The Mistle thrush is the UK’s largest thrush and in early autumn birds gather in large flocks to feed together. But as soon as holly berries appear, they will split off on their own or into pairs and get defensive. Each bird or pair will find itself a holly tree or bush teeming with berries and will set up a territory.
The berries on that tree won’t be eaten, but will be guarded with such care that no other birds can take them either. Mistle thrushes are so good at protecting their trees, just in case, that by spring many will still have their full crop of berries untouched, long after any unprotected holly has had its fruit stripped.
So, if you see a holly tree that’s still full of berries at Christmas, you’ll probably find there’s a Mistle thrush nearby keeping out a watchful eye for thieves.
This is a possibility for your holly trees Eric.
Birds see many more colours than humans can. They have additional colour cones in their retina that are sensitive to ultraviolet range so they see colours that are invisible to humans. That's why red berries are usually the first to be eaten, being the brightest and more attractive, as opposed to the drabber orange ones which are the last to go. Another explanation for your Blackbirds leaving your orange berries to last George.
When your trees are full of berries and therefore more food to choose from, our wonderful birds can afford to be 'picky' - just like humans really
Laurie.
