Attempted supplementation of the relict wild Eastern population of northern bald ibis in Syria with Turkish semi-wild juveniles

Summary

The Critically Endangered eastern population of northern bald ibis, rediscovered in Syria in 2002 with seven adults, had collapsed to just three birds by 2010 when only one breeding pair returned from migration. Following earlier failed attempts to integrate captive birds with wild populations and expert advice that supplementation with juveniles was a last resort, the RSPB and an international consortium including Turkish authorities obtained two 2010-hatched juveniles from Turkey's genetically similar semi-wild Birecik population. The juveniles, plus four adults intended to found a Syrian captive breeding program, were transported 250 km to Palmyra in June 2010 and moved into a temporary pre-release aviary near a wild feeding site to encourage contact. The three remaining wild birds showed interest within a day, but two left on migration almost immediately, prompting an early release of the juveniles, which then followed the one remaining wild adult female and a wild juvenile on migration just one day later, traveling 1,900 km to Saudi Arabia over two weeks at up to 350 km per day. Beyond that point the group separated: the wild adult continued to Ethiopia, while the wild juvenile died in captivity and both released juveniles are believed to have died in southern Saudi Arabia six to eight weeks after departure, based on satellite tag mortality signals that could not be physically confirmed. Major difficulties included a compressed acclimatization window and unrecoverable tracking tags. The project rates itself Partially Successful, since the birds integrated with wild individuals remarkably well but ultimately did not survive to contribute to the population.