The rare northern bald ibis could soon be extinct as a result of the Islamic State takeover of the ancient Syrian town of Palmyra, according to a report by the BBC on Monday. Three extremely rare ibises were kept in captivity in the central-Syrian city. Their condition has been unknown since the caretakers were forced to flee the town after Islamic State militants stormed the city on May 20. A search is also underway for an important fourth, female bird, named Zenobia. The Society for the Protection of Animals in Lebanon said that she is the only one of the birds to know the ibises's winter migration route to Ethiopia. A $1,000 reward is being offered for anyone with leads on the Zenobia's location. They say that without her, the birds kept in captivity would not be able to be released. Asaad Serhal, who heads the SPA in Lebanon, expressed his worry. "Culture and nature they go hand in hand, and war stops, but nobody can bring back a species from extinction."The northern bald ibis was considered extinct until 2002 when a small colony of seven birds was found close to Palmyra. They were put into captivity for protection, but the numbers of the rare ibises continued to dwindle.Reuters contributed to this report.