Evening bat
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The evening bat (Nycticeius humeralis) is a species of bat in the vesper bat family that is native to North America.[1] Hunting at night, they eat beetles, moths, and other flying insects.
Description
The evening bat is a small bat weighing Template:Cvt[2] found throughout much of the midwestern and eastern United States. Their forearms are Template:Cvt in length.[3] The tip of each dorsal hair is a light gray, and one to two-thirds of the basal is dark brown. Though there have been some cases of white pelage, the majority of the population is mostly brown in color.[3] They have wide, dog-like muzzles, pronounced facial glands, and disproportionately large bacula.[3][4] Evening bats can be mistaken for juvenile big brown bats, due to their physical resemblance but smaller size.
Morphology
Evening bats have relatively robust jaws, compared to other insectivorous bats.[5] They have an unkeeled calcar and a short, round tragus.[6] The curvature of the tragus helps distinguish it from bats of the genus Myotis, which otherwise look very similar.[6] Their skull has one upper incisor on each side with 4 molariform teeth.[7]
Biology
The evening bat is a relatively short-lived, especially compared to other bats in its geographic range.[8] It has a maximum age of 6 years, though few individuals live past 4 years.[9][8] Its short lifespan for a bat could be explained by its considerably higher reproductive output. Bats that only have one pup per year would need to live much longer to have the same fitness as a shorter-lived species with two or three pups per year.[8]
Reproduction
Evening bats mate in the fall and winter; the sperm is stored until the spring, when fertilization occurs.[10] Female bats form maternity colonies in May,[11] consisting of 15-300 individuals.[2] Of females that give birth, 90% have twins, but singletons and triplets are also possible.[10][11][12] Though it is more common for evening bats to nurse their own offspring,[2] a small proportion of offspring are nursed by unrelated females. The pups are capable of flight within a month of birth.[11] Pups are weaned within 42 days of birth.[2] Female pups exhibit natal philopatry, meaning that as adults, they return to the roost where they were born to give birth.[2]
Diet
These bats have varied diets. A majority of the bats' diet in Indiana and Illinois are beetles, including the spotted cucumber beetle, which is a serious agricultural pest.[13] In southern Illinois, the spotted cucumber beetle is almost 25% of the evening bats' diet.[14] Other beetles consumed include ground beetles and scarab beetles.[13] Moths are also a significant dietary component.[13] Bugs, winged ants, and flies are prey items of less significance.[14][15] Evening bats partition resources with other insectivorous bats in their range, such as the eastern red bat and Seminole bat.[15] Despite foraging in the same areas at the same time, these three bat species choose different prey items at different points throughout the summer.[15]
Distribution
At first, the evening bat was thought of as a southeastern bat species.[16] However, breeding evening bats have been found as far north as Michigan and as far west as the 100th meridian.[12] Evening bats roost in a variety of structures, including Spanish moss, under bark, in tree cavities, and in buildings.[17] For foraging habitat, evening bats in Georgia prefer pine forest, riparian zones, and open fields.[18] Evening bats have home ranges of approximately 300 hectare (1.15 mi2).[18] Because the evening bat is not found in the northernmost extent of its range in the winter, it is likely that at least some evening bats are migratory.[3]
Conservation
While the evening bat is considered endangered in the state of Indiana,[19] it has a cosmopolitan distribution throughout the southeast and midwest.[17] Because evening bats do not enter or hibernate in caves, the species is not at-risk from white-nose syndrome, which has killed over six million bats in the United States since 2006.[20] The evening bat's avoidance of this disease, along with die-offs of many other species, is possibly responsible for the evening bat recently expanding its range into Wisconsin in 2015 and Minnesota in 2016.[20][21]
| State | Conservation Status |
|---|---|
| Alabama | Lowest Conservation Concern |
| Arkansas | Not listed |
| Florida | Not listed |
| Georgia | Not listed |
| Illinois | Not listed |
| Indiana | State Endangered |
| Iowa | Not listed |
| Kentucky | Threatened |
| Kansas | Not listed |
| Louisiana | Not listed |
| Maryland | Not listed |
| Michigan | Threatened |
| Minnesota | Not listed |
| Mississippi | Not listed |
| Missouri | Not listed |
| Nebraska | Not listed |
| North Carolina | Not listed |
| Ohio | Species of Special Interest |
| Oklahoma | Not listed |
| Pennsylvania | Not listed |
| South Carolina | Not listed |
| Tennessee | Not listed |
| Texas | Not listed |
| Virginia | Not listed |
| West Virginia | Not listed |
| Wisconsin | Not listed |
References
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- ↑ Template:MSW3 Chiroptera
- ↑ a b c d e Script error: No such module "Citation/CS1".
- ↑ a b c d Watkins, L. C. (1972). Nycticeius humeralis. Mammalian species, (23), 1-4.
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- ↑ a b Barbour, R., W. Davis. 1974. Mammals of Kentucky. Kentucky: The University Press of Kentucky.
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- ↑ a b c Austad, S. N. (2010). Cats,"rats," and bats: the comparative biology of aging in the 21st century. Integrative and comparative biology, icq131.
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- ↑ a b Whitaker, J. O., Jr., J. B. Cope, D. W. Sparks, V. Brack, Jr., and S. Johnson. Bats of Indiana. Publication no. 1, ISU Center for North American Bat Research and Conservation. Indiana State University. 59 pp.
- ↑ a b c Watkins, L. C., & Shump Jr, K. A. (1981). Behavior of the evening bat Nycticeius humeralis at a nursery roost. American Midland Naturalist, 258-268.
- ↑ a b Kurta, A., Foster, R., Hough, E., & Winhold, L. (2005). The evening bat (Nycticeius humeralis) on the northern edge of its range—a maternity colony in Michigan. The American midland naturalist, 154(1), 264-267.
- ↑ a b c Whitaker Jr, J. O., & Clem, P. (1992). Food of the evening bat Nycticeius humeralis from Indiana. American Midland Naturalist, 211-214.
- ↑ a b Feldhamer, G. A., Whitaker Jr, J. O., Krejca, J. K., & Taylor, S. J. (1995). Food of the evening bat (Nycticeius humeralis) and red bat (Lasiurus borealis) from southern Illinois. Transactions of the Illinois Academy of Science, 88, 139-143.
- ↑ a b c Carter, T. C., Menzel, M. A., Chapman, B. R., & Miller, K. V. (2004). Partitioning of food resources by syntopic eastern red (Lasiurus borealis), Seminole (L. seminolus) and evening (Nycticeius humeralis) bats. The American midland naturalist, 151(1), 186-191.
- ↑ Script error: No such module "Citation/CS1".
- ↑ a b Menzel, M. A., Carter, T. C., Ford, W. M., & Chapman, B. R. (2001). Tree-roost characteristics of subadult and female adult evening bats (Nycticeius humeralis) in the Upper Coastal Plain of South Carolina. The American Midland Naturalist, 145(1), 112-119.
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