dancing juv Marsh Harrier

when Marsh Harrier juvs are newly fledged and exploring areas around the nest I have often seen them try to land on things and then suddenly jump in the air when their feet touch the object; I assume that the insides of the toes are very sensitive, ready for closing on prey when they touch it in a hunt?, and they have yet to ascertain what the reaction means -- they will often land on grass and come up clutching a clump of earth or grass only to drop it quickly; they also run around on open ground chasing insects -- seems to be a wide variation in fledging dates again this year with several young strong on the wing taking prey form adults in flight while a number of broods are still in the nest.