The adult males, known as Dashik and Yehuda, built a nest last year and set-up home together. In the spirit of gay liberation, they openly and energetically mated, but failed to produce a single egg.
Then, as an experiment, Israeli zoologist Shmuel Yidov took a day-old vulture chick that had been hatched in an incubator, inserted it carefully inside a swan's egg and slipped it into the nest. Fooled, the pair took turns to sit on it and warm it until it hatched again.
Dashik and Yehuda then reared their baby. "They did a great job," said the zoo's spokeswoman, Sigalit Dvir. "They shaded him on hot days, they brought him water from a pond, they fed him, they stopped him falling from the nest."
This summer the adoptive parents have done it again. The young birds were taken to a station on the Carmel mountains south of Haifa, where Israel's Nature Protection Society conditioned them and returned them to the wild.
Sixty years ago, the Holy Land boasted about 1,000 breeding pairs of griffon vultures. The population today is down to about 70 pairs. In the mid-Nineties, they were threatened with extinction in Israel by cattle farmers trying to poison packs of wolves on the Golan Heights. The wolves did not take the bait, but other animals did. The vultures picked at their carcasses.
Over the past decade, the Nature Protection Society has hand-reared 80 nestlings. Vultures generally lay only one egg a year, but if it is removed from the nest they lay a second. So the conservationists take the first egg and incubate it, and a second egg is assured.
The trouble is that hand-reared vultures find it harder to adjust to nature. They look for human beings to feed them. "It's better," Shmuel Yidov explained, "for vultures to take care of vultures." Gay or straight.