Featured Image Caption: Bats are some of the most fascinating and often underappreciated animals. The only mammals capable of flight, bats rely on echolocation to find prey, avoid obstacles, and now communicate with other bats (Source: Karin Schneeberger via Wikimedia Commons).
Reference: Kohles, J. E., Carter, G. G., Page, R. A., & Dechmann, D. K. N. (2020). Socially foraging bats discriminate between group members based on search-phase echolocation calls. Behavioral Ecology, 31(5), 1103-1112. https://doi.org/10.1093/beheco/araa056
Can you help me look?
How often do you lose your keys or phone? If you’re like me, it’s a daily struggle. I usually enlist help to find the lost items faster. When more people help me look for something, I can cover more ground and save time. While searching, I communicate with others about where they are and where they have been. Has anyone checked the bedroom? The living room? The kitchen? I don’t want to waste time searching where someone has already looked.
Bats do the same thing! However, bats search for food. There are over 1000 species of bats, and not all species are social. Those that are social hunt for food together. Group hunting tends to happen when prey is hard to find but abundant once found. That way, there is enough food to go around to all group members who helped search. Just like humans, a recent study by Jenna Kohles and her colleagues found that bats communicate while searching so they know who is there and where they are. Bats are nocturnal, so using visual cues to determine this information can be challenging. Instead, bats use components of searching calls to identify individual group members!
Bats are often portrayed negatively, especially during discussions about COVID-19. However, bats are extremely important for our health and the well-being of our environment. One bat eats thousands of pests each night, which can include hundreds of pesky mosquitos. Additionally, bat populations are declining due to the deadly white-nose syndrome, climate change, and habitat loss. We need bats, and bats need our help. We can help bats by learning more about them and spreading the news of how fascinating and important they are!
The Bat Chat
Echolocation is when animals use echoes (sound waves that bounce off of a surface) to determine where objects are located around them. Bats use echolocation to find and capture prey. The sounds bats produce for echolocation are above human hearing, which is a good thing since the calls can be as loud as a plane engine! Bats use two types of echolocation calls: search-phase calls and feeding buzzes. Bats produce the search-phase call to scan the environment for obstacles and their next meal. Once prey is located, bats use feeding buzzes to capture the item. Feeding buzzes provide social information by notifying other bats that prey is nearby. Jenna Kohles and her collaborators wanted to know if social information is also contained in search-phase calls of the velvety free-tailed bat (Molossus molossus).
Like humans, bats each have a unique voice. You would probably know which friend is talking to you in a dark room by identifying their voice. The researchers wanted to see if bats can also discriminate and identify individual bats in their group. They recorded search-phase calls from individual bats from different social groups. They analyzed each call to see if they had unique features that the bats could use to identify individuals. Then, the researchers played back the recorded calls of different group members. In doing so, they could determine if bats recognized members by behaving differently between individuals and consistently with the same individuals.
The search-phase calls from different individuals had unique features that bats could use to discriminate between group members. The results further showed that bats indeed use these unique features to identify individuals. These findings suggest that bats use calls that have evolved for locating food to broadcast social information. If bats had evolved a different call to communicate with group members, they would have to alternate between searching and communicating. Since search-phase calls allow bats to identify groupmates, bats can search and communicate at the same time! Aren’t bats remarkable?
Even though we cannot hear them, bats produce calls all night long while we are fast asleep. These calls help them identify objects, food, and, as we have learned, group members. Bats are important for pollination and for keeping insect populations in check, but their populations are declining due to human disturbance and the deadly white-nose fungus. The US National Parks Service has put together an informative website where you can learn more about bats and how we can protect them!