Bats are the only flying mammals that are active mostly at night and occur on all continents except Antarctica. Bats are ecologically diverse, with a range of species that specialize in feeding on fruit, nectar, blood, fish, small mammals, and insects. However, of the more than 1,100 known species of bats on Earth, the majority specialize in feeding on insects. In the United States for example, of the 45 different species of bats, 42 are insectivorous. These small creatures of the night are diverse in shape and size, with most relying on echolocation to detect insect prey and find their way through darkness. Many of these bats form colonies that feed on seasonally available insects from spring to autumn.
Most insectivorous bats use seasonal feeding strategy to help build fat reserves during the summer and autumn, prior to their hibernation during winter - a time, generally, when insects are not available throughout most of the United States. Some of these bat species do not hibernate but instead migrate seasonally. It is believed that the timing of migration and routes that they take, such as those for the hoary bat (Lasiurus cinereus), might coincide with availability of their preferred insect prey.
Recently, many insectivorous bat species have suffered drastic declines in numbers due to new environmental stressors, both natural and human caused. One of these stressors is the emerging wildlife disease known as white-nose syndrome (WNS). This disease is caused by the fungus Pseudogymnoascus destructans and has been devastating colonies of hibernating bats in the eastern United States for several years. At present, there is no known cure for WNS, which continues to spread north-, south-, and westward. It is likely that the effects of declining insectivorous bat populations will influence insect populations, including possible increases, in some geographic areas of insects that are economic pests.
Like WNS, the development of alternative energy in the form of industrial wind energy facilities is also having a harmful effect on bats through collisions with moving turbine blades. These fatal encounters often coincide with the autumn migration of bats. Why certain bats are susceptible to turbines remains unknown, yet feeding on insects may play a role in bat susceptibility. For example, the hoary bat is killed more often than any other species of bat at wind turbines in North America, and it is believed that certain prey types (e.g., noctuid moths) consumed by these bats may be locally and seasonally abundant around wind energy facilities.
Despite the high species and ecological diversity of insectivorous bats in the United States, little information exists on their diet. At FORT, biologists are investigating dietary habits of insectivorous bats, which will help provide insight into questions related to climate change, energy development, wildlife diseases, and conservation.
Below are publications associated with this project.
Seasonal shifts in the diet of the big brown bat (Eptesicus fuscus), Fort Collins, Colorado
Insect prey eaten by Hoary Bats (Lasiurus cinereus) prior to fatal collisions with wind turbines
Status and Natural History of Emballonura Semicaudata Rotensis on Aguiguan, Mariana Islands
Bats of Mesa Verde National Park, Colorado: Composition, reproduction, and roosting habits
Food habits of the hoary bat (LASIURUS CINEREUS) during spring migration through new mexico
Late-seasonal activity and diet of the evening bat (Nycticeius humeralis) in Nebraska
Food habits of Nyctinomops macrotis at a maternity roost in New Mexico, as indicated by analysis of guano
Below are partners associated with this project.
- Overview
Bats are the only flying mammals that are active mostly at night and occur on all continents except Antarctica. Bats are ecologically diverse, with a range of species that specialize in feeding on fruit, nectar, blood, fish, small mammals, and insects. However, of the more than 1,100 known species of bats on Earth, the majority specialize in feeding on insects. In the United States for example, of the 45 different species of bats, 42 are insectivorous. These small creatures of the night are diverse in shape and size, with most relying on echolocation to detect insect prey and find their way through darkness. Many of these bats form colonies that feed on seasonally available insects from spring to autumn.
Examples of Insect fragments belonging to ground beetles, water boatmen, click beetles, weevils, scarabs, and adult antlions identified from various dissected guano pellets of different bat studies. Photo by: Ernest Valdez, USGS. Public domain. Allen's big-eared bat (Idionycteris phyllotis), an insectivore known from the southwestern United States. Photo by: Ernest Valdez, USGS. Public domain. Most insectivorous bats use seasonal feeding strategy to help build fat reserves during the summer and autumn, prior to their hibernation during winter - a time, generally, when insects are not available throughout most of the United States. Some of these bat species do not hibernate but instead migrate seasonally. It is believed that the timing of migration and routes that they take, such as those for the hoary bat (Lasiurus cinereus), might coincide with availability of their preferred insect prey.
Recently, many insectivorous bat species have suffered drastic declines in numbers due to new environmental stressors, both natural and human caused. One of these stressors is the emerging wildlife disease known as white-nose syndrome (WNS). This disease is caused by the fungus Pseudogymnoascus destructans and has been devastating colonies of hibernating bats in the eastern United States for several years. At present, there is no known cure for WNS, which continues to spread north-, south-, and westward. It is likely that the effects of declining insectivorous bat populations will influence insect populations, including possible increases, in some geographic areas of insects that are economic pests.
