Bluetit Diary    Jan 2004 (5)

 

 

Saturday 31st January

We are trying to determine how many different birds come into each bird box.  The problem is that even at these close quarters, all bluetit look pretty much alike!

My theory is that the most variation is to be found in the head feathers, in particular in the size and shape of the white band around the back of a bluetit's head.  Here are a couple of picture to show what I mean.

The point of these two images are that they are of the same bird.  We know that because they were taken three seconds apart at about 11.30am and we also have two other images taken between these shots.  They are the same bird!  However, the white band round its head looks very different.  Why should this be?

We think that in the picture on the left, the bird is stretching forward which compresses feathers at the back of its head; whereas in the right hand picture, the bird is upright and looking straight ahead.

These two pictures were taken 3 minutes apart in the early afternoon.  The first bird left and so the second bird could be a different individual.  We think that the one on the left is the same as the one in the upper two pictures and the second bird is a different individual.

From our previous year's experiences, we would suggest that the first bird is the male.  It's head feathers are a bit darker, more of a navy blue, than that of the bird on the right and the head band is broader than the other bird's.

One more image of each bird - is it the male on the left and female on the right?  Hopefully, time will tell!

In any event, it looks as though only two different birds have entered Box1 today.