Chicago Peregrine Falcon Blog

At about 11am yesterday morning, my boss Carl came into my office.

“Hey,” he said. “I was just outside on the north side of the building and I noticed a broken egg right under the peregrine nest. Maybe you want to go check it out?”

Indeed. I grabbed my things and hurried over to the bird department to let Mary know. About five minutes later, we stood outside on the stairway, looking down at a big egg splat. The egg had basically disintegrated on impact, but we managed to find enough shell to verify that it belonged to a peregrine.

After collecting as much debris as we could and taking a number of photos for documentation, we backed off to search the building for a perched peregrine. I got my camera out and pumped it up to full zoom, managing to capture a photo of the very top of a peregrine head back in the shadows of the nest area. The other one wasn’t around.

We watched for a few minutes and then went back inside the museum. A half hour later, Carl came back into my office. “I think there’s another egg on the ground,” he said.

Mary comes into work at Oh-God:30, so she’d already gone home by this time. I went out on my own and found a much fresher egg splat surrounded by the remains of a shattered peregrine egg shell, a few prey remnants and some cobweb/dust balls. I used tweezers to pick up the shell and baggied it all. Next, I collected a very fresh bird wing – juvenile red-winged blackbird – and popped it in another baggie. I tried to collect some of the other feathers in the crash zone, but found they’d been glued to the marble by the rapidly drying egg yolk. Finally, I used a razor blade to get some of the congealed yolk off the marble stairs and into a small cryotube. In the process, I got a lot of egg on myself, which is when I noticed that the egg didn’t smell so great. Hmmm.

After I’d finished collecting what I could, I backed up and raised my binocs. A peregrine stood in the shadows in the very same place as last time. As I watched, the male came swooping in, vocalizing. He went back into the shadows of the nest and the two birds interacted a moment before he flew off and she closed her eyes again.

I started to get just a touch worried that something was wrong with her. Something about the way she stood and her lack of animation seemed off. Time would tell.

Unfortunately, no magical elves up in my office were finishing my work, so at last I had to go inside. On the elevator ride up, it occurred to me, and I believe a few other people in the car, that the egg really did smell decidedly “off”. I noticed I had yolk on my pants.

Throughout the remainder of the day, I went down to check the nest site on the hour. I did not see any other egg casualties, but I again noticed that the female had not moved at all.

At 4:30pm, I left for the day and spent a few minutes watching her. She’d shifted position slightly and tucked her head into her wing. The posture concerned me, but there was little I could do, so I silently wished her well and toddled on home.

UPDATE: This morning I arrived at 7:30am and spent a half hour checking the area. The two egg splats from yesterday still decorated the stairs, but no other splats had joined. The female sat out on the edge of the nesting area, looking bright eyed.

After about ten minutes, the male flew in from the southwest. He landed on the western curly-Q on the roof and started calling to the female below. She called back and then hopped off the ledge. He dove down into the nest while the female took his place on the curly-Q. He “kaaaaak-ed” and crooned from the murk of the inner nest while she watched with interest.

It occurred to me last night that another female could have come in early yesterday and killed Helen (73/D), then gone into the nest and kicked Helen’s eggs out. Perhaps the female I’d seen napping back in the murk was actually a completely different one. So, I swung my binocs up her way to see if I could get a leg band number. It didn’t take long before Helen started to preen and held her leg out – b/g 73/D. Ok. Phew.

The unbanded male, still making noise, flew out of the nest and dipped upwards. In no time, he landed atop Helen and copulation commenced. Interesting.

Afterwards, he flew off to the west and Helen went back down into the nest. By the by, she looked as healthy as ever. So, perhaps the nest just failed and the two of them are going to give it another go?

Possibilities discussed by Mary and I:

• Something damaged the eggs and Helen kicked them out to make room for new, viable eggs.
• The museum’s gang of rowdy crows got into the nest and rolled the eggs out.
• Either Helen or her mate accidentally rolled them out.
• The wind pushed the eggs out.
• The inside of the nest ledge, which we cannot see from the ground, actually slants outward and the eggs rolled out on their own.

At this point, we have few options other than wait the whole thing out – see if they will renest. As for what to do at that point, we are talking to folks and working on a plan of action. I can’t really go into specifics at this point, but wish us luck!

~ by Steph on April 8, 2008.

Posted in Chicago South Loop