The majority of the original vegetation on the island has been replaced by shrubs and grasses. The vegetation is a miniature mosaic of matorral, barren rock, various size trees, and shrubs mixed with ferns and perennial herbs. Nearly all of Santa Clara is abundant in the introduced "Rubus ulmifolius", "Aristotelia chilensis", "Ugni molinae", "Lantana camara" and "Lonicera japonica". Some have the potential to be serious pests, having fleshy fruits that are bird dispersed, in addition to weeds such as "Danthonia collina", "Stipa laevissima" and "Piptochaetium bicolor". There are no permanent sources of fresh water on the island. Vertebrates inhabiting the islet include birds, some endangered, which make their nests on or visit the island. The island (along with neighbouring Robinson Crusoe Island) has been recognised as an Important Bird Area (IBA) by BirdLife International.