But Dr Richard Griffiths and Bela Tiwari of Oxford University have devised a technique to sex the endangered bird from minute samples of DNA taken from moulted feathers.
"We have managed to reunite most of the lost people with their families, but we still have about 150 people waiting, " says Mr Tiwari's son, Umesh Tiwari, who is taking over the running of the camp from his father.