How Many Offspring Does a Gray Bat Have and How Often Do They Have Them?

The gray bat, or Myotis grisescens, is an endangered species that lives in areas throughout 12 states, including Missouri, Tennessee, Alabama, Illinois, Indiana and Florida. They weigh only 0.4 to 0.16 g and have a wingspan of up to 12 inches. They feed primarily on insects and almost 95 percent of them spend most of their time roosting within only eight different cave systems, which are located in five states: Tennessee, Missouri, Kentucky, Alabama and Arkansas. Locations in other states are mostly migratory.

  1. Mating Process

    • Adult gray bats mate during September and October, just before hibernating for the winter months. They can retain sperm through their hibernation and become pregnant in the spring when they reawaken.

    Maternity Colonies

    • Pregnant female gray bats live in large colonies of other pregnant gray bats, called "maternity colonies." These colonies take up residence in caves where warmth can accumulate by body heat or where air flows are weak enough so cool drafts do not keep the temperature too low. Baby gray bats grow faster and healthier if they are kept warm. Nonpregnant females, juveniles and male bats roost in separate colonies.

    Number of Offspring

    • Gray bats only give birth to one pup per year, usually during late May or early June. Their young are able to grow and mature within a month, so adult female bats can breed again and produce another baby the next year.

    Raising Young

    • Baby and juvenile gray bats stay with their mothers until they are old enough to fly on their own. For the first week, they cling to their mother's back or stomach and nurse from her to gain sustenance. At around 20 to 25 days after birth, the juveniles are able to fly and leave their mother's protection.