Hellbenders Cryptobranchus alleganiensis are critically imperiled amphibians throughout the eastern USA. Rock-lifting is widely used to monitor hellbenders but can severely disturb habitat. We asked whether artificial shelter occupancy (the proportion of occupied shelters in an array) would function as a proxy for hellbender abundance and thereby serve as a viable alternative to rock-lifting. We hypothesized that shelter occupancy would vary spatially in response to hellbender density, natural shelter density, or both, and would vary temporally with hellbender seasonal activity patterns and time since shelter deployment. We established shelter arrays (n = 30 shelters each) in 6 stream reaches and monitored them monthly for up to 2 yr. We used Bayesian mixed logistic regression and model ranking criteria to assess support for hypotheses concerning drivers of shelter occupancy. In all reaches, shelter occupancy was highest from June–August each year and was higher in Year 2 relative to Year 1. Our best-supported model indicated that the extent of boulder and bedrock (hereafter, natural shelter) in a reach mediated the relationship between hellbender abundance and shelter occupancy. More explicitly, shelter occupancy was positively correlated with abundance when natural shelter covered <20% of a reach, but uncorrelated with abundance when natural shelter was more abundant. While shelter occupancy should not be used to infer variation in hellbender relative abundance when substrate composition varies among reaches, we showed that artificial shelters can function as valuable monitoring tools when reaches meet certain criteria, though regular shelter maintenance is critical.

中文翻译：

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评估人工庇护所阵列作为地狱弯曲者 Cryptobranchus alleganiensis 的微创监测工具

Hellbenders Cryptobranchus alleganiensis 是整个美国东部濒临灭绝的两栖动物。岩石提升被广泛用于监测地狱弯曲者，但会严重扰乱栖息地。我们询问人工庇护所的占用率（阵列中被占用的庇护所的比例）是否可以作为地狱弯曲者丰度的代表，从而作为一种可行的岩石提升替代方案。我们假设避难所占用率会因地狱使者密度、自然避难所密度或两者而在空间上发生变化，并且会随地狱使者季节性活动模式和避难所部署后的时间而随时间变化。我们在 6 个河段建立了庇护所阵列（每个 n = 30 个庇护所）并每月对其进行监测长达 2 年。我们使用贝叶斯混合逻辑回归和模型排名标准来评估对有关庇护所占用驱动因素的假设的支持。在所有河段，每年 6 月至 8 月的庇护所入住率最高，相对于第 1 年，第 2 年更高。我们最受支持的模型表明，河段中的巨石和基岩（以下称为自然庇护所）的范围调节了这种关系在地狱使者丰度和住所入住率之间。更明确地说，当自然庇护所覆盖范围小于 20% 时，庇护所占用率与丰度呈正相关，但当自然庇护所更丰富时，庇护所占用率与丰度不相关。当底物组成因河段而异时，不应使用住所占用率来推断地狱犬相对丰度的变化，