Behavioral observations of Molossus nigricans in a Neotropical city: a contribution toward understanding its urban tolerance

The family Molossidae includes several species of bats that thrive in tropical and subtropical cities of the world. It has been suggested that the remarkable tolerance of some molossid species to urban life might partially result from a suite of behavioral preadaptations. In this study, we described some aspects of the roosting, social, vocal, and foraging behavior of one of these species, Molossus nigricans Miller, 1902, in the tropical city of Villahermosa, in southeastern Mexico. We described roosting attributes and colony size in 54 roosts of M. nigricans between 2016 and 2018. In a subsample of roosts, we registered emergence and return times throughout the night, described colony composition, and recorded vocalizations using a full-spectrum ultrasonic detector. We found that M. nigricans exhibits high plasticity in its roosting behavior, occupying both natural and anthropogenic structures with narrow gaps and cracks. Their social structure appears to be flexible, and their colonies are variable in size, allowing them to exploit a wide variety of roosts. Their high foraging efficiency, tolerance to artificial light, and its remarkable vocal plasticity seem to be other elements that may help us to better understand the success of M. nigricans in tropical urban environments.