Jamaican bats can smell food and drive themselves bananas

Abstract

Imagine that you are approaching home. Suddenly, you come across the smell of your favourite casserole, and it is so strong that you could almost close your eyes and let the smell guide you. While humans can use their sense of smell to decide whether or not that new recipe they just tried is edible, other animals can also take advantage of sniffing around to make their way to delicious food. Now, we all know that bats excel at using echolocation, their unique navigation system to make their way around their environment. However, it turns out that Jamaican fruit-eating bats (Artibeus jamaicensis) can very much exploit their olfactory system to complement their echolocation system and find a delicious treat, such as a banana.To expand on what we already know about Jamaican bats and their smelling capabilities, Alyson Brokaw and Michael Smotherman from Texas A&M University, USA, with Evynn Davis from Johns Hopkins University, USA, and Rachel Page from the Smithsonian Tropical Research Institute, Panama, collaborated in a fun new study where they set a group of Jamaican bats the exciting challenge of identifying a succulent banana using their sense of smell alone. Placing five stands (four holding banana-shaped sponges and another holding a real banana) in an almost-dark medium-sized chamber, Brokaw and her collaborators allowed the inimitable flying mammals to roam around the room in search of the true banana. However, bats are very smart and could just use their echolocation system to identify the real deal. So, to account for this, Brokaw and her collaborators performed a second experiment where they replaced the real banana with a fifth banana-shaped sponge soaked in a delicious banana-scented syrup and waited to see how the bats reacted.Over the course of several days and multiple trials, Brokaw and colleagues measured the number of times the bat landed on the right target in both experiments, in addition to calculating the animals’ instantaneous velocity and their vertical distance from the target before they decided to land on the true or fake banana scented with syrup. It turned out that the Jamaican bats were correct 87% of the time and selected the scented targets, whether they were the real deal or the banana decoy. Also, the bats tended to slow down and get as close as 6 cm above the targets, swooping low at least 2 or 3 times to take a good sniff before they decided to land on their prize.So, bats can use their olfactory system to tease out the good from the bad targets by inspecting their options with their noses. Understanding how bats navigate their environment is important because it allows us to predict how changes in the landscape could have a direct impact on these animals. Bats are very clever animals: not only can they use spatial memory and echolocation to get a good idea of the landscape but they can also combine their olfactory and echolocation systems to decide which is the best banana hanging from the tree. Who knows, maybe Jamaican fruit-eating bats are as good at finding ripe bananas as pigs are at locating luscious truffles.