Bluetit Diary    Apr 2011 (11)

Of the two females, one appears to have  blue head feathers that are more streaked than the other whose head feathers are a more uniform blue colour.  But which is this?  Whichever it is appears to be incubating.

She has a visitor.  Now is this a greeting, begging for food perhaps?  Or is she saying, "Get out of my box"?

It soon becomes clear that the visitor isn't Joe as it doesn't have food for her.  Rather the visitor is trying to sit on her ...

... and in a sort of way, succeeds!  The visitor must be the other female who wants to incubate the eggs too.

At this stage there is little interaction between the birds.  They seem to try to ignore each other.

Disappointingly, neither of these two birds appear to have streaked head feathers!

Of the two, the incumbent sitter appears to be the most hostile.

At first sight, the visitor appears much the larger bird, but this is a trick of perspective as she is significantly nearer the camera which has a pretty wide angle lens.

After a few seconds, the visitor gets fed up with the situation and leaves.

Three or four minutes later she comes back and the same thing happens - she sits on top of the incubating female.  Again, after a short while she leaves again.

Twenty minutes later there is another kerfuffle between these two females.  It starts when the incumbent leaves.

Less than a minute later, a bird enters the nest box.  But is it the same bird?

I don't think so.

It looks as though she is settling down on the eggs ...

(Now this bird has streaked head feathers.)

... but almost immediately, she gets off the nest ...

... and goes.