We were hoping that things would get back to normal in Manton Bay today, but sadly it hasn’t happened. Apart from one possible sighting early this morning, 28(10) has been absent all day. It would seem that 33(11)’s unrelenting aggression on both Thursday and yesterday means 28 is extremely reluctant to return.
We have now had a chance to look back through the monitoring notes kept by project volunteers in Waderscrape hide and it makes for worrying reading. The eggs were uncovered for more than 90 minutes on Thursday and for over two-and-a-half hours yesterday. When you consider that under normal circumstances incubating Ospreys rarely leave their eggs exposed to the elements for more than a few minutes each day, this is a significant period of time. Sadly it will almost certainly result in the eggs failing to hatch.
Ironically, today has been much quieter than Thursday and Friday. Maya has left the eggs uncovered for a total of 45 minutes in order to see-off 33, but otherwise she has sat resolutely on the nest. However, having not fed since Thursday morning, she must be getting very hungry. If 28 fails to return then she will have no choice but to leave the eggs in order to go fishing. A few people have asked whether we could intervene by putting a fish close to the nest, but this is unlikely to help. Without a male to share incubation duties with, Maya would still have to leave the eggs uncovered in order to eat the fish. As hard as it is to watch, there is very little we can do to help.
With 28 clearly no match for 33, the most likely scenario now is that 33 will usurp the older male at the nest. How quickly this will happen is difficult to say. Incubating females have a very strong bond to both their mate and eggs, but if 28 continues to remain absent, then 33 may eventually be accepted by Maya. That said, 33 won’t incubate the existing eggs, and although females do occasionally lay further eggs if their first clutch is lost early in the season, we don’t think that this will happen in this case. It is far more likely that 33 and Maya will form a pair-bond and then return to breed together next spring. They should, however, remain in Manton Bay for the remainder of the summer.
Although 33 has been incredibly aggressive, we have been surprised at how easily 28 has been kept away from the bay. As Dave Cole’s latest film shows, prior to the arrival of 33, the two birds were very settled at the nest.
It is likely that 28’s damaged right wing hasn’t helped him. 33 seems much more powerful in the air, and that may be due to the injury that 28 sustained sometime between leaving Rutland Water as a juvenile in 2010 and returning as a sub-adult two years later.
We have no previous experience of seeing a breeding male driven away from his own nest; and so there is no way of knowing exactly what will happen. It could be that 28 will mount a fight-back, but at the moment that doesn’t seem likely. All we can say is that we’ll keep you up to date over the coming days.