Nycticeius humeralis
| Evening bat | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Chiroptera |
| Family: | Vespertilionidae |
| Genus: | Nycticeius |
| Species: | N. humeralis |
| Binomial name | |
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Nycticeius humeralis (Rafinesque, 1818) |
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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.
The evening bat is a small bat (7–15 grams) found throughout much of the midwestern and eastern United States. Their forearms are 34–38 mm (1.33 in) in length. 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. They have wide, dog-like muzzles, pronounced facial glands, and disproportionately large bacula. Evening bats can be mistaken for juvenile big brown bats, due to their physical resemblance but smaller size.
Evening bats have relatively robust jaws, compared to other insectivorous bats. They have an unkeeled calcar and a short, round tragus. The curvature of the tragus helps distinguish it from bats of the genus Myotis, which otherwise look very similar. Their skull has one upper incisor on each side with 4 molariform teeth.
The evening bat is a relatively short-lived, especially compared to other bats in its geographic range. It has a maximum age of 6 years, though few individuals live past 4 years. 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.
Evening bats mate in the fall and winter; the sperm is stored until the spring, when fertilization occurs. Female bats form maternity colonies in May, consisting of 15-300 individuals. Of females that give birth, 90% have twins, but singletons and triplets are also possible. Though it is more common for evening bats to nurse their own offspring, a small proportion of offspring are nursed by unrelated females. The pups are capable of flight within a month of birth. Pups are weaned within 42 days of birth. Female pups exhibit natal philopatry, meaning that as adults, they return to the roost where they were born to give birth.
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Wikipedia