Animal Evolution: Helmeted Woodpecker Mimics Its Larger Competition

An otherwise timid South American woodpecker has evolved into a larger, tougher bird to defend against other feathered bullies. The Helmeted Woodpecker (Dryocopus galeatus) lives in the Atlantic forest among two larger species, known as the Lineated (Dryocopus lineatus) and Robust (Campephilus robustus) woodpeckers.

"Because of this, it has the advantage of foraging in the same areas as the birds it's mimicking, with those birds not being aggressive to this smaller woodpecker," Mark Robbins, co-author and ornithology collection manager with the University of Kansas Biodiversity Institute, said in a news release.

According to their study, the Helmeted Woodpecker has deceived both competing woodpeckers and researchers who have misclassified them based on their visual mimicry.

"It's very similar in pattern to these other woodpeckers," Robbins explained in the release. "In the 1980s, a monograph called 'Woodpeckers of the World' used museum specimens to assume relationships, and that has misled ornithologists across the board. Looking only at plumage has misguided us again and again."

Robin and two colleagues conducted a genetic analysis of the bird to determine if it actually should belong to the genus Dryocopus, which was suggested by the bird's appearance would have it. However, based on its DNA, they later concluded that the Helmeted Woodpecker belonged to the genus Celeus.  

"Background genetic work on placement of this bird was performed using tissue from toe pads from specimens at the L.A. County museum that had been collected over 60 years ago," Robbins said in the release.

This means that the bird was able to mimic the appearance of the Lineated Woodpecker to increase its foraging success, the release noted.

However, according to the researchers, the Helmeted Woodpecker faces the additional threat of deforestation due to soybean and sunflower farming.

"It's only found in southeastern Brazil, eastern Paraguay and extreme northern Argentina," Robbins said in a statement. "Much of that forest is gone. It's a biome that's been particularly degraded, and this woodpecker had declined considerably due to deforestation of the Atlantic Forests. It's threatened, has been misplaced phylogenetically and is mimicking bigger, more aggressive birds."

Their findings were recently published in The Auk: Ornithological Advances.

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