for National Geographic News
A giant crocodile in South Africa is revealing its secret whereabouts through instant messages to the cell phone of the scientist studying its habits.
At regular intervals a message appearing on the cell phone of scientist Hannes Botha gives the code name of the crocodile, NGCRC1, and its longitude and latitude and the date and time of the reading. The message comes from a cell phone and a GPS (Global Positioning System) device fitted into a five-inch (12-centimeter) cylinder fixed to the bony scales behind the head of the 13-foot-long (four-meter) animal.
The NG in the code name stands for National Geographic, signifying the Society's involvement as a sponsor in the project.
By mapping the crocodile's movements in this way, Botha wants to get a better picture of the creature's movements within the 1,600-hectare Flag Boshielo lake and the river that feeds into it about 125 miles (200 kilometers) north-east of South Africa's capital Pretoria.
By gaining a better understanding of the habits of the crocs in the area, he hopes to prevent development at their regular calling spots along the lake and riverbanks and so reduce the potential for conflict with humans.
Botha believes the information could also be useful in regulating crocodile numbers in closer accordance with the habitat's carrying capacity.
The leader of the project is Wouter van Hoven of the University of Pretoria's Centre for Wildlife Management. He says an important aspect of the study is to establish the reasons for the high concentration of crocodiles in that particular lake, while another lake nearby which is ostensibly equally suited and situated in a nature reserve, has no crocodiles.
"We want to see what the powers at play are—why the crocodiles seem to prefer this area and not the other," said van Hoven. "Crocodiles are not a threatened species, but we need this kind of information to take a balanced approach to nature conservation," he said.
Croc Studies Require Special Technology
GPS technology is widely used on land-based animals for studying their movements. It is fitted on a collar, and, being on land, it is fairly easy to keep track of the animal.
"With crocodiles it is far more difficult," said Botha.
"The device has to be above or just below the water surface for its signals to be received, and a large crocodile like the one we are tracking can stay deep underwater for up to two hours. Thus, you get a fix on it, and then it disappears, only to resurface much later and a considerable distance away.
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