Tuesday, March 10, 2015

Coqui Frog Gets Smaller, Song Gets Briefer & Higher

I am always curious about how our little creatures deep in the forests are experiencing changes due to our creation of more carbon dioxide in our global air. Let's take a look at the little coqui frog in the forests of Puerto Rico. The coqui has existed for more than 11,000 years and is a beloved protagonist in Puerto Rico's folklore, songs, and children's books.

UCLA Professor of Biology Peter Narins has been studying the coqui for 41 years. In 1983, he began a longitudinal study of the coqui, studying male frogs at 28 different altitudes, from near to sea level to up in the highest hills. Checking back in two decades later in 2006, he found that frogs had grown smaller, which is consistent with moving upward in elevation due to a rise in ambient temperature. Basically, the frogs found their current elevation too hot, so they moved upward in elevation, thus causing their offspring to be smaller as they migrated upward. During this same time period, the temperature had raised .5 degrees.

Not only had the frogs migrated to a higher elevation, but their songs had changed. Usually in Puerto Rico, the frogs at a lower elevation are shorter with a higher pitch in comparison with the lower, long songs of their brethren in the hills. Narins and his research partner Sebastiaan Meenderink found that, within a certain elevation, over the 2 decades, the frogs' song pitch had risen and also had grown shorter in duration.

The song is used for two purposes: the "co" part of the song is for territorial defense against other males, while the "-qui" part of the song is intended to impress female coqui frogs. Since the purpose of the latter song is to attract females to mate with, scientists predict that the briefer, higher-pitched song will decrease the coqui's reproductive success. In other words: briefer & higher song, fewer coqui females attracted, fewer baby coquis grown. This spells potential trouble, since the coqui exists within an entire interdependent web: the coquis are the prey of other animals such as "owls, snakes, land crabs," according to Stuart Wolpert.

Read the original research here

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