Last year’s juvenile, now changing into an adult, continues to hold territory on the Power Station daily with the Falcon and the adult Tiercel remains half a mile away to the east.
The 2 Tiercels clash daily but the adult Tiercel is unable to move the sub adult Tiercel on, the Falcon daily goes and sits with the adult Tiercel to the east as they are a bonded pair, albeit the adult Tiercel cannot hold to the Power Station site and spends his time away from it.
It really is a strange scenario and something I have not come across before, for breeding stability the sub adult needs to go, it’s quite obvious now after all these months the adult Tiercel is not going to give up.
At one time the adult Tiercel did slip by the sub adult and displayed to the Falcon, I naturally thought that’s it, he has displaced the sub adult but unfortunately that was short lived and normal service was resumed later that day.
|New adult Tiercel displaying on left - last years infertile egg still present|
|Sub adult - blue tones coming through|
Neither Tiercel will give up it seems, what tragically happened this year with the sub adult spiking the 3 chicks, not his own chicks, was obviously down to clumsiness but the stress of the situation could well have been a contributing factor.
It’s easy to read human emotions into it, they weren’t his own chicks but the adult Tiercels, would he have been more careful and attentive around them, if they were his and he had a stronger bond to them?
You might have seen recently that another pair that I monitor has laid exceptionally late with a clutch of 3 fresh dark coloured eggs observed on June 20th – 27th.
This is a pair that I monitor at least twice a month and I had given up on them breeding this year, there was no signs of breeding in the normal months of March, April and May so naturally thought that they would just summer and hold to territory.
They bred successfully in 2018 and I had been checking the nest ledge regularly as above, however towards the 3rd week in June I observed a nest relief with the Tiercel letting her feed while he disappeared onto the ledge.
Further watching eventually showed 3 eggs amazingly, 3 months behind normal London laying.
As you do, I always look for reasons why.
Failed elsewhere – no - nest ledge has been used since 2017 and monitoring them has only showed normal activity before this with birds present and territorial.
New adult or adults – no both the same birds, the Falcon is ringed and the Tiercel has distinctive head marks so I know it’s him.
It’s a strange one and if successful, they will be hopefully be fledging young in September, crazy!