Numerous migratory and indigenous bird species nest in the hardwood and palm trees throughout the island, songbirds hide in bushes at Mount Alvernia and water birds inhabit swampy areas. Orange Creek in north Cat Island earned its name from the luminescent orange glow that it takes on when certain conditions are synchronized on the creek's bottom. That is the angle of the sun, the wind and waves. Nearby is Griffin Bat Cave, two inland blue holes, thought to be 60-70 feet deep with a species of shrimp and fish with no eyes living in them. One is called the Bad Blue Hole, a freshwater lake with strong undersea currents that flow through its caverns linking to the sea.