24: Big Brown Bat

I write to you from Arapahoe, Ute, and Cheyenne land. I am interested in learning about the different animals that live in the place where I was born. I want to mention that biological classification as taught by western science has its roots in racism, sexism, and transphobia – here’s a good explainer about why.

Have you been outside at night and seen bats flying around, often near street lights or if you’re at Red Rocks on a night without a show, hanging out by the light fixtures backstage? Chances are, the bats you’re seeing are Big Brown Bats (Eptesicus fuscus), who actually are pretty big – they can have a wingspan of over a foot! They are insectivorous and love to eat beetles, including agricultural pests like the cucumber beetle.

I LOVE bats. I used to handle them for kids at a museum and they are such sweet, gentle creatures. They are the only mammals capable of sustained flight (a flying fox is actually a bat, not a canine) and they are the second largest group of mammals alive today, after rodents. In fact, bats comprise 20% of all classified mammal species worldwide, and there are over 1400 known species! Bats are traditionally divided into “megabats” and “microbats”, two classes I would have greatly preferred in college to “macroeconomics” and “microeconomics”.

Of course bats have a bad rap right now, and, aside from rodents, carry more human-infecting viruses than any other animal. The reason why is not totally understood but scientists believe it is because their colonies – where they all hang out in damp places and breath together while resting – are great incubators for respiratory diseases. As for why they don’t get sick, well, very recent research from the Wuhan Institute of Virology (see the link above) shows that it is because their immune systems are much better than ours at responding to them. But I think we can all agree that it isn’t the bats’ fault that we’re in a global pandemic – it is the fault of humans encroaching on bats’ territory.

So, back to the Big Brown Bat. They are a vesper bat, from the Latin “vesper” meaning evening. They are also a microbat (as all vesper bats are), meaning that they use echolocation to navigate. They like to take advantage of human-made objects to roost, and can be found in mines and storm cellars (or behind the stage at Red Rocks). As a result, they are commonly seen in towns and cities. They hibernate during the winter after storing around 30% of their body weight. Females roost in maternity colonies in the spring, with around 300 individuals – this is an effective way to keep their young warm, surrounded by many other bat bodies. Mothers can recognize their babies even amongst hundreds of others – if a baby falls to the floor, its mother will swoop down to carry it back up to the roost.

Here’s a cool thing about the BBB: they have incredible homing ability. They can return to their roost site from over 400 miles away, and can return 40 miles in a single night.

This entry is fortuitous because it is BAT WEEK! If you want to, you can even build a bat box to help the Big Brown Bat navigate the Anthropocene world.