They emit tiny sounds or shrieks that last as long as .0002 to .1 seconds. These shrieks are at a frequency of 20,000 to 120,000 Hertzs, which is remarkable considering that the range of audible sounds for a human ear is between 20 to 20,000 Hertz. This would be the same as holding a smoke detector a few inches away from your ear. These high frequency sounds reflect back to the bat and the bat then interprets the information as to where and how close an object is. A bat usually emits about 10 to 50 calls in a second, when the bat gets close to its prey it can emit 200 or more calls per second.
Bats reproduce like other mammals in all basic aspects.
One unique thing about bat reproduction is that the sperm is stored in the reproductive tract during hibernation. This is because the ova haven't become fully matured and won't be until shortly after spring arrives. Mating occurs shortly after the finally awakening from hibernation usually in the fall, winter, or spring. Most bats only have one young, called a pup, at a time. At birth the pup is poorly developed except for the claws and the milk teeth designed to hold on to its mother's nipple.