After the appearance of the first egg on Thursday, yesterday was full of anticipation, but the second egg failed to arrive. The female spent extended periods on the nest, adopting postures that suggested she might be about to lay (as below), but it wasn’t to be.
Both the tiercel (male) and the female incubated over the course of the day, mostly in rather half-hearted fashion, often standing over the egg rather than snuggling down onto it.
When I checked the webcam early this morning I fully expected a second egg to be visible, but there was still just the one. Could there have been a complication? I’d planned to go down to St George’s in any case, and when I got there both adults were around the nest platform, all looking fine. By the time I got home at 11 after running some errands a second egg had appeared, at least 48 hours (probably some 54 hours) after the first.
Another visit to St George’s in the afternoon revealed some surprises that would be impossible to appreciate via the webcam. On arrival the male was on the ledge to the E (the platform is on the N-facing ledge) and I assumed the female was on the eggs. After a few minutes, however, a Peregrine came into view from the E, fairly high up and carried on towards the N. I presumed this was the female on a hunting trip, but a little later the resident female popped up out of the nest platform – clearly a third Peregrine is in town. She hopped onto the perch and became very agitated, calling repeatedly.
Whatever was causing the agitation wasn’t going away and she set off towards the city centre, where another Peregrine could be seen circling – apparently a fourth! Having defended the territory she returned and landed on the ledge, from where she called to the male, who had not moved during the whole episode. He flew round and they mated, which was interesting to see as the eggs are well on their way. In his seminal study of the Peregrine, Derek Ratcliffe states that ‘copulation continues in most pairs until the third egg is laid, and occasionally occurs after the clutch is complete.’ Whether this is a biological necessity at this stage or ongoing pair bonding isn’t clear to me (or to Radcliffe), but it seems that it could well be both, with the latter the more likely option.
The female eventually returned to the nest and the male took to the air, giving a good fly-past, even allowing the ring to be seen.
During the afternoon the weather in Sheffield took a turn for the worse, with a drop in temperature and steady rain turning to sleet. The pair seemed to respond to the conditions, and took to incubating the eggs, the male also doing a stint, as below.
So no complications after all and things progressing nicely. Apparently the typical interval between eggs is around 48 hours, with 52-62 hours in captive Peregrines, so another egg may come tomorrow or may not: watch this space and the webcam to find out!