Effects of roost specialization on extinction risk in bats

Abstract
Understanding causes and consequences of ecological specialization is of major concern in conservation. Specialist species are particularly vulnerable to human activities. If their food or habitats are depleted or lost, they may not be able to exploit alternative resources, and population losses may result. We examined International Union for Conservation of Nature (IUCN) Red List bat data and the number of roosts used per species (accounting for phylogenetic independence) to determine whether roost specialization is correlated with extinction risk. We found a significant correlation between the IUCN Red List category and the number of roost types used. Species that use fewer roost types had a higher risk of extinction. We found that caves and similar structures were the most widely used roost types, particularly by species under some level of risk of extinction. Many critically endangered, endangered, or vulnerable species used natural roosts exclusively, whereas less threatened species used natural and human-made roosts. Our results suggest that roost loss, particularly in species that rely on a single roost type, may be linked to extinction risk. Our focus on a single life history trait prevented us from determining how important this variable is for extinction risk relative to other variables, but we have taken a first step toward prioritizing conservation actions. Our results also suggest that roost specialization may exacerbate population declines due to other risk factors, such as hunting pressure or habitat loss, and thus that management actions to preserve species under risk of extinction should prioritize protection of roosting sites.

In the last issue of Conservation Biology M. Sagot and G. Chaverri present a new paper called “Effect of roost specialization on extinction risk in bats”.

The study of bats’ roosts is very important for different reasons. First, bats spend at least half of their life in the roost. They are also protected from predators and inclement weather. Finally, it is well known that roosts are used for rearing young. All these factors make roosts vital for the survival and reproduction of bat species. Roosts also provide, a very important location for social interactions, like copulation, grooming and feeding.

Bats use a variety of roosts like caves, cliffs, tree cavities, banks and ledges, tree bark, human-made buildings and structures, leaf litter, tree boles, bamboo culm, modified leafs as tents, stems, foliage, termite nests, bird nests and furled leaves. Some species use several roost types and others use only one kind of structure and are roost specialists.

The article by Sagot and Chaverri tested the hypothesis that “species that use fewer roost types are at greater risk extinction, as defined by the International Union for Conservation of Nature (IUCN) Red List of Threatened Species”. IUCN uses different categories for its list: CR, critically endangered; EN, endangered; VU, vulnerable; NT, near threatened; and LC, least concern.

round ~24% of all bat species are under some kind of threat as a result of anthropogenic activities. The article focuses on 385 bat species (18 families and 128 genera) distributed worldwide. The species displayed a diverse range of diets (carnivorous, piscivorous, sanguinivorous, nectarivorous, insectivorous and frugivorous). Read More... mgambarios.com / effect-of-roost-specialization-on-extinction-risk-in-bats