Over the last week the birds have been increasingly conspicuous around St George’s, with at least one in evidence most of the time, often on the very top of the points or on one of the corners. The regularity with which they are now visiting the nest platform has led to the Twitter trigger being turned off as it was starting to generate a (very!) considerable number of activity alerts.
The birds are quite vocal now, which is another encouraging sign as the species is largely silent away from nest sites. The image above shows the male in full screech, and his call is notably higher in pitch than the female’s.
The female has been spending extended periods on the nest platform and was there for a good deal of the morning today, feeling secure enough in her surroundings to have a snooze.
Later on she undertook some rudimentary nest building, which is taking the form of moving the pea gravel around the nest platform. Often this is done by scraping, as shown is previous postings, but she also carried out some more delicate preparations, picking up and moving individual stones with her bill.
A flurry of calling at lunchtime led me to look at what was happening and both birds landed on the platform, apparently engaged in some courtship which saw them face to face with heads bowed and tails raised, a position they held motionless for several minutes.
The female then shuffled gradually towards the male, who was backed against the far wall of the box, eventually ending up almost vertical against it as he looked to keep a bit of distance between them.
After another couple of minutes, he suddenly hopped to the edge of the box and flew off. With her advances apparently having scared him off – and she was most certainly taking the lead – she settled down for another snooze and took up a pose that allowed me to see that she was half asleep, one eye open and one eye closed (see below).
According to Tim Birkhead’s excellent book Bird Sense this ability to sleep with one eye open is something birds share with aquatic mammals. It’s a way of resting one half of the brain while the other remains ‘switched on’, with the half on the other side to the closed eye taking a nap. This isn’t something recorded in all birds, however, and is known from ducks, gulls and songbirds as well as falcons. For ducks and gulls it provides an obvious benefit in watching for predators, while in species such as swifts it enables them to sleep on the wing without crashing. The benefit for falcons is less clear (to me at least!), as neither of these would seem a likely explanation, but she was definitely moving her head around while the left eye was closed, scanning the surrounding area with her right eye. Perhaps the benefit of being able to remain alert – especially at the nest site – while having a nap is all the explanation we need.
So the webcam proves its worth yet again. Several comments are showing some disappointment that the camera angle cannot be tweaked to the left to capture the perching post, which isn’t possible for reasons previously explained, but the camera continues to allow us to watch more fascinating behaviour, all to be enjoyed from wherever you are.
This time last year copulation was observed around St George’s, with the first egg laid at the end of the month. We’ve probably got 10 days or so before the first egg might be expected, if indeed they are to breed. The signs are looking very good, but let’s not count any chick(en)s just yet.