Photos by Bill Rainey
Spotted bat has 3 white spots on a black body. Species is uncommon but widely distributed.
More than 900 bat species exist in the world--only missing from the Arctic and the Antarctic. Yosemite National Park houses 17 species (25 exist in California and 45 in North America). Bats are the only mammals capable of flight, as the scientific name of their order, Chiroptera, means hand-wing. Two divisions exist to the order, megachiroptera and microchiroptera. Megachiroptera species, found in the Old World, use vision to find their prey while microchiroptera species, found worldwide, use echolocation to find prey.
Bats, which are related to primates in an evolutionary sense, might be one of the tinier mammals, but their scientific biology is like the larger mammals: have only one young; young is born at 25% of the mother’s weight; lifespan of 34 years; and gestation 90-100 days.
Bats use a variety of roost sites in dark places, such as rock and bridge crevices, and buildings. Pallid bats began to roost outside The Ahwahnee just a year after the historic hotel was built.
North American bats undergo torpor or a daily “sleep” state. Bats maintain their body temperature only when active. During the day, while resting, bats let their body temperature drop to the temperature of their surroundings. If the surroundings are cold, bats enter a sluggish state of suspended animation, known as torpor. In order to avoid temperature fluctuations, bats look for locations to roost where they can let the weather regulate their temperatures—typically, in Yosemite, where it is a few degrees above freezing and where the temperature remains stable like in a rock crevice or a sequoia tree cavity. Some of the park’s species, studied as far back as the 1920s by Joseph Grinnell, migrate and some hibernate. At one time, textbooks indicated all bats hibernate, but not all do.
