Wildlife in the Delta

The California Delta, also known as the Sacramento-San Joaquin River Delta, includes roughly 1,000 miles of waterways that form a triangle spanning from Sacramento to Stockton to Pittsburg. More than 750 species of animals and plants live here, some only found in the Delta and nowhere else in the world.

Some of the mammals found in the California Delta include the beaver, river otter, muskrat and shrew. These mammals generally live in riparian habitats, where they build dens and burrows and hunt or forage for food. Delta mammals typically feed on vegetation such as aquatic and woody plants, other mammals such as rodents and rabbits and invertebrates such as crayfish and insects. Mammals such as the river otter also live and hunt in wetlands along the Delta and travel long distances up rivers and streams in search of suitable habitats.
Most of the species of fish in the California Delta are found in slower waters, such as those in the northern area of the Delta. Some types of fish found in Delta waters include salmon, catfish, cod, sunfish and shad. Species such as the green sturgeon are both freshwater and saltwater fish, living in the ocean as adults and swimming to freshwater rivers and streams to reproduce. This species' population is of concern mainly due to reduced resources and spawning areas. California Delta fish typically eat smaller fish, insect larvae, shrimp, plankton and clams.
Various species of water birds, including ducks, geese, swans, pelicans and herons live in and travel to the California Delta. Birds such as the California brown pelican are permanent residents of beaches and islands along the waterways of the Delta. Although the brown pelican's population is threatened, places like the Nature