March 6 notes: incubation begins!
Bald eagles have spectacular courtship displays in the weeks leading up to egg-laying. They soar to great heights, lock talons and cartwheel at dizzying speed to the earth, breaking apart just before they hit the ground. They may chase each other, lock talons, roll together in the air, and continue their tandem flight. These behaviors are part of an annual courtship ritual to strengthen the pair bond and encourage mating. Copulation may take place on the nest or a perch nearby. During the last week, we often heard the eagles vocalizing from the nest tree, but out of view of the camera. Our eagles were discreet, and we didn't observe mating. We suspect the couple spent a romantic weekend somewhere on the coast of Maine!
By the morning of March 6, both birds were at the nest for extended periods of time but still left for varying intervals. Charlie stopped at the USFWS office that afternoon to pick up several eagle carcasses sampled by Steve Mierzykowski, our contaminants biologist. We tuned into this web site and were thrilled to see that the female had resumed incubation posture in the nest. A clear, starry night revealed the adult's white head in that same position long after sunset. Nothing had changed by first light March 7. It seems certain an egg was late March 6!
Management comments: Some observers of nesting eagles get the mistaken impression that they are no longer present when, in fact, incubation is underway. One member of the pair is almost always attending the eggs and out of view. Its prone posture is usually not visible from below. The mate may be ranging widely for food or watching nearby but is also less conspicuous to most. Seasonal privacy near the nest is their priority and a good strategy for those who want to co-exist with nesting eagles. -- Mark McCollough, USFWS, and Charlie Todd, MDIFW