Barn Swallow Bird Migration Tracked with New Tech Techniques

Scientists may be getting some new insight into bird migration by combining new techniques. Scientists have produced more refined estimates of where individual Barn Swallows spend the winter by using methods to both track large numbers and a handful of birds.

Barn Swallows breed in North America, but head south for the winter to a broad area that encompasses most of Central America, the Caribbean and South America. In this latest study, researchers wanted to find a better way to determine where within this range Barn Swallows were spending their winter months.

So what did they do? The researchers combined isotope analysis with a geolocator study. The isotope analysis involved sampling the isotopes of elements in birds' feathers for clues about where the birds were when the feathers grew. The geolocator study fitted birds with small devices that calculated and recorded their location based on daylight, the catch being that the birds had to be recaptured when they returned in order to download the data.

The researchers looked at the isotope analysis to see whether a bird was on the coast or inland. In addition to collecting feathers from 208 Barn Swallows for isotope analysis, the scientists were able to recapture 14 swallows to which they had attached geolocators. This helped confirm that the locations inferred from isotopes were accurate.

So what did they find? Most of the birds were wintering in open agricultural and savanna regions outside of the Amazon basin.

"I think the study nicely demonstrates the need to get away from the dichotomous thinking of pitting one technique against another," said Keith Hobson, one of the researchers, in a news release. "All are useful and all have their strengths and weaknesses if you take the time to understand them."

The findings are published in the journal The Auk: Ornithological Advances.

Related Articles

Crows Caught on Camera Building Special Hook Tools

Why Birds Don't Go Grey as They Get Old: How They Keep Vibrant Colors

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).