Early birds can check out the flora and fauna of the Hudson River Park in guided nature walks every Sunday morning at 9 a.m. through August 26. The free walks offered by the Hudson River Park Trust begin at Pier 40 on Houston Street just west of the West Side Highway at 9 a.m. and last about an hour. Participants should plan to walk about two miles and are asked to leave their dogs at home so as to not scare away wildlife.