The northern bald ibis was once widespread across the Middle East, northern Africa and the European Alps but there are now just 13 left in Syria and 100 breeding pairs in Morocco.
Scientists from the Royal Society for the Protection of Birds (RSPB) and BirdLife Middle East hope to locate where the ibis go to for the winter and discover why so few birds come back.
The birds are expected to head south towards Saudi Arabia and Yemen, or even as far as Eritrea.
The northern bald ibis is classified as critically endangered by the IUCN-World Conservation Union and its numbers have declined rapidly due to habitat loss, human disturbance, hunting and pesticide poisoning.
There are now only two populations left in the world - the small number in Syria and the ones in the Souss-Massa National Park near Agadir in Morocco.
