Data from: The dynamics of tent-roosts in the palm Sabal mauritiiformis and their use by bats in a montane dry forest

Tent-making bats modify leaves to build refuges. Leaf modification involves energetic and defense costs that should be balanced by the benefits of tent-roosting. The alteration of the leaf’s vascular system reduces the tent’s life expectancy, so to obtain a benefit bats are expected to use tents regularly as long as they are functional and not modify more leaves than necessary. Over two years we documented the dynamics of tent construction and use by Uroderma convexum and other bat species in the palm Sabal mauritiiformis in a Colombian transitional dry forest. We also assessed tent condition and compared it to nonmodified leaves of approximately the same age in focal palms. Probability of tent use by U. convexum varied between 57 percent during a reproductive period and 4 percent outside of this period. Bats cut the main vein of folioles, partially affecting water transport in the leaf. However, there were no differences between tents and nonmodified leaves in deterioration scores or deterioration rates over one year. During two years, 48 tents were lost for different causes, but this loss was balanced by the construction of 51 new tents. Thus, bats maintained an excess of usable tents. Palm leaves are long-lived and seem preadapted to sustain damage and remain viable, particularly in species growing in dry environments. We present several hypotheses to explain the advantage of maintaining a tent surplus.

筑帐蝠（Tent-making bats）可通过改造叶片构建栖息庇护所。叶片改造过程需付出能量投入与防御成本，该成本应与帐栖行为带来的收益达成平衡。对叶片维管系统的破坏会缩短这类“帐篷”的预期寿命，因此，为获得收益，蝙蝠应在帐篷仍具备使用功能时定期利用，且不会过度改造叶片。本研究历时两年，在哥伦比亚过渡性干旱森林中，对凸面叶口蝠（Uroderma convexum）及其他蝙蝠物种利用萨巴尔棕榈（Sabal mauritiiformis）叶片构筑和使用栖息帐篷的动态过程进行了系统记录。同时，我们评估了这些栖息帐篷的状态，并将其与目标棕榈上同龄未改造叶片进行了对照分析。凸面叶口蝠使用栖息帐篷的概率在繁殖期为57%，非繁殖期仅为4%。蝙蝠会切割小叶的主脉，此举会部分干扰叶片内的水分运输。然而，栖息帐篷与未改造叶片在一年内的劣化评分及劣化速率均无显著差异。两年间共有48个栖息帐篷因不同原因受损丢失，但该损失通过新建的51个新帐篷得到了补充，因此蝙蝠维持了一定量的可用帐篷余量。棕榈叶片寿命较长，似乎预先适应了承受损伤并保持生理活力，这一特性在干旱环境中生长的物种中尤为明显。最后，我们提出多项假说，用以解释维持帐篷余量的进化优势。