Deceptive woodpecker uses mimicry to avoid competition

11-Aug-2015
Deceptive woodpecker uses mimicry to avoid competition

Central Ornithology Publication Office



IMAGE: Dryocopus galeatus (left) appears remarkably similar to Dryocopus lineatus erythrops (center) and
Campephilus robustus (right), but it's only a distant relative.



Credit: K. Zimmer and R.J. Moller


Birds of a feather may flock together, but that doesn't mean they share a genetic background. Though birds were first classified into groups primarily based on appearance, research forthcoming in The Auk: Ornithological Advances by Brett Benz of the American Museum of Natural History, Mark Robbins of the University of Kansas Biodiversity Institute, and Kevin Zimmer of the Los Angeles County Museum of Natural History demonstrates that this method isn't necessarily accurate: in a group of very similar-looking South American woodpecker species, genetic analysis has now shown one to be only a distant cousin of the others, in an intriguing case of visual mimicry. By copying the appearance of larger, socially dominant woodpecker species, it reduces the aggression and competitive interference that it receives from them and has more access to food resources as a result.

The most familiar type of mimicry typically involves warning or "aposematic" coloration, in which a harmless species apes the color patterns of a dangerous or unappealing one to avoid predators; a famous instance is the Viceroy butterfly, which shares the striking colors of the more noxious Monarch. By contrast, the Helmeted Woodpecker (Dryocopus galeatus) represents an example of a different and less well understood form of mimicry, known as interspecific social dominance mimicry or ISDM.

The shy and little-known species shares the red crest, black back, and barred underside of two larger woodpeckers Dryocopus lineatus and Campephilus robustus, all of which occupy the same habitat and share similar food preferences. The Helmeted Woodpecker's similarity in appearance makes the larger, more dominant woodpecker species less likely to attack it, due to the costs of aggression between members of the same species. Though they had been previously classified in Dryocopus due to the remarkable similarities in their appearance, genetic analysis by Benz and his colleagues suggests that the Helmeted Woodpecker is actually not closely related to other Dryocopus woodpeckers at all and belongs in a different genus, Celeus. An independent group of researchers using the same data recently reported similar results in a paper published in the Journal of Ornithology.

"Co-author Mark Robbins and I had just finished a phylogenetic study examining species limits and vocalizations in Celeus woodpeckers when Mark, who was attending a meeting in Brazil, had the opportunity to observe a Helmeted Woodpecker at Intervales State Park," according to Benz. "Upon hearing the bird vocalize, Mark was stunned that its call sounded nothing like Neotropical Dryocopus, and immediately knew we needed to examine its taxonomic status in the context of our recent Celeus study given that the Helmeted Woodpecker calls were most similar to several other Celeus species. Upon returning from Brazil, Mark consulted with co-author Kevin Zimmer, who had independently arrived at the same conclusions about the Helmeted Woodpecker belonging with Celeus, based on his behavioral observations spanning 20 years of fieldwork in Brazil." As Benz puts it, "The Helmeted Woodpecker is basically a typical Celeus in Dryocopus clothing."

More:
http://www.eurekalert.org/pub_releases/2015-08/copo-dwu081115.php