Scientists have uncovered as many as twenty-one new species of tropical bird by sophisticated analysis of the songs that they sing. The researchers were intrigued by why birds that seemed almost identical to one another would not respond to the calls of other birds … a key factor in how they breed.
And so they set up a series of experiments where they would ask the birds themselves and try to identify which were the same species, and which might be something different. First, they analysed more than a thousand birdsong recordings for seven different variables to identify unique calls. Then, they used playback experiments to test how birds would react to recordings and whether they would approach when they heard a song.
To do this, they put wireless speakers in the bird’s natural habitat, played the call, and watched to see how close they came and how they responded. They found that some of the birds failed to recognise each other’s songs despite the fact they were up until now considered the same species. The research team reckon that 21 pairs could now be considered separate species based on what they called “song discrimination”. The birds they looked at were found in Panama, Costa Rica and Ecuador – all three of which are considered as international hot-spots of biodiversity.
Benjamin Freeman of the University of British Columbia explained: “it is abundantly clear to anyone familiar with the amazing diversity of Neotropical birds that there are many cases where populations that sing very different songs are classified as the same species. These populations look the same – they have similar plumage and are similar in size and shape – but assuming populations that sing differently tend not to interbreed, this means that species-level diversity in the Neotropics is underestimated.”