We're getting a lot of questions about how the owl could have gotten past Mom and Dad in Eagle Valley. Are Mom and Dad bad parents? Unobservant? Poor protectors? No. However, they are primarily diurnal birds. Although we've seen bald eagles awake and active after dark, they tend to sleep at night: http://www.ustream.tv/recorded/47617300. In contrast, owls are outstanding nocturnal hunters. They fly silently, have very large, tubular eyes with an abundance of light gathering rods, and possess exceptional hearing thanks in part to their facial disks and in part to ear hole placement. The owl could have landed on the nest before either parent was aware of it. When Mom reacted, she may have uncovered her young and unintentionally made them available to the hunting owl.
On February 25, an owl jumped on Mom in Decorah. While she wasn't injured and there were no young in the nest, the video below provides an example of just how silent they can be in flight. Thanks to David Lynch for finding it. If you'd like to read more about owls, click here: http://goo.gl/W0pL0K
We've also been asked why an owl would target an eagle's nest. Owls eat a wide variety of prey and the nest was a potential source of food, adult eagle or not. The eagle nest invaders we've seen include owls, raccoon, red-tailed hawks, squirrels, starlings, sparrows, and mice. Some of them were drawn by eggs and young birds, others wanted nestovers, and one hungry red-tailed hawk attempted to steal prey from Dad in 2011 (clearly visible at 2:15 in the video): http://youtu.be/VbrBUMS_ZPc. Many animals are willing to risk approaching the nest for a meal. Sometimes they are successful and sometimes, like the hawk at Duke Farms last year, they die in the attempt (warning: some readers may find this video disturbing): https://www.youtube.com/watch?v=QqooTTD8sn4
In short, the parents at Eagle Valley are not deficient or lax. I've watched the footage a number of times and I can't hear an owl coming (or see anything). The nest was targeted by a specialist nocturnal hunter who was able to get into the nest before either of the adult eagles were aware of it. We hope the remaining eaglet survives until fledge.