Rain Forest Adventure for Mac

From Unique 3D Screensavers:

Watch as jungle birds, big cats, primates and butterflies fly, climb, stalk and flit among gently swaying jungle folliage. A lively waterfall backdrop adds to the tropical ambiance. Set the time of day to nightime, and a dark shadowy blue hue is cast on birds, trees, leaves, butterflies and other rainforest creatures. You can customize brightness, tint, and time of day settings.

View larger image