And now our eggs are about to hatch. In fact, we thought yesterday that they had already done so, as we've received feedback from a peregrine expert that our female was sitting differently on the nest. We watched the cameras all afternoon, but spotted four eggs on a changeover at 3pm. We thought the strong winds were causing the larger female to brace herself by spreading out her wings, but today she still has an outspread posture, even in calm weather. At 11am her four eggs were still visible to us.
So what are the signs to watch out for? Donna Daniel at the Columbus Peregrine Falcon Project in Ohio has just published some wonderful notes about what signs we might see. She's kindly let me reproduce them here, with a few modifications of our own.
When will they hatch?
Firstly, incubation takes about 33 days, but it's difficult to say when the birds actually start. Counting from the date of the 4th egg, which appeared on 10th April, 33 days is 13th May, so that is when we predicted hatching to occur. However, it's not an exact science, and if we count from when the 3rd egg was laid on 8th April, this gives us a hatching date of 11th May. But all along we've been saying somewhere between 8th -13th May to be safe!!
Don't be surprised if hatch begins earlier and don't panic if they are late! And, remember that the eggs won't all hatch at once - they will hatch over a couple of days.
Given that, here are some signs to help tell when hatching is close:
A day or so prior to hatching the chicks will begin vocalizing from inside the egg and pecking to work their way out. The adult birds can hear the chirping and feel the vibration, so their behavior will change. While throughout the majority of incubation they have sat tight on the eggs, they will now become very restless. They will get up and look down at the eggs more often, settle back down, and be up looking again within a short time. We have a microphone above the nest scrape, but it's not online yet. Sound will still be captured on film, and we will be monitoring it from our office inside Derby Museum.
After hatching the chicks need to be kept warm, so our female will brood the hatchlings. This may look similar to incubation but she will actually be sitting up higher and may hold her wings out from her body more than we see during incubation. Finally, keep in mind that some or all of the eggs may not even hatch. We have no plans to intervene in any way with this natural process.
Our female is now showing increasing interest in the eggs beneath her. At 5pm yesterday the male arrived carrying a small prey item, ready plucked, which suggests his instinct to bring food to the chicks was prematurely kicking in.
So let's hope for good weather, and enjoy watching the eggs hatch live on camera. And if you want a sneak preview of what's to come here, why not visit the live streaming video webcams in Ohio, where recent talk has been of a small hole appearing in one of their eggs.