The Santa Monica Mountains are in the California chaparral and woodlands ecoregion and are covered by hundreds of local plant species, some of which are very rare, and others of which have become popular ornamentals. The range is host to an immense variety of wildlife, from mountain lions to the endangered steelhead. The mountain lion population within the Santa Monica Mountains (which includes the Simi Hills & Santa Susana Pass) is severely depleted with only seven known living adult individuals. The primary cause of the decline is due to a combination of traffic related mortality (three from the area were killed within a matter of months), anti-coagulants ingested from human-poisoned prey (two individuals within the Simi Hills) and attacks by other, more dominant mountain lions (an elder male, known as P1, killed both his son and his mate. This is thought to be due to a lack of space available.) Snakes are common but only occasionally seen – the Southern Pacific Rattlesnake (the only venomous species), Mountain Kingsnake, California Kingsnake, Gopher snake, and Garter snake.