An e-mail from Phil Riley in the University’s Estates Dept on Wednesday afternoon gave details of some electrical work required at St George’s, to start the following morning. Needless to say, this raised concern as to potential disturbance of the sitting adults with the risk of the eggs becoming damaged if the adult was spooked from the nest or getting cold if disturbance was ongoing. By very happy coincidence, the SBSG monthly indoor meeting was to take place that Wednesday evening and the speaker was to be Mark Thomas, the RSPB Senior Investigations Officer, a national specialist on raptors and the law. I had a good chat with Mark about the situation at St George’s and went down myself the following morning to see if we could find the best way forward.
After a good deal of discussion with the project manager and others we agreed that most of the work (replacing lights around the lower elevation of the church) would be able to go ahead without disturbance to the bird sitting in the nest platform. However, work on the N elevation, under the platform, was to be postponed until a later date, a very good outcome that allows a key part of the work to go ahead immediately while respecting the protection that Peregrines enjoy as Schedule 1 species.
The work involves a cherry picker to reach the light fittings and with work under way on the light furthest from the platform, the female took up station on the corner of the tower (circled in red above) overlooking the contractors, who were in clear sight of her while the male incubated. To my surprise – and relief – she did not seem bothered by their presence and continued to sit there for quite a while. As can be seen, there is a considerable amount of equipment in the area, and they seem to have become accustomed to such things, which were in place well before the start of this year’s breeding season. And when the crane swings round, it can look as if it has almost passed over the nest!
So, scare over, the birds have continued to incubate as normal yesterday and today, with turns of around a couple of hours and some great views when takeovers happen.
In the photo above, taken as the female came off after an extensive stint on the eggs, it looks as if the sternum is visible just where the barring on the chest begins, with indented patches of feathers to either side suggesting the brood patches where the eggs had been nestled. Peregrines have two brood patches, through which body heat can be transferred from the adult to the eggs, or vice versa if necessary. Watching the birds settle onto the eggs on various occasions, they always seem to settle N-S or E-W with two eggs on either side of the sternum. Might this explain why a clutch size of 4 is pretty standard for Peregrines – an optimal size of clutch to be able to incubate two eggs at each brood patch and maximise success? Looking at the male when he moves onto the clutch, it would certainly be hard to imagine him adequately covering 5 or even 6 eggs.
Again, in the overhead shot here you can see the disturbed feathers in the same area, or am I imagining it?!
A quick visit this morning confirmed all was well, with work on the lighting continuing at the E end of the church, out of sight of the platform and regular perching spots. With no Peregrines on view, a Woodpigeon flew onto the stonework half way up the church and then flew up to the ledge where the platform is, where it started to walk towards the nest!
When it got to within about 20 centimetres of the nest I was expecting some excitement! It looked for a while as if it was going to hop up onto the box, but in the end decided against it. It’s a bit of a puzzle what the Pigeon was doing, but it seemed very curious about the platform. I’ve posted before about Peregrines apparently not predating birds breeding in the vicinity of their nest, but this Pigeon seemed intent on testing that to the limit, and survived the experiment.
So an apparently routine few days became ‘interesting’, but thankfully all seems to be proceeding securely, with the halfway point in incubation just about here.