By yesterday evening there was no sign of any breakthrough moment, with 4 eggs clearly still in the nest. However, the behaviour of the adults suggested that something was afoot, as both birds held themselves a little off the eggs using their wings as props, as in the image below.
Presumably they’ll have been doing this as they will have been able to hear the chicks in the egg and by early this morning the first chick had hatched, though we don’t know exactly when. However, by 06:20 a changeover revealed a chick. Below is a video capture from that time, provided by Ian Knowles at the University.
In the cold conditions here in Sheffield (there was a heavy frost and sub-zero temperatures on the night of 27th and snow on the windows this morning!), the adults have been sitting tight throughout the day, allowing only glimpses of any activity on the nest. On a changeover this morning A. Bateman managed a great screengrab, copied below, showing one chick and also a distinct hole in the egg nearest the camera, evident as a pale spot.
Interestingly, the male has been very active in bringing food to the nest and in incubating. As well as bringing in what looked like the remains of a Feral Pigeon early this morning, as on the weblink, he brought in another feed while I was having my lunch, though the female refused to budge and he took it away again without the chick having fed; perhaps warmth was the priority.
This evening, the female took over duties from the male at around 7 p.m. and seemed set for the night, though there was just the one chick still and the hole in the second egg looked no larger than it had this morning. I’d expect at least one more chick to emerge tomorrow, as the eggs in a Peregrine clutch hatch quite close together.
My estimate of Monday proved to be a few hours early, but today’s first hatching provides us with a perfect symmetry with last year, when the fourth egg was laid on 27th March (as this year) and the first chick also hatched on 28th April. So an incubation period of 32 days in both instances, as well as in 2013, although they were a week later then, with the first egg hatching on 5th May.
Plenty of action and excitement should follow over the next few days: hopefully by the end of the week we’ll have four healthy chicks but no doubt there will be some nervous moments between now and then.