Possible Nest?

[mbaldw]

Hi folks,

while I was out walking in Royden Woods (New Forest, Hampshire) last week, I came across a couple of 'balls of twigs' nestled in the branches of a couple of small trees. They looked to me as though they had been constructed, rather than just collecting randomly in the branches, and I'm wondering if they might have been some sort of nest? I didn't get too close, as I didn't want to disturb any potential occupant, hence no scale in the photo, but they were about the size of a large grapefruit. In my experience squirrel dreys are much larger and generally found higher up in the tree (this was about 6ft off the ground). I've never seen a dormouse nest in the 'flesh', but from the photos & drawings I've seen, this doesn't seem to fit.

Does anyone have any suggestions, or am I reading too much into it?

Cheers,
Marc.

[The Woodman]

I don't think what you saw is a nest at all, mbaldw. Commonly called "witches broom" these growths are fairly common on birch and are caused by a fungus called Taphrina betulina (it's probably been renamed since I learnt about it).

Fungal spores land on the young shoot and the hyphae infiltrate the barks cambium resulting in a growth of many side shoots giving the broom like effect. Altogether harmless to the tree.

Witches brooms in other tree species can be caused by insects, some mites called Eriophyes.

I dare say you will get some more information from others.

[mbaldw]

Sounds good to me - having Googled it, some of the pics I found look pretty much identical to the growths I saw. Thanks very much for the info Woodman.

Cheers,
Marc.

[fairplay]

Woodman has said it all !

For some time though there has been some doubt as to the true causer of Witches Broom on Birch.
In his book 'Plant Galls in Norfolk' Rex Hancy merely writes "mycoplasma-like-organism (?)" as a possible causer for the gall, but there seems little doubt that Taphrina betulina is present.

Neil.

[mbaldw]

Thanks for the additional info Neil, I appreciate your help.

Cheers,
Marc.

[Tracey.A]

I knew it was witches broom, but didn't really know what caused it. That's why I found the Woodsman's information about it very interesting.

Tracey