The Whittier Narrows Nature Center and Wildlife Sanctuary has 419 acres of wilderness, featuring trails that weave through dense, dry brush alongside the San Gabriel River. With 300 species of birds, bird watching is a favorite pastime. Mountain lions and bobcats have also been seen roaming, and deep inside the sanctuary, the solitude of the desert can be a liberating experience. With all the paw prints pressed into the sand around you, you have the feeling of never quite being alone. Nearby, the Nature Center Museum has collections of archaeology, botany, history, birds, bugs and reptiles. It occasionally hosts free lectures and hayrides. Unfortunately, part of the area is marred by transmission towers and power lines, and signs advertising Mobil and Shell Oil are visible on the horizon. Even so, this is a quiet, relaxing place, completely free of charge. That much, at least, is the way nature’s supposed to be. 1000 N. Durfee Ave., El Monte. (626) 575-2253.