Habitat associations of bats in a working rangeland landscape

1. Land-use change has resulted in rangeland loss and degradation globally. These changes include conversion of native grasslands for row-crop agriculture as well as degradation of remaining rangeland due to fragmentation and changing disturbance regimes. Understanding how these and other factors influence wildlife use of rangelands is important for conservation and management of wildlife populations. 2. We investigated bat habitat associations in a working rangeland in southeastern North Dakota. We used Petterson d500x acoustic detectors to systematically sample bat activity across the study area on a 1 km point grid. We identified calls using Sonobat autoclassification software. We detected five species using this working rangeland, which included Lasionycteris noctivagans (2,722 detections), Lasiurus cinereus (2,055 detections), Eptesicus fuscus (749 detections), Lasiurus borealis (62 detections) and Myotis lucifugus (1 detection). 3. We developed generalized linear mixed-effects models for the four most frequently detected species based on their ecology. The activity of three bat species increased with higher tree cover. While the scale of selection varied between the four species, all three investigated scales were explanatory for at least one bat species. 4. The broad importance of trees to bats in rangelands may put their conservation needs at odds with those of obligate grassland species. Focusing rangeland bat conservation on areas that were treed prior to European settlement, such as riparian forests, can provide important areas for bat conservation while minimizing negative impacts on grassland species.

1. 全球范围内，土地利用变化已导致牧地（rangeland）流失与退化。此类变化包括将原生草原改造为条播大田作物农田，以及因生境破碎化与扰动格局改变而引发的剩余牧地退化。明晰此类及其他因素如何影响野生动物对牧地的利用，对野生动物种群的保护与管理具有重要意义。
2. 本研究于北达科他州东南部的经营性牧地中开展蝙蝠栖息地关联调查。我们采用Petterson d500x声学探测器，以1公里点位网格的系统抽样方式，对研究区域内的蝙蝠活动进行采样；并借助Sonobat自动分类软件（Sonobat autoclassification software）对蝙蝠鸣叫声进行识别。本次调查共检测到5种栖息于该经营性牧地的蝙蝠，分别为银毛蝠（Lasionycteris noctivagans，2722次检测记录）、灰红蝠（Lasiurus cinereus，2055次检测记录）、大棕蝠（Eptesicus fuscus，749次检测记录）、东方红蝠（Lasiurus borealis，62次检测记录）以及小棕蝠（Myotis lucifugus，1次检测记录）。
3. 本研究基于检测频次最高的4种蝙蝠的生态特征，构建了广义线性混合效应模型（generalized linear mixed-effects models）。结果显示，3种蝙蝠的活动强度随林木覆盖度升高而增强。尽管4个物种的生境选择尺度存在差异，但本次研究涉及的3种尺度均至少对1种蝙蝠的活动具有解释效力。
4. 牧地中林木对蝙蝠的广泛重要性，可能使蝙蝠的保护需求与专性草原物种的保护需求产生冲突。若将牧地蝙蝠保护工作聚焦于欧洲殖民前即存在林木的区域（如河岸林（riparian forests）），则可在尽可能降低对草原物种负面影响的同时，为蝙蝠保护提供关键生境。