Polygamy observed in trio of great horned owls

A trio of great horned owls has been found to be engaging in a polygamous relationship according to an ornithologist with Bird Studies Canada. The finding has been reported by Doug Main with National Geographic.

Great horned owls are notoriously territorial, which is why finding two females building nests next to each other was so unusual. Also unusual was the single male bringing food for both of the females as they sat on their eggs. Such behavior, Christian Artuso (with Bird Studies Canada) suggests, likely indicates that the male mated with both females—an example of polygamy. If true, the observation would be the first record of it.

The birds were discovered outside of an office window by Jim Thomas at the Desert Research Institute in Nevada. He alerted the Nevada Department of Wildlife's David Catalano, who is also an ornithologist. Upon viewing the birds, Catalano described the situation as "very, very odd." Not only are great horned owls very protective of their territory, they are also believed to be monogamous. This is the case for most raptors, Main notes, likely due to the huge demands on the male to feed both himself and the female while she is nesting. To follow what was going on, technicians at the Institute set up a webcam to allow others to see the unique situation, as well. Main reports that the owls became quite popular.

But there was more oddness to come. For unknown reasons, none of the eggs for one of the hens hatched. Instead of leaving, that hen simply became a second mother to the owlets that hatched to the other hen.

Catalano suggests the odd behavior could be due to the females being related. It could be a mother/daughter relationship, he notes, or they might siblings. No testing of the birds was done, so he cannot say for sure. Nor was it possible to determine if both hens had actually mated with the male. Staff at the Institute reported that the two hens did at times have tussles, but managed to raise two owlets quite well. One has reportedly already left the nest.

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