Sand dunes and ridges are the fourth zone, formed when beach sand transported by wind and waves becomes trapped by vegetation. Dunes grow and are stabilized by grasses, followed by other types of vegetation. This provides habitat for amphibians, birds, mammals, and reptiles. Old dunes can become more permanent ridges, which shelter ponds. These dunes, ridges, and ponds are often remnants of previous shorelines; at the Presque Isle State Park "Long Pond" just east of the marina, dunes and ridges mark the eastern shoreline from 1862. The fifth ecological zone consists of old ponds and marshes. Ponds protected by dunes and ridges are more stable; these old ponds support more plant and animal life, and as they fill with vegetation, they become marshes. Old ponds and marshes have high biodiversity. Nearly 400 species of terrestrial vertebrates live on Presque Isle, including 318 different birds, 48 kinds of mammals, 13 types of amphibians, and 19 reptile species.