Birds will have begun nesting in earnest from the end of March and major works, to hedges in particular, would not be countenanced by a reputable tree surgeon until the nesting season is largely over. However, work on your trees, including pruning, can be carried out once a careful inspection has been undertaken of the work to be done and the proximity of nesting birds within the tree/s has been assessed. A professional, qualified tree surgeon will be fully acquainted with the need to work sensitively at this time of year and will advise on what work can be carried out now and what may need to be delayed for a couple of months or so until the birds have done what they need to do. Contrary to popular belief there is no reason why pruning etc can't be carried out when a tree is in leaf, provided it is done carefully and professionally.
Timing of tree and hedge cutting