Environmental consultant Gary Kittleson is on a mission to count the number of frogs at a California marshland. It wouldn't be too much of a task if only he was looking for just any other species.

However, the ones he needs are the California red-legged frogs (Rana draytonii), which can only be found by listening closely to their low croaks in a sea of high-pitched calls from other frogs.

Kittleson was hired by the Land Trust of Santa Cruz County to find out just how many of the red-legged frogs are still left in the Watsonville Slough. This marshland used to be filled with the creatures, but their numbers have dwindled because of over-hunting and habitat loss as a result of human activity in the area. The frogs are now a threatened species.

According to Kittleson, his preferred method to count the red-legged frogs is by listening to the noises that they make. He said that the calls that these frogs make have a lower pitch compared with other species.

He has become so adept at keeping an ear out for the frogs' calls that he can recognize them even while doing something else.

To help make Kittleson's task a lot easier, the Land Trust of Santa Cruz County has teamed up with tech company Conservation Metrics in order to develop an algorithm that could identify the calls of the red-legged frogs.

Through the use of song meters placed around the marshland, Conservation Metrics can collect recordings of various animal sounds and load them into a computer for analysis. The algorithm will run through the recordings and pinpoint which ones are from red-legged frogs. Kittleson will then verify the calls.

Matthew McKown, chief executive of Conservation Metrics, said that tasks such as those normally undertaken by an entire team of scientists can now be carried out by a single person through the help of their algorithm.

"Our whole point is to make conservation better, so we are trying to make it as cheap as possible," he said.

McKown explained that scientists are now using computer programs more extensively to analyze data as part of their studies on threatened animals and their habitats.

He said that equipment such as cameras, satellites and acoustic sensors will soon be used in different parts of the world to monitor the activity of these animals.

Photo: Greg Schechter | Flickr