No easy answer for these often asked questions. How do bald eagles choose their mate? Does the female or male make the decision? Is there competition? How can they recognize each other from such long distances away? While the subject of mate selection has been well studied in many species, I have not found any published studies of mate selection by the bald eagle, and my colleagues at the Center for Conservation Biology have the same answer that I have – I don’t know!
However, there are several clues even if we don’t know for certain. Charles Darwin was the first to suggest in his 1859 The Origin of Species that sexual dichromatism – one sex brightly colored the other drab – played a role in choosing a mate. For the most part his theories were rejected for many years. I expect that most viewers of the WVEC web cam at Norfolk Botanical Garden have seen nature programs on television of brightly colored males dancing or displaying in front of one or more drably colored females as part of the mate selection process. Both the male and female bald eagle look alike so is color a factor? Probably not. Perhaps size is a factor since the male is always smaller. How about display? Bald eagles are well known for their “courtship flights” sometimes called sky-dancing. Locking talons and tumbling down together is often observed. In December 1992 the then only known pair of bald eagles in Virginia Beach locked talons and fell into Atlantic Ave where they were covered with a blanket by a motorist until animal control officers arrived to get them unlocked. Neither eagle was injured and flew off. Is there competition? A few years later three bald eagles fell out of the sky locked together into a mans yard in Thoroughgood in Virginia Beach as he worked in his yard. One eagle flew off immediately, one flew off after resting a few minutes, and the other waited until I got there with a reporter from the newspaper. Was it two males after the same lady? Two ladies after the same guy? Don’t know, but maybe. Who makes the selection? Most studies have determined that it is the female, however that is not always the case. One study of barn owls in Europe determined that the male made the selection based on very minor color differences in breast feathers on the female. Birds are highly visually sensitive, but sounds can also be a factor in identification. I have been in hugh colonies of several species of penguins and they locate each other by the sounds they make. Visitors at Norfolk Botanical Garden have noticed that the pitch of the voice of the male and female is different. Is this another factor in mate secection? Possible!
So where does that leave us as far as an answer? Perhaps ornithologist and professor of biology Geoffrey E. Hill states it best in his book Bird Coloration – A simple visual signal that says “I am a male” or “I am a female” says it all.