I’m afraid our concerns for the smallest of the kestrel chicks proved correct and we unfortunately witnessed siblicide first hand. This is when older birds will eat their younger and weaker siblings when there is not enough food being supplied by the parents. It is very common among birds of prey and almost always as a result of environmental conditions. Although it can seem to us quite brutal, it is a sensible survival strategy and ensures that the strongest and fittest survive, rather than a whole brood struggling to reach peak condition and fledge. Other birds that practice this behaviour include owls, herons and egrets.
Currently there are three chicks left and you may be wondering what happened to the fourth. The truth is we are unsure whether it was the eldest and it has already fledged or if it was a second victim of siblicide. We suspect the latter is more likely as we have not had any sightings of a juvenile around the nest area, where it would still be fed by the adults until it had learnt to catch prey for itself. However, the three remaining chicks are more like teenagers now and showing all the markings of young kestrels. A week ago they were getting curious of the outside world and took to peaking over the front of the box.
Now they are getting quite restless and have taken to sitting in the entrance bold as brass. It won’t be long before they leave the nest now.
The stock dove eggs have both hatched and the parents have been feeding the chicks, also known as squabs. Initially they will have been fed a special ‘crop milk’ produced in the parents’ crop, which is a muscular pouch near the throat to temporarily store food. After about four days they are fed a mix of partially digested feed, typically seed, mixed with crop milk and after a further week just regurgitated feed.
You can just see one of the chicks under mum!