North American Bat Species Research Articles

Metagenomic Analysis of the Viromes of Three North American Bat Species: Viral Diversity among Different Bat Species That Share a Common Habitat

Metagenomic Analysis of the Viromes of Three North American Bat Species: Viral Diversity among Different Bat Species That Share a Common Habitat

The Perils of Picky Eating: Dietary Breadth Is Related to Extinction Risk in Insectivorous Bats

Several recent papers evaluate the relationship between ecological characteristics and extinction risk in bats. These studies report that extinction risk is negatively related to geographic range size and positively related to habitat specialization. Here, we evaluate the hypothesis that extinction risk is also related to dietary specialization in insectivorous vespertilionid bats using both traditional and phylogenetically-controlled analysis of variance. We collected dietary data and The World Conservation Union (IUCN) rankings for 44 Australian, European, and North American bat species. Our results indicate that species of conservation concern (IUCN ranking near threatened or above) are more likely to have a specialized diet than are species of least concern. Additional analyses show that dietary breadth is not correlated to geographic range size or wing morphology, characteristics previously found to correlate with extinction risk. Therefore, there is likely a direct relationship between dietary specialization and extinction risk; however, the large variation in dietary breadth within species of least concern suggests that diet alone cannot explain extinction risk. Our results may have important implications for the development of predictive models of extinction risk and for the assignment of extinction risk to insectivorous bat species. Similar analyses should be conducted on additional bat families to assess the generality of this relationship between niche breadth and extinction risk.

A Comparative Analysis of Specialization and Extinction Risk in Temperate‐Zone Bats

Abstract: Identifying the factors that influence the extinction risk of animals is essential in conservation biology because they help identify endangered species and provide the basis for their preservation. We present a comparative study that uses data from the literature on the diet and morphological specialization of European and North American bat species to investigate the effect of specialization on extinction risk. We focused on bats because many species are endangered and their high ecological diversity makes them a good model system for our purpose. After correcting for phylogenetic inertia, we compared the influence of dietary niche breadth as a measure of food specialization and of wing morphology as a measure of foraging strategy, habitat adaptation, and migratory ability on the vulnerability of 35 insectivorous bat species. Our results do not support the hypothesis that a narrow dietary niche breadth is related to high extinction risk. Instead they suggest that habitat specialization, which is reflected in wing morphology, influences the extinction risk of bats. Our study shows that an initial risk assessment in temperate‐zone bats could be based on data of wing morphology but not on dietary data obtained from fecal analyses.

Pre-Weaning Mortality in a Florida Maternity Roost of Myotis austroriparius and Tadarida brasiliensis

The roost environment is a factor determining the survival and mortality rates in newborn bats. We compared mortality in two species of bats that shared a common roost but that differed in developmental strategies. The precocial species, Tadarida brasiliensis, appeared to exhibit less preweaning mortality than did the altricial species, Myotis austroriparius. Pre-weaning mortality in M. austroriparius was most pronounced shortly after birth. Many North American bat species produce a single precocial offspring each year, a demographic response related to the brevity of the season during which offspring can be produced and reared (Tuttle and Stevenson, 1982), restricted food supply (Humphrey, 1975), or aerodynamic constraints (Myers, 1978). The southeastern brown bat M. austroriparius however, commonly produces altricial twins (Foster et al., 1978). Central Florida populations of M. austroriparius do not hibernate and are therefore exposed to in-flight mortality factors over a larger portion of the year than other temperate Myotis. Maternity roosts of M. a. austroriparius are generally found in limestone caves over water where pre-weaning mortality is significant because females cannot retrieve fallen young from the water (Rice, 1957). Thus, twinning is thought to be an adaptive response to a high annual mortality of M. austroriparius (Foster et al., 1978). In contrast, female free-tailed bats, T. brasiliensis, give birth to a single precocial young each year (Pagels and Jones, 1974; Sherman, 1937), and generally roost in man-made structures throughout the year in Florida (Bain, 1981). Roost mortality is unknown in the Florida Tadarida populations, but was estimated at 1.8% for Texas cave populations (Davis et al., 1962). We monitored mortality in an attic-dwelling colony of M. austroriparius and T. brasiliensis during the spring and summer of 1983. These data supplement information provided for M. austroriparius by Foster et al. (1978), and compare mortality in two species, M. austroriparius and T. brasiliensis, under identical roost conditions.