Here's a plan for a box that would suit Jackdaws: http://www.rspb.org.uk/Images/Largeopenfrontnestbox_tcm9-226496.jpg
If you would rather buy a pre-made one, here's an option: http://www.birdfood.co.uk/ctrl/product:527;/tawny_owl_stock_dove_and_jackdaw_nest_box. In general, boxes marketed for Kestrels and Barn Owls would be suitable for Jackdaws. Put the box/es at least 5 metres up, on a wall should be OK (not south-facing though), at least 2 metres apart if you put up more than one.
My blog: http://mazzaswildside.blogspot.co.uk/
My Flickr page: https://www.flickr.com/photos/124028194@N04/
That's great, thanks!
Have a look on eBay ... Just saw one for £17 ono!
2013 photos & vids here
eff37 on Flickr
Wow Ok, will do!
Hi, I know this is years ago, but I have the same problem with jackdaws now. Did you find a nest box that worked for the jackdaws? Would be so grateful for advice as very sorry to have to evict them after years and 3 or 4 generations of their nesting in our roof.