Postnatal growth and age estimation in the broad-tailed bat (Nyctinomops laticaudatus)

We measured forearm length, body mass, and the length of the fourth finger in marked individuals of the broad-tailed bat (Nyctinomops laticaudatus) from birth until the onset of flight at the Palace of the Governor in the Archaeological Zone of Uxmal, Yucatán, Mexico. Growth curves were developed, from which we derived growth rates and age-prediction equations. At birth, the average forearm length, fourth finger length, and body mass represented 45%, 29%, and 31%, respectively, of the corresponding values in postpartum females. These measurements showed a linear growth pattern up to 40 days of age, with average growth rates of 0.44010 mm/day for forearm length, 0.5389 mm/day for fourth finger length, and 0.1415 g/day for body mass, after which the growth rate declined during the flight stage. The equation for estimating age based on forearm length is reliable for measurements ≥37 mm, enabling accurate age estimation for pups aged 1 to 40 days. Flight trials revealed that pups began fluttering with short horizontal movements at 15 days and achieved sustained flight by 40 days of age. The growth rates observed in N. laticaudatus were higher than those reported for many other tropical insectivorous bat species.