Earlier this evening the thickest trunk on my birch broke at the base and fell.  Fortunately it fell onto a strong washing line and none of the dogs were outside, and the line saved my apple tree from being landed on!

It's got me a bit worried though.  It is windy today but not very - that tree is withstood MUCH stronger wind than this.  Gale force.  It's about 25ft high, and around 9 years old so not particularly old either.

I can't see anything abnormal with the bark or trunk where it snapped, all looks healthy.  Should I be worried about the other trunks (another thick one and two thin, the other thick one is also 25ish feet tall)?

ETA a photo of it after falling, if it helps any.

https://lh4.googleusercontent.com/-XYKDLX5MQ18/Ufqtpp4n6RI/AAAAAAAABaI/2kPrDlLqKhY/s912/CAM01355.jpg

There's been some trees round here suddenly falling (Cotswolds). One large branch fell just after our neighbour had just driven past it, one second later and it would have got him. A branch off a tree in Cirencester fell and hit someone. I guess it's the weird weather conditions over the last year or two that has weakened some trees. Might well be advisable to get a tree surgeon to check there is nothing fundamentally wrong with the tree

This is a natural phenomenon during a drought when trees are under heat stress; they drop branches to reduce water loss through their leaves as a survival measure. It's called 'cladoptosis'.

Where we live is fairly wooded and I think we've had several birch trees fall. The last one was quite big, it just went, no wind or anything but it seemed rotten at the base and for about an hour after water was spurting up out of the base like a fountain!

You are a font of knowledge JG, I didn't know that, what a great survival trick, think we should all get some water on our large trees particularly our birches pronto then, hopefully it will stop this happening.

> when trees are under heat stress

They are also at greatest risk of falling when covered in leaves.

More information. My son's a tree surgeon so I've picked up quite a lot of stuff from him!