We’re still learning about bat intelligence

And what we’re learning is fascinating

Nectar eating bats drink sugar water from hummingbird feeders. I learned more about this from, Mallory, a biologist who was studying lesser long-nosed bats (Leptonycteris yerbabuena). She came to our house one night to net bats to get DNA samples and place tiny transmitters on them, hoping to learn about the genetics of the species and the bats’ movements.

Mallory explained why my feeders, full in the evening after the hummingbirds have gone wherever they go to sleep, would be empty in the morning. I didn’t mind feeding two species, or buying bulk sugar. I love watching the hummingbirds, warrior birds that they are, as much as the bats.

Some bats echolocate to find flowers Photo by Zdeněk Macháček on Unsplash

But let’s start with some bat basics. Bats are the only mammals that can fly. Interesting factoid: the bones in their wings are more similar to the bones in our hands and arms, than those in bird wings. Bats use echolocation, ultrasonic waves that bounce off objects and return to the bats’ ears. They use different sounds for hunting, feeding and social interactions. They can also see using sound. When their mouths are opened wide, they are able to focus on the sound in small spaces. They make their mouths smaller when trying to ‘see’ in bigger spaces.

I also learned from Mallory that, for the long-nosed bats in my area, my hummingbird feeders were a helpful food source, especially during times when blooming agaves, whose nectar they rely on, are scarce. And this can happen often, as agaves only bloom every 6-10 years.

But Mallory also warned me to take down my feeders at night in late summer and early autumn when the bats should be starting their migration. They might be tempted to stay around a reliable food source, but if they stayed too long, they would be unlikely to survive the winter. Reducing their food supply forces them to migrate to their wintering sites further south. Meanwhile some of the hummingbirds would still be around, and since some of those species will make their migration later, it’s helpful for them to have a reliable food source to help them bulk up for their journey. My feeders don’t come down until early winter.

But no matter how the form may vary, the fact that an organism has conscious experience at all means, basically, that there is something it is like to be that organism. Thomas Nagel

Unlike many people who fear bats, I’ve been fascinated by them since learning about their use of sonar. For example, bats that consume insects use sonar to find their prey. But sometimes their prey, moths for example, on detecting the bats’ echolocation frequencies, will take evasive action. Those maneuvers vary depending on how close or far away the bat sounds are from the moth. Some of these moths are now comfortable flying in straight paths when no bats are heard, only using more erratic flight patterns, which use more energy, when bats are nearby. But bats also change their behavior to compensate. Some big-eared bats listen rather than echolocate to find moths. Not so different to the giraffe v acacia evolutionary battle.

A recent study suggests that lesser long-nosed bats use echolocation to locate and classify cactus flowers, then they can fly straight in and place their long noses in the flower opening. When cacti in the study were replaced by an artificial substitute, the bats didn’t attempt to insert their noses. And the way they approached these targets was different. Flight direction often changed, and they stayed farther away from the substitutes.

Echolocation also provides detailed information when bats are communicating. When in their caves or other large group situations, Egyptian fruit bats (Rousettus aegyptiacus) can identify who is echolocating, who they are ‘talking’ to, and details of the communication’s content, for example whether they are fighting over food sources, rejecting mating advances by a male, or disputing over perching and sleeping places. Based on their study the researchers were often able to predict outcomes of interactions, such as which bat would leave the perch or sleeping area.

Several species of bat regularly rest in our front entryway when not feeding. I don’t mind them being there. We rarely use the front door, and they don’t seem bothered on those few occasions when one of us ventures out that way. I haven’t stopped trying to imagine what happens in the mind of a bat. I’m just glad to be able to observe them on my land.