How Micro-Transmitters Help Solve Nature's Riddles

• research
• insects
• animals

Chasing insects in airplanes is just part of Martin Wikelski’s job description as director of migration research at the Max Planck Institute for Ornithology. In an attempt to discover migration strategies shared by various flying creatures, the German researcher glued 0.3-gram radio transmitters onto the thoraxes of 14 dragonflies and followed them in a single-engine Cessna. The bugs’ survival techniques became clear as he observed individual insects day after day: They refuse to fly when conditions are too windy; they schedule rest days and travel only during warm daylight hours.

Hanging a battery-powered transmitter on the ear of a 500-pound grizzly bear is one thing; installing a similar rig on a lightweight bird or insect is harder. In recent years, electronic transmitters have become miniaturized enough to fit on even the most diminutive creatures. Researchers can assign a frequency or identification number to each tag so that individual animals can be identified. Scientists are using more advanced tracking devices to gather other kinds of data. Proximity tags the size of a quarter, created by a team at the University of Washington, exchange their unique codes when they come within a preset range, then store the event as an “encounter.” The data is stored on the base station until a field assistant retrieves it. The information is then used to create models of which animals are hanging out with each other. This is especially useful in charting the movements of sick animals or discerning how offspring learn behavior from their elders.

Micro-Transmitters Photo Gallery
+ CLICK PHOTOS TO ENLARGE: Biologist Martin Wikelski glues lightweight tracking devices [1] onto the thoraxes of migrating insects [2] and then tracks them with receivers [3].

Researchers Solve Nature’s Riddles With Microtransmitters

Salmon Superhighway: Atlantic Salmon Federation biologist Fred Whoriskey is tracking fish migration using arrays of receivers moored to the seafloor to tally passing fish implanted with “sonic pingers.” He found a salmon superhighway between Newfoundland and Labrador where fish gather en route to foraging grounds near Greenland. “I think this research is showing us that there’s a social dynamic to fish populations that we’ve been underplaying,” Whoriskey says.



Sleepy Snakes: Biologist Jonathan Mays surgically implanted radio transmitters into black racer snakes in Maine. He discovered that females travel up to 3 miles to lay eggs and that the snakes hibernate beneath open grasslands, not in wooded ravines as previously thought.



Social Sparrows: A team of scientists at the University of Washington is outfitting song sparrows with tiny microprocessors and transceivers. As these Encounternet tags interact with one another, they document the social interactions between the birds.

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