We have finally solved the mystery of the alien egg in the grey goose nest, whose photo featured in the April newsletter.

After it hatched, it was clear that this was an Egyptian goose egg and not a peahen egg, as we had previously thought. According to Prof. Yoram Yom-Tov, in conversation with Dr Ron Elazari, it seems that among ground-nesting birds, whose chicks are precocial, no mechanism has developed for preventing parasitism, such as the ability to identify an alien egg, due to the relatively low energetic cost of raising such chicks in comparison with raising altricial chicks.

The two groups of eagle-owls, which are located side by side in the northern part of the Zoological Garden, were once considered as two populations or sub-species of the species Bubo bubo. However, about five years ago they were reclassified as different species – the northern population is called the Eurasian eagle-owl (Bubo bubo) and the desert population is the Pharaoh eagle-owl (Bubo ascalaphus). Some of these eagle-owls have been with us for the last 40 years (!), having originated in our old Zoological Garden in Abu Kabir.

Photo: Oz Rittner

Eagle-Owl, Photo: Oz Rittner

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