Ron Davis works the combination lock on the gate to the Orono Bog Boardwalk in Bangor on Sunday as bog walk director Jim Bird waits. Davis immediately set up his tripod to photograph a rarely seen bird, and Bird went out to repair a few floats that were out of place. Bird said the bog walk crew replaces five to seven hemlock boards a week during the summer. Sunday marked the opening of the floating nature trail for the 2011 season.