We start this sequence with a bluetit in Box2 with a feather in its beak. But which female is it?
Suddenly a second bluetit enters the box.
I think this second bird is Spikey, mainly because the other bird isn't! There is no sign of any spikes sticking out of the first birds wing feathers.
Note that they aren't immediately at each others throats.
You can clearly see a short stub, or spike, sticking out of the lower bird's left hand side.
They seem to be warily summing each other up.
The next thing that happens is that Bess (at the top) makes a move towards the nest cup.
This seems to provoke a little reaction from Spikey, but nothing violent.
Now Spikey becomes more hostile. See her open beak and her left foot on Bess's flank.
Bess's only reaction is to draw back a bit. Spikey also draws back.
Bess turns to go and Spikey moves to the nest cup.
As Bess moves to the exit hole, Spikey settles down in the nest cup.
However, directly Bess disappears, Spikey moves to the exit hole . . .
. . . and she doesn't stay guarding her nest in case Bess comes back. She, too, leaves the nest.
These two still aren't the best of friends, but they aren't total enemies either. We shall see how the relationship develops once one of them starts laying eggs!