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Lines between two sparrow species blurred in New England

"Both of these birds are high conservation priorities in the Northeast," researcher Jennifer Walsh said.

By Brooks Hays
A saltmarsh sparrow. Photo by Wolfgang Wander/GFDL/CC
1 of 2 | A saltmarsh sparrow. Photo by Wolfgang Wander/GFDL/CC

DURHAM, N.H., Aug. 31 (UPI) -- New research in New Hampshire suggests interspecies breeding among marsh sparrows is common, and hybrid offspring don't take on a uniform, easy-to-spot appearance.

Lines between bird species are often blurry, as a close relatives are known to mate when ranges overlap.

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A new study by scientists at the University of New Hampshire suggests interbreeding is particularly prevalent among two sparrow species found along the coast of New England, the saltmarsh sparrow and Nelson's sparrow.

Hybrid birds are the result. But as the new study -- published in the journal The Auk: Ornithological Advances -- shows, the hybridized sparrows and their offspring are quite hard to pick out. A re-examination of sightings data suggests ornithologists have failed to account for their significant presence.

DNA analysis showed that some 50 percent of sparrow specimens identified as either purely Nelson's or saltmarsh during field research in Maine, New Hampshire and Massachusetts, were actually the descendants of hybrids.

"Our findings show that hybridization can lead to complex combinations of plumage traits making hybrid identification difficult by appearance alone," researcher Jennifer Walsh explained in a press release. "This also means that it is challenging to monitor the abundance/distribution of hybrids within natural populations without collecting genetic data."

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"Both of these birds are high conservation priorities in the Northeast, and hybrid identification and monitoring can aid in management and conservation initiatives for saltmarsh and Nelson's sparrows," Walsh added.

The researchers say their findings should serve as example to other ornithologists conducting research in hybrid zones. Examining appearance and morphology alone is not enough to accurately count species numbers.

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