Those gibbons sure can wail

Birds are not the only animals that communicate by singing—gibbons, apes more closely resembling monkeys in size, sing to strengthen social relationships, announce their territory and find a mate. Crested gibbons in the genus Nomascus live in the Asian rain forests of China, Laos, Cambodia and Vietnam and sing for a specific purpose. “The songs are specifically adapted to travel over long distances through the dense vegetation of the rain forest by concentrating all of the energy into a single frequency, similar to the calls used by rain forest birds,” wrote Jennifer Welsh in a Live Science article. The coloration in gibbons varies by individual, making it difficult for researchers and conservationists to distinguish between species. But as Sarah Zielinski reported in yesterday’s Surprising Science post, scientists from the German Primate Center in Goettingen examined the songs of seven species of crested gibbons and found that each species had its own distinct dialect. “The researchers found that the songs of the two northern species, N. nasutus and N. concolor, were significantly different from those of the four southern species, and the songs of the four southern species were all subtly different from one another. And the more closely related two species or populations songs were, the more alike was their mitochondrial DNA.” The findings, said the researchers, could help to monitor gibbon populations through song, as opposed to visual, recognition. In addition, continued Welsh, “[t]he gradation of song similarity between the northern and southern populations supports the idea that the genus began in the north and migrated toward the south.” Read more at “Crested Gibbons Sing in Different Dialects.” Photo Credit: Tim...

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Antbird songs converge while other traits don’t

Convergent evolution of large functional traits is not uncommon in nature; consider that wings have evolved in several lineages of animals to broaden niches that animals can fill.  But more specific convergence, especially in sexual and territorial signals, is rare at best and stirs controversy in the scientific world. On the surface, it would seem that if two species converge in their signals, it would lead to crossbreeding and antagonistic interactions. But in a paper online today in Evolution, Joseph Tobias and Nathalie Seddon of the University of Oxford show that for two species of antbirds in South America, convergence has nevertheless occurred. Said Tobias in a press release: In effect, the territorial songs of these birds are more or less interchangeable in design and function. Given that they last shared a common ancestor more than 3 million years ago, it is almost equivalent to humans and chimpanzees – which diverged around 5 million years ago – using the same language to settle disputes over resources. Tobias and Seddon used playback experiments to test the reactions of the warbling antbird and the yellow-breasted warbling antbird to songs of the other species. The birds reacted to both songs similarly, treating the songs of each species as equally threatening. The most interesting piece, however, was that Tobias and Seddon also found that other non-territorial signals, such as plumage coloration and mating calls, were highly divergent. The fact that these traits are so different between the species could help prevent crossbreeding or unnecessary confrontation. Read the paper at Evolution (subscription required). Tobias, J., & Seddon, N. (2009). SIGNAL DESIGN AND PERCEPTION IN ANTBIRDS: EVIDENCE FOR CONVERGENT EVOLUTION VIA SOCIAL SELECTION Evolution DOI:...

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Skylarks don’t talk to strangers…or wanderers

Bird songs are among the most complex and fascinating forms of animal communication. Tiny differences in bird songs can often result in “dialects”, where populations of the same species have slightly different variations on the same songs. In a study out today in Naturwissenschaften, ornithologists have taken it a step further. Some skylarks can not only differentiate among songs of neighboring  birds, but also match these songs with their territories and punish birds who stray from their own “property.” Elodie Briefer, a postdoc at Queen Mary University of London, and her colleagues studied skylarks in fields surrounding the University of Paris. They found that familiar skylark neighbors are tolerated if they stay in their own territory, but — not surprisingly —  skylarks with songs they don’t recognize as from the area are attacked if they intrude too close to the nest. But they also used playback experiments to observe the birds’ reactions when they heard the song of a familiar skylark from different directions. Neighboring birds who strayed from their own territories were also treated as intruders. The songs of neighboring skylarks share more syllables with each other than with the songs of strangers. Briefer said in a statement: This may have evolved because it is safer for the birds to live close together, but they need a way to keep intruders out. By sharing a local dialect in their song, they can keep an ear out for other birds that live nearby and kick any strangers out of the neighbourhood. Read the full paper at Naturwissenschaften (subscription required for full text), and check out Briefer’s video below of skylarks responding to a stranger’s song. Briefer, E., Aubin, T., & Rybak, F. (2009). Response to displaced neighbours in a territorial songbird with a large repertoire Naturwissenschaften, 96 (9), 1067-1077 DOI:...

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