While bats are widely recognized as creatures of the night sky, their interaction with the ground is more varied than often assumed. Though primarily adapted for flight, bats occasionally find themselves on terrestrial surfaces. This can occur for various reasons, from natural behaviors to signs of distress. Understanding these circumstances provides insight into their unique biology and how to safely respond if one is encountered.
How Bats Are Built For Flight, Not Crawling
The anatomy of a bat is a testament to its aerial lifestyle, optimized for powered flight rather than efficient ground locomotion. A bat’s wing is a modified forelimb, featuring elongated finger bones that support a thin, elastic membrane called the patagium. This membrane extends from the body to these long digits, allowing for complex wing movements that generate lift and thrust. The bones themselves are lightweight and slender, reducing body mass to enhance flight efficiency.
Conversely, a bat’s hind limbs are not structured for walking or running like those of most terrestrial mammals. These legs are small and slender, primarily serving to allow bats to hang upside down while roosting. Their knees are rotated backward, an adaptation that facilitates hanging but makes upright ground movement awkward and inefficient. While bats possess a clawed thumb (pollex) on their wing and sometimes claws on their hind feet, these are mainly used for climbing or roosting, not sustained terrestrial travel. Moving on the ground requires significant energy for most bat species, as their bodies are simply not designed for it.
When and Why Bats Might Be on the Ground
Bats may be found on the ground for a variety of reasons, some normal and brief, others indicating a need for assistance. Occasionally, a bat might accidentally fall from its roost, especially if it’s a young or inexperienced bat learning to fly. Some species briefly land to drink water from a source. While rare for most species, a few bats, like certain insectivorous types, might briefly land to forage for ground-dwelling insects. Bats may also seek temporary shelter from predators or adverse weather conditions by landing on the ground.
However, some bat species exhibit specialized ground movement. The common vampire bat (Desmodus rotundus) is a notable exception, having evolved unique adaptations for terrestrial locomotion. These bats can walk, run, and even hop quadrupedally, using their strong hind limbs and modified wrist joints or thumbs to propel themselves. This ability is crucial for them to approach sleeping prey on the ground to feed. Another example is the lesser short-tailed bat from New Zealand, which can also walk and forage on the ground, using its forelimbs to move.
More concerningly, a bat on the ground can indicate distress. An inability to fly due to injury, illness, or severe dehydration and exhaustion can leave a bat grounded. Bats might also become entangled in netting or other obstacles, preventing them from taking flight. A bat found on the ground during daylight hours, acting disoriented, unable to fly, or exhibiting unusual aggression, could potentially be sick, possibly with rabies. While rabies in bats is not common, any bat showing these behaviors should be approached with caution.
What to Do if You See a Bat on the Ground
If you encounter a bat on the ground, it is important to exercise caution and avoid direct contact. Never attempt to touch a bat with bare hands, regardless of its apparent condition, as bats can bite in self-defense and may carry diseases like rabies. Bat bites can be tiny and go unnoticed, potentially transmitting the virus. It is best to observe the bat from a safe distance without disturbing it.
The most appropriate action is to immediately contact local animal control, a wildlife rehabilitator, or public health officials. These professionals are equipped to handle the situation safely, assess the bat’s health, and determine the best course of action. While waiting for professional help, keep children and pets away from the bat to prevent any potential interaction. If advised by an expert, a bat can be temporarily contained without direct contact by placing a box over it and sliding cardboard underneath, ensuring air holes. A grounded bat is more likely to be scared, exhausted, or sick than aggressive, but safety precautions are always paramount.