Evening bat
| 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, Vespertilionidae, that is native to North America. It is a small bat (7–15 grams) found throughout much of the midwestern and eastern United States. 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. The evening bat was originally thought to be a juvenile big brown bat, due to its physical resemblance but smaller size. After careful evaluation, it was discovered that the evening bat was its own species.
Evening bats are considered microchiropterans which means they have some sort of facial ornamentation. These bats with facial ornamentation tend to be more efficient in echolocation, whereas their counterparts, megachiropterans, abandon or use less of this hunting/communication method and rely more on visual and olfactory senses. Because they're microchiropterans, the evening bat is very efficient at echolocating. In bats, echolocation originates from the larynx.
These bats have a massive skull in proportion to their bodies and have a large, strong jaw. With a stronger jaw, it is more capable of crunching down on insects such as beetles or moths. Their teeth have relatively precise occlusion with large incisors on both the maxilla as well as the mandible. Their eyes are on the sides of their head, giving them monocular vision. In many cases, this could be considered evolutionary un-advantageous; However, because the evening bat is nocturnal and echolocates, it does not rely much on sight. Their tails, ears, and wings are quite thick and leathery for being a smaller bat. In addition, microchiropterans do not have a claw on their second finger in comparison to megachiropterans.
Though it is more common for N. Humeralis to nurse their own offspring, in a relatively recent study done by G.S. Wilkinson in 1992 it has been observed in numerous colonies that there is a small portion of offspring that are nursed by un-related lactating females. Lactation is one of the most expensive parts of reproduction in mammals, thus, it is usually not beneficial to nurse more than needed. As the study goes on to describe, the average body mass of the lactating female bats went down significantly during their highest rates of lactation and demand whereas when the pups began to grow older and learn to fly, the female body mass began to increase; However, interestingly, this is when communal nursing began to become more apparent.
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