A potential breeding site was identified in Afghanistan but now the first actual site has been found in Tajikistan.
The 2006 bird was trapped in Thailand and two years later the same bird was recaptured, as was another in a different part of Thailand.
Last year researchers believed they had discovered a breeding site in Afghanistan, after catching 15 birds which DNA analysis confirmed. They were not able to confirm that the species was breeding in the area, according to internationally agreed criteria.
However another set of researchers discovered the species at three different sites in the Gorno-Badakhshan region of Tajikistan.
According to Manuel Schweizer a PhD student at the Natural History Museum in Bern.
One of four adult birds caught in Vezdara displayed a large brood patch, suggesting that it was breeding
Also in Vezdara, two Acrocephalus warblers were observed around a group of bushes on 18 July and could be caught later and three rectrices on one tail side were taken for DNA analyses.
On the 19th, they were again observed around the same bushes, this time missing rectrices on one side of their tails and feeding two fledglings.
The fledglings were still extremely weak flyers and hardly able to fly from one bush to another.