, reduced by frequent fires. However, it is poorly understood how the availability of tree cavities in the tropical savannas impacts tree cavity use and selection by cavity-dependent fauna. There has been a severe decline among arboreal mammal species in northern Australia over recent decades. Investigation of their cavity requirements may illuminate why these species have declined drastically in some areas but are persisting in others. Here we examined this issue in three species of arboreal mammals (Trichosurus vulpecula, Mesembriomys gouldii, Conilurus penicillatus) on Melville Island, northern Australia. We radiotracked individuals to their den sites to evaluate whether the species differ in their den tree and tree-cavity selection. The strongest influence on den tree selection was the presence of large cavities (> 10 cm entrance diameter), with all three species using larger cavities most frequently. Conilurus penicillatus, the smallest species, differed the most from the other species: it frequently was found in smaller, dead trees and its den sites were closer to the ground, including in hollow logs. The two larger species had broader den tree use, using larger live trees and dens higher up in the canopy. Dens of C. penicillatus are likely to be more susceptible to predation and destruction by high-intensity savanna fires. This may have contributed to this species' rapid decline, both on Melville Island and on the mainland. However, the apparent preference for larger tree cavities by all three arboreal species is concerning due to the limited availability of large trees across Australian savannas, which are subject to frequent, high-intensity fires.

中文翻译：

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澳大利亚热带稀树草原中三种树栖哺乳动物的重叠巢穴树选择

树洞是许多树栖哺乳动物的重要栖息地。了解单个物种的空洞要求以及物种之间潜在的巢穴重叠是它们保护不可或缺的一部分。在澳大利亚的热带稀树草原，高白蚁活动促进了树洞的发育，相反，频繁的火灾会减少树洞的发育。然而，人们对热带稀树草原中树洞的可用性如何影响依赖树洞的动物群对树洞的使用和选择知之甚少。近几十年来，澳大利亚北部的树栖哺乳动物物种数量急剧下降。对它们的腔体要求的调查可能会阐明为什么这些物种在某些地区急剧下降，但在其他地区仍然存在。在这里，我们在三种树栖哺乳动物（Trichosurus vulpecula、Mesembriomys gouldii，Conilurus penicillatus）在澳大利亚北部的梅尔维尔岛。我们对个体进行了无线电追踪，以评估它们的巢穴树和树洞选择是否不同。对巢树选择的最大影响是存在大洞（> 10 厘米入口直径），所有三个物种最常使用较大的洞。Conilurus penicillatus 是最小的物种，与其他物种的区别最大：它经常出现在较小的枯树中，其巢穴更靠近地面，包括空心原木。两个较大的物种有更广泛的树穴使用，使用更大的活树和树冠更高的巢穴。C. penicillatus 的巢穴可能更容易受到高强度热带稀树草原火灾的捕食和破坏。这可能导致该物种在梅尔维尔岛和大陆迅速减少。然而，由于澳大利亚热带稀树草原上的大树数量有限，而且经常遭受高强度火灾，因此所有三种树栖物种明显偏爱较大的树洞是令人担忧的。