Monitoring Crabs from Space with GPS Tracking9 May 2013
GPS tracking reaches new heights with the ability to track free-roaming land crabs on Christmas Island.
Researchers from the Max Planck Institute for Chemical Ecology in Germany are studying the long-term movements and migration habits of the coconut crab (Birgus latro).
The Coconut crab is a crustacean living on various tropical islands in the Indo-Pacific, prominently on Christmas Island. With help from scientists at the Zoological Institute at the University of Greifswald, researchers from the Max Planck Institute is incorporating advanced GPS tracking technology in hopes of monitoring the crab’s behavior.
The Burgus latro crab is the largest land-living arthropod in the world at approximately 4 kg. It is appropriate nicknamed the giant robber crab and can live up to 60 years. The robber crabs have a leg span of approximately 3.3 feet and belong to a group of exoskeleton animals, including arachnids, insects, and crustaceans.
Christmas Island in the Indian Ocean is where the crab monitoring study took place, due mostly to the fact that is a mostly undisturbed population of the coconut crab. 55 male robber crabs were outfitted with GPS tracking tags and were monitored between 2008 and 2011. The GPS tracking devices provided researchers with over 1,500 days of data which included their normal, everyday activity. Many of the crabs had the GPS tags equipped for 3 months.
The GPS data revealed short and long distance movements, including migration from the Indian Ocean coast to the inland rainforest on Christmas Island. Monitoring included not only migration but saltwater drinking, foraging, and mating. One interesting fact that arose from the data was that these robber crabs are able to home across long distances; many of the crabs traveled up to 3 miles in search of mates, food, and saltwater.
The GPS tags were programmed so that they would monitor and record the crab’s positions for several months in intervals of an hour. They also had accelerometers which would record the crab’s movements in various directions which further explained the depth of their activity.
In order to not disturb the crabs being monitored, scientists downloaded the data once a week with a radio link that had a 200-meter range. The radio impulses allowed for localization of the robber crabs with a wireless connection. This is the same technology used for studying bird migration, sharks, manta rays, turtles, and other wildlife.
From the study, scientists and researchers were able to learn more about the Burgus latro crabs including where they migrate, how long they travel for food and water, everyday behaviors and mating habits.
If it wasn’t for modern GPS technology, the Burgus latro crabs would still remain a mystery to scientists. GPS technology continues to be the leading research tool for monitoring crabs and other wildlife.
Stay tuned for more posts on how GPS tracking technology is being used in wildlife conservation.