Winter Roost Selection of Lasiurine Tree Bats in a Pyric Landscape

Day-roost selection by tree bats during winter and their response to dormant season fires is poorly known throughout much of the southeastern United States. In the winter of 2019, we mist-netted and affixed radio-transmitters to 16 Lasiurine bats, primarily Seminole bats (Lasiurus seminolus) at Camp Blanding Joint Training Center in northern Florida. We then located day-roost sites to generally describe roost attributes. For five Seminole bats, one eastern red bat (Lasiurus borealis), and one hoary bat (Lasiurus cinereus), we applied prescribed burns in the roost area to observe bat response. Generally, Seminole bats selected day-roosts in mesic forest stands with high mean fire return intervals. At the roost tree scale , Seminole day-roosts tended to be larger, taller and in higher canopy dominance classes than surrounding trees. Seminole bats day-roosted in longleaf (Pinus palustris), slash (Pinus elliotii) and loblolly pine (Pinus taeda) more than expected based on availability, whereas sweetbay (Magnolia virginiana), water oak (Quercus nigra) and turkey oak (Quercus laevis), were roosted in less than expected based on availability. Of the seven roosts subjected to prescribed burns, only one male Seminole bat and one male eastern red bat evacuated the day-roost during or after burning. In both cases, these bats had day-roosted at heights lower and in trees smaller than the majority of other day-roosts observed during our study. Although fires historically were predominantly growing season, they now occur in the dormant season in this part of the Coastal Plain, our results possibly suggest Seminole bats choose winter day-roosts that both maximize solar exposure and minimize risks associated with fire. Nonetheless, at least for Seminole bats, because selected day-roosts largely were fire-dependent or tolerant species, application of fire does need to periodically occur to promote recruitment and retention of these tree species.

在北美东南部大部分地区，关于树栖蝙蝠在冬季选择日间栖息地及其对休眠季节火灾的反应知之甚少。在2019年冬季，我们在佛罗里达州北部的Camp Blanding联合训练中心对16只拉斯伊乌蝙蝠（以塞米诺尔蝙蝠（Lasiurus seminolus）为主）进行了迷网捕捉，并为其佩戴了无线电发射器。随后，我们确定了日间栖息地位置，以概括性地描述栖息地属性。对于5只塞米诺尔蝙蝠、1只东方红蝙蝠（Lasiurus borealis）和1只银色蝙蝠（Lasiurus cinereus），我们在栖息地附近实施了规定燃烧，以观察蝙蝠的反应。总体而言，塞米诺尔蝙蝠倾向于选择具有较高平均火灾回归间隔的湿润森林群落的日间栖息地。在栖息地树木的尺度上，塞米诺尔蝙蝠的日间栖息地往往比周围树木更大、更高，且在冠层优势等级上更高。基于可用性，塞米诺尔蝙蝠在长叶松（Pinus palustris）、平地松（Pinus elliotii）和火炬松（Pinus taeda）中选择了比预期更多的日间栖息地，而甜楝（Magnolia virginiana）、水青冈（Quercus nigra）和 turkey 楝（Quercus laevis）的栖息地则比预期少。在遭受规定燃烧的7个栖息地中，只有一只雄性塞米诺尔蝙蝠和一只雄性东方红蝙蝠在燃烧期间或之后撤离了日间栖息地。在这两种情况下，这些蝙蝠的日间栖息地高度低于其他观察到的日间栖息地，且树木较小。尽管历史上火灾主要发生在生长季节，但现在这部分海岸平原地区在休眠季节也会发生火灾，我们的结果可能表明塞米诺尔蝙蝠选择冬季日间栖息地，既能最大化太阳能的照射，又能最小化与火灾相关的风险。然而，至少对于塞米诺尔蝙蝠而言，由于选定的日间栖息地主要是对火灾依赖或耐受的物种，因此定期实施火灾对于促进这些树种的招募和保留是必要的。