Laboratory experiments have provided a wealth of knowledge on antipredator responses and habitat preference in both terrestrial and aquatic salamanders, many of which are difficult to study under natural conditions. However, there remains a dearth of carefully designed experiments to elucidate habitat preferences of aquatic salamanders, many of which are of growing conservation concern. This experimental study evaluated shelter selection of nearly threatened larval eastern hellbender salamanders, Cryptobranchus alleganiensis, in North Carolina. We performed three experiments: 1) ability to burrow under 50% embedded cobble, 2) preference for cobble (~ 120–150 mm) versus gravel (~ 30–60 mm) in an aquarium (ex situ), and 3) preference for cobble over gravel in a natural stream setting (in situ). We found that salamanders (N = 11) showed a preference for cobble (~ 135–137 mm) in both aquarium and in-stream testing environments (87.7% and 88.5% of time, respectively) over gravel and burrowed under cobble in 95% of aquarium and in-stream trials. Moreover, salamanders were unable to burrow under 50% embedded cobble and were actively moving 38.1% of the time in our burrowing experiment, highlighting the potential for larvae to remain exposed to predators if streams contain buried substrate. Our study provides preliminary evidence on the behavior of these cryptic larval salamanders, suggesting that they prefer cobble substrate and are unable to utilize embedded cobble. These findings have management implications for juveniles of this species, particularly in areas where prolonged sedimentation has the potential to make cobble unavailable for larvae.

中文翻译：

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东部黑ender幼sal（Cryptobranchus alleganiensis）栖息地偏好的观察。

实验室实验为陆生和水生sal提供了有关反捕食者反应和生境偏好的丰富知识，其中许多在自然条件下很难研究。但是，仍然缺乏精心设计的实验来阐明水生sal的栖息地偏好，其中许多都越来越引起人们的关注。这项实验研究评估了濒临灭绝的幼体东部地狱蜥蜴sal（Cryptobranchus alleganiensis）的避难所选择，在北卡罗来纳州。我们进行了三个实验：1）在50％的嵌入式卵石下挖洞的能力； 2）在水族馆（异地）中卵石（〜120–150 mm）与砾石（〜30–60 mm）的偏爱，以及3）对卵石的偏爱。在自然流环境中（原位）在砾石上进行卵石修补。我们发现，蝾螈（ñ = 11）在水族和流内测试环境（分别为87.7％和88.5％的时间）中均显示卵石（〜135-137 mm）优先于砾石，并且在95％的水族和流中在卵石下挖洞审判。此外，sal在50％的嵌入式卵石下无法挖洞，并且在我们的挖洞实验中活跃地移动了38.1％的时间，这突显了如果溪流中含有被掩埋的底物，幼虫仍可能暴露于捕食者的可能性。我们的研究为这些隐性幼虫sal的行为提供了初步证据，表明它们更喜欢卵石基质，并且无法利用嵌入式卵石。这些发现对该物种的幼鱼有管理意义，特别是在长时间的沉积可能使幼虫无法获得卵石的地区。