Cool bats

Posted on July 4, 2013 by Andrew Gray

Sac-winged bat (Rhynchonycteris naso) (c) A Gray

A couple of the student projects I’ve been supervising on this year’s field course have focused on investigating thermoregulation and roosting behavior in neotropical bats. Apart from recording the sounds made by Sac-winged bats (pictured) when they leave their daytime resting place, the external body temperatures of the sleeping bats were also measured using some of the infra-red equipment we have with us.

Bat body temperatures have been compared and correlated to the changes in daytime ambient temperatures by the 2 students, Irenke and Emma, and they’ve found that the bats appear to be much cooler than the ambient temperature when they return to roost in the early morning. This may suggest that the bats are able to cool down with the breeze on their wings during flight to compensate for heat generated by activity.

Sonagram of sound emitted by the Sac-winged bat (Rhynchonycteris naso). Courtesy of Alex Villegas

With over 100 species of bats occurring in Costa Rica, they fill a wide variety of niches. Many nectar and fruit eating bats help pollinate and disperse the seeds of a huge variety of tropical plants, while others prefer a more bloodthirsty diet – 3 species of vampire bat also occur here!

Tent-making Bat (Uroderma bilobatum) at rest (c) Andrew Gray

Today I arrived to the Caribbean coast, and as it happens found some little tent bats (Uroderma bilobatum) sleeping just outside where I’m staying (pictured). These belong to the family Phyllostomidae, and bats belonging to this family are also commonly known as leaf-nosed bats – because they are characterized by a special leaf-shaped nose structure which extends up from their upper lip. These bats send their echolocation calls out of their nostrils, so the nose may help direct the sounds that they emit, or help them locate food, such as ripe fruit and pollen, through smell. Hopefully they won’t be put out by my smelly rainforest attire, which must certainly remain outside until it’s washed! 🙂

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