Ivy growing up trees is often a sign that the tree isn't growing strongly. This means that the leaf canopy is not as dense as it should be and the ivy gets extra light and grows strongly. Could there be another problem such as long grass around the trunk or bad drainage etc?

What did you cut the ivy with? If you used a strimmer, did you damage the bark on the tree?

as volunteer is saying it could well be a weakness with the tree that the ivy is exployting but it just looks like cutting the ivy has done this .

Thank you for your comments. I have 3 birch trees all in a row that are in front of a 6 ft garden wall and 1 had become heavily over grown with the ivy so I thought the ivy would eventually starve and kill the tree so I cut the main ivy stems with a small hacksaw to loosen it and then pulled all the excess away. There is no grass only soil around the trees.
I will check to make sure I haven't accidently damaged the bark. If there is any bark damage will the tree recover?

thanks again for your help.

If there is minor bark damage in a single area, that should be okay - if its extensive, and particularly if it's all the way round the tree, that could cause the tree to die.
More importantly though, if you have left all the ivy roots in the soil, and they are extensive, they will certainly be stealing nutrients and moisture from the tree. I'd be inclined to deal with the ivy roots properly if the tree hasn't extensive damage to the bark.
On the subject of ivy climbing up plants and trees, my father told me it tended to target already sick or weak trees - this has absolutely not been my experience in the 25 years I've been a professional - ivy will climb up anything it can,and cling like barnacles to a boat, regardless of the health of its host.

your welcome fkr 1