Brazilian free-tailed bat (Tadarida brasiliensis), a migratory insectivore known to consume insect pests of agriculture. Photo by: Ernest Valdez, USGS. Public domain. Like WNS, the development of alternative energy in the form of industrial wind energy facilities is also having a harmful effect on bats through collisions with moving turbine blades. These fatal encounters often coincide with the autumn migration of bats. Why certain bats are susceptible to turbines remains unknown, yet feeding on insects may play a role in bat susceptibility. For example, the hoary bat is killed more often than any other species of bat at wind turbines in North America, and it is believed that certain prey types (e.g., noctuid moths) consumed by these bats may be locally and seasonally abundant around wind energy facilities.
Despite the high species and ecological diversity of insectivorous bats in the United States, little information exists on their diet. At FORT, biologists are investigating dietary habits of insectivorous bats, which will help provide insight into questions related to climate change, energy development, wildlife diseases, and conservation.
In the distance is Aguiguan (aka Goat Island), Commonwealth of the Northern Mariana Islands; only known location for the endangered Pacific sheath-tailed bat (Emballonura semicaudata rotensis) seen above in carousel. Photo by: Ernest Valdez, USGS. Public domain. - Publications
Below are publications associated with this project.
Seasonal shifts in the diet of the big brown bat (Eptesicus fuscus), Fort Collins, Colorado
Recent analyses suggest that the big brown bat (Eptesicus fuscus) may be less of a beetle specialist (Coleoptera) in the western United States than previously thought, and that its diet might also vary with temperature. We tested the hypothesis that big brown bats might opportunistically prey on moths by analyzing insect fragments in guano pellets from 30 individual bats (27 females and 3 males) cAuthorsErnest W. Valdez, Thomas J. O'SheaInsect prey eaten by Hoary Bats (Lasiurus cinereus) prior to fatal collisions with wind turbines
Wind turbines are being deployed all across the world to meet the growing demand for energy, and in many areas, these turbines are causing the deaths of insectivorous migratory bats. One of the hypothesized causes of bat susceptibility is that bats are attracted to insects on or near the turbines. We examined insect remains in the stomachs and intestines of hoary bats (Lasiurus cinereus) found deaAuthorsErnest W. Valdez, Paul M. CryanStatus and Natural History of Emballonura Semicaudata Rotensis on Aguiguan, Mariana Islands
Pacific sheath-tailed bats (Emballonura semicaudata rotensis) in the Mariana Islands declined greatly in abundance and distribution during the 20th century. The small island of Aguiguan now supports the only persisting population. We studied abundance and natural history of this population from 1995–2008. There was a likely population increase during the study, with 359–466 (minimum and maximum) bAuthorsGary J. Wiles, Thomas J. O'Shea, David J. Worthington, Jacob A. Esselstyn, Ernest W. ValdezBats of Mesa Verde National Park, Colorado: Composition, reproduction, and roosting habits
We determined the bat fauna at Mesa Verde National Park (Mesa Verde) in 2006 and 2007, characterized bat elevational distribution and reproduction, and investigated roosting habits of selected species. We captured 1996 bats of 15 species in mist nets set over water during 120 nights of sampling and recorded echolocation calls of an additional species. The bat fauna at Mesa Verde included every speAuthorsThomas J. O'Shea, Paul M. Cryan, E. Apple Snider, Ernest W. Valdez, Laura E. Ellison, Daniel J. NeubaumFood habits of the hoary bat (LASIURUS CINEREUS) during spring migration through new mexico
Hoary bats (Lasiums cinernis) exhibit continental patterns of migration that are unique to bats, but details about their behaviors during migration are lacking. We captured 177 hoary bats in spring and early summer 2002 as individuals migrated through the Sandia Mountains of north-central New Mexico. Our results support earlier observations of asynchronous timing of migration between sexes of L. cAuthorsE.W. Valdez, P.M. CryanLate-seasonal activity and diet of the evening bat (Nycticeius humeralis) in Nebraska
In North America, Nebraska represents part of the northwestern edge of the distribution for the evening bat (Nycticeius humeralis). To date, little information on this bat's natural history has been published from the state or from other parts of the Great Plains. Here we report on aspects of its natural history in Nebraska from 2 localities. In late summer and early autumn of 2006, we documentedAuthorsKeith Geluso, J.P. Damm, E.W. ValdezFood habits of Nyctinomops macrotis at a maternity roost in New Mexico, as indicated by analysis of guano
We examined 56 fecal pellets from under a maternity colony of big free-tailed bats (Nyctinomops macrotis) in the Jemez Mountains of northern New Mexico. The most important food items, listed in order of decreasing percent volume, were Cicadellidae, leafhoppers (26.7% volume, 58.9% frequency); Ichneumonidae, Ichneumon wasps (19.3% volume, 35.7% frequency); and Lepidoptera, moths (17.2% volume, 82.1AuthorsD. W. Sparks, E.W. Valdez - Partners
Below are partners associated with this project.