Birding: New technology will provide a better way to track birds

Miniaturization is one of the wonders of our technology. As a case in point, consider the ENIAC, the first supercomputer in 1945. It occupied 1,800 square feet and weighed 25 tons. It could perform 5,000 instructions per second, astounding for its time.

Now consider an iPhone. The device that fits in the palm of your hand can perform billions of instructions per second. It would take about 10 million ENIACs to equal the power of an iPhone.

This trend to miniaturization holds great promise for ornithological research. In today’s column, I want to report on an exciting new technology that I believe will revolutionize our understanding of bird migration.

Thanks to Christmas Bird Counts, eBird records and records from more local birding organizations, we have a good handle on where our migratory breeding birds nest, when they migrate and where they spend the winter. However, our knowledge is very coarse. Rose-breasted grosbeaks nest broadly across the northern tier of the U.S. as far west as Minnesota and into Canada. We know they winter in Central America and northern South America. But where do Maine nesting birds spend the winter? Where do Minnesota birds spend the winter?

One way to answer these questions is to band birds. Birds are captured and fitted with a numbered aluminum band. If the banded bird is recaptured on its wintering grounds, we learn a little about the movements of the bird.

Unfortunately, this technique is inherently inefficient for long-distance migrants. Banding stations are scattered irregularly across the U.S. and Canada and the number of banding stations in Central America and South America is limited. The odds of recapturing a banded bird after a migration is slim. Bird-banding is a much more effective tracking technique for nonmigratory resident birds.

An improvement is the development of radio transmitters. These devices are placed on birds with a harness or glued to the feathers. Each device emits a unique radio frequency. Using an antenna, observers can detect the frequency of a bird with a transmitter. These transmitters are relatively large so are only suitable for larger birds like birds of prey or waterfowl. The range of detection is limited as well. Plus, observers have to cycle through all the frequencies used by their transmitters to listen for particular birds. Having done such a project with American black duck movements 30 years ago, I know this can be laborious.

Satellite transmitters allow tracking over longer distances. However, they are also large and quite expensive.

And now the new developments. Improved radio transmitters are now being produced that are small enough to be put on any bird and even large dragonflies. The transmitter emits a radio signal with a unique frequency, just as before. However, detection stations now can be set up to “listen” for any signal. The stations cycle through all the available frequencies and download records of any bird that passes over.

This new technology is the cornerstone of a new research effort called Motus, which is Latin for movement. The idea is that a network of researchers will set up one or more Motus receivers at strategically placed areas to detect the migratory movements of birds with affixed radio transmitters.

Ideally we will be able to set up “fences” of Motus stations in an east-west direction, spaced close enough to capture any migrant with a transmitter as it moves south or north.

Smaller models are limited by battery size so they have to be programmed to emit radio signals less frequently or we must accept a useful life of less than a year. Expect miniaturization to continue and this shortcoming to be rectified in the future.

This technology will also be useful for tracking the movements of birds while they are nesting or while they are spending time on their wintering grounds.

Herb Wilson teaches ornithology and other biology courses at Colby College. He welcomes reader comments and questions at

[email protected]

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