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Name: Kejuan
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Question:
Why do bats always go out to hunt at night but not in the day?


Replies:
The answer to almost all "why" questions about nature is: Because it works. Most of the time we really can't say why a particular life style has evolved for any creature. We can often figure out how it works. Over the course of thousands of generations most species of bats have evolved special adaptations for hunting at night, especially the remarkable "sonar" system they use to navigate and locate prey. We know that it is a very successful adaptation because there are many species and individuals of bats that use it, and it gives bats an advantage in that few other creatures are competing for the abundant food offered by night flying insects. We really can't say what all the selection pressures were that originally started bats down that particular path.

J. Elliott


My guesses are:
1) because of the cool night temperatures. Bats are mammals and are warm blooded. Flying requires a lot of energy and generates a lot of excess body heat. So flying in the cooler temperatures at night helps the bats shed excess body heat in the cooler night air. This thought is re-enforced by their habit of roosting in dark cool caves during the day.

2) Another reason is because a lot of insects come out at night, like mosquitoes, fireflies, moths, and gnats.

3) Another reason is that the night air is cooler and has a higher density than the hot air during the day, making it easier to derive lift by flapping wings in cool, denser air.

Sincere regards,
Mike Stewart


Dr. Stewart has done some real thinking, and is right all down the line. Also, keep in mind that bats have developed echolocation which allows them to navigate at night, probably better than can be seen with their vision during the day. It is safer to hunt at night for predators and competition for food are all but eliminated; except of course with other bats.

Steve Sample


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