Good time to watch Woodpeckers feeding youngs - White-Backed, Middle Spotted, Syrian.
Late migrants arrive - Aquatic Warbler at the beginning of May, Marsh Warbler after half of the month. Late afternoon or evening are very good for those species. Marsh Terns numerous - start nesting and are present in many places.
Many rarities are recorded in May also due to many visitors coming:
Long-tailed Skua - May 2010
Pallid Harrier (breeding attempt in 2008)
Rarities recorded: Pectoral Sandpiper, Hawk Owl
Numerous winter visitors include Rough-legged Buzzard (common), Waxwing (common), Golden Eagle (singles, increasing).
Northern rarities possible: Snowy Owl (large marshes ans meadows), Hawk Owl.
Good period to watch wild Bisons which leave forests and wander in the fields.