On how the playback resurrected the Scarlet-rumped Tanager and more…
Finally the 2018 AOS supplement is out! This is what many birders (I hope is not just me) wait for months to reveal what are the official “new species” to the list and what we have lost in terms of lumps of two species previously thought to be different. This issue has some interesting changes and some other changes that seem senseless and very redundant. But the appreciation of the actual changes can only be fully understood if we go deeper on the background of what happened here.
After reading word by word the new supplement I found out many of the actual changes have something in common. The use of a new technique to “ask the birds themselves” if they can recognized the call of an isolated population in where researchers never notice any difference. By using playback to test birds’ reactions to recordings of their relatives, observing whether or not they approached the speaker. As says Freeman (co-author of the research) to a note in the The Auk blogspot “these populations look the same—they have similar plumage and are similar in size and shape—but assuming that populations that sing differently tend not to interbreed, this means that species-level diversity in the Neotropics is underestimated.”
And sure it is underestimated, just by mixing the technique of the playback and then backing up with a bit of DNA tests they found out 12 new species for the neotropics. From all these new recognized species, one was found in Costa Rica and some of the other news also come thanks to this amazing research. Below I will explain in detail this and other noteworthy corrections you have to make to your bird book…
The resurrection of Scarlet-rumped Tanager.
So no more Passerines and Cherries Tanager… they did the playback experiment on this bird and found there were not enough discrimination on individuals of the pacific with the individuals of the Caribbean of Costa Rica to actually tell them apart as separate species. So after some more DNA experiments to reinforce the playback study they realized they are in fact the same species… which mean they were divided by the Talamanca mountain range only less than one million years ago (sorry, not enough to be a different species). So back to the old Scarlet-rumped Tanager as they decided to respect the original name… a much more appropriate name and one that brings back old memories about birdwatching in Costa Rica when I was younger.
"Is this a Cherrie's Tanager or Passerini's Tanager?" Who cares now... you wont hear this question anymore as they are all the same. Scarlet-rumped Tanager from Carara National Park area.
Welcome home Chiriqui Foliage-gleaner.
Back to the experiment of the playback again…. Freeman and Montgomery conducted the playback experiments on 15 territories of Buff-throated Foliage-gleaner in the pacific slope of Costa Rica and western Panama and 14 territories of Buff-throated Foliage-gleaner in the Caribbean slope of Costa Rica and Panama. Each playback experiment measured whether populations fail or not to be attracted by the song from the other population.
Populations of Buff-throated Foliage-gleaners from the Pacific and Caribbean slopes of Costa Rica respond strongly to local song but essentially ignore song from their relatives across the mountains. This suggests that vocal differences constitute a strong premating barrier to reproduction between these birds, and is consistent with the genetic data that indicates that, despite living quite close, these populations last shared a common ancestor around 3 million years ago and that is fair enough to do the opposite they did with the Cherries and Passerines tanagers and as conclusion we have a new endemic; Chiriqui Foliage-gleaner
Here you can hear a Buff-thorated Foliage-gleaner at Braulio Carrillo and here the call of the brand new endemic, Chiriqui Foliage-gleaner at Piedras Blancas. Please remember this subtle diffe