Scientists use iPods, car batteries to build a frog surveillance net

Put this on your playlist: scientists at the University of Puerto Rico have developed a system to monitor wildlife in tropical rainforests, using captured audio in real time to remotely record the sounds made by animals. Using hardware that includes iPods, solar panels, and car batteries, the scientists created a network of radio-connected listening posts around the world that allows them to collect data 24 hours a day over long periods of time. The sound will help them track the effects of environmental changes-such as deforestation and climate change-on endangered species.

The system, called Arbimon (Automated Remote Biodiversity Monitoring Network), was created by a team led by Dr. Mitchel Aide and Dr. Carlos Corrada-Bravo of the University of Puerto Rico. As described in a paper published by the team in PeerJ today, Arbimon's monitoring stations use an iPod recording application to capture up to 144 one-minute audio recordings per day of animal calls. Most of the components of the monitoring stations-the iPod, the battery, a voltage converter, a preamplifier for the microphone, and a router-are in a sealed watertight case. A 50-watt solar panel powers the system and charges the battery during the day.

The collected audio is then transmitted over a 900MHz radio signal back to a collection base station-which can be up to 24 miles away-and is uploaded over the Internet to the team's server in Puerto Rico. Audio processing software on the server then attempts to automatically identify the species caught on the audio recordings; scientists can "teach" the system to improve its identifications or learn new species through a Web-based audio analysis application. The server can process over 100,000 recordings an hour, delivering data on the presence or absence of a species across the monitored sites.

The initial testing of the system took place in Puerto Rico and Costa Rica; data collected from the initial deployment was used to track the fluctuation in the population of the coquí llanero (Eleutherodactylus juanariveroi), an endangered species of Puerto Rican frog found only in wetlands near the former Sabana Seca Naval Base on the northern coast of Puerto Rico. Arbimon has since been deployed to monitor species in Brazil, Argentina, Hawaii, and Arizona.

The traditional data collection approach-sending biologists out into the field-"is too expensive and often results in incomplete and limited data sets," Dr. Aide said in a statement on the project. "It is impossible to maintain biologists in the field 24 hours a day throughout the year, and it is impossible to clone expert field biologists so that they can monitor various sites simultaneously."

By allowing constant sampling to be taken over long periods of time with inexpensive gear, those holes in coverage are eliminated, and "biologists can use their time to convert these data into useful information," said Dr. Corrode-Bravo. And since all of the data from recordings is archived, "biologists 20 or 50 years from now will be able to analyze these recordings with new technologies and ideas."