Finally, an egg at N3!

What has been going on with Mom and DM2 this year? RRP staff and volunteers have been monitoring Mom and DM2 at N3 and the hatchery, and we have a pretty good record of their whereabouts with boots-on-the-ground observations and appearances on the hatchery cams. We have documented her standing in the nest for long periods of time, but she didn’t begin incubating until sometime between Robin’s observations on Sunday, March 20 and Dave Kester’s observations on the morning of Tuesday, March 22.

March 28, 2022: D2 in N3. Photo by Mark Worcester.

March 28, 2022: D2 in N3. Photo by Mark Worcester.

Why so late?

Why was she so late? A lot of people asked if she had entered menopause. Like mammals, female birds hatch with a fixed number of ova in their ovaries. How many do bald eagles have? We don’t know, but Waha Thuweeka (a.k.a. Bill Voelker), director of the Sia breeding project, told us that his Golden Eagle Micah was 52 years of age when she laid the egg that produced her daughter Waipi. At 19 years old, Mom is just into Bald Eagle middle age, so menopause shouldn’t be an issue. I briefly worried that DM2 had been replaced, since a new mate can also push egg-laying back, but we saw him enough on the hatchery cams to be sure we were seeing DM2.

We also know that bald eagles have internal circannual clocks that are timed in part by circadian rhythms: the 24-hour cycle of night and day that drives activities like reproduction, molt, and migration. But bald eagles can be thrown off their reproductive cycle if something disturbs them in the period leading up to egg laying, or if their eggs are destroyed after laying. So Mom could have laid an egg that broke or was destroyed, or been thrown off by something that shut down her reproductive activity. Raccoons, chunks of ice, and sticks can all destroy eggs, while ongoing harassment by humans, eagles, and/or other animals can delay nesting activity.

Three-and-a-half weeks later…

It took about three-and-a-half weeks for DM2 to bring Mom back into condition by courting her, bringing food gifts, and copulating with her – about the same amount of time it took Mrs. North to recycle when her lone egg broke back in 2018. Whatever happened, we are happy to report that Mom and DM2 finally have some amount of eggs and we anticipate hatch at N3 on or around April 25. Way to go, Mom and DM2!

Thanks to Robin Brumm, Dave Kester, and Laura Juszczyk for helping keeping tabs on the nest, and to Mark Worcester for the incubation photo! We’re looking forward to Robin’s Day Trips in the months to come.
If you’d like to learn more about eagles and ova, follow this link from last year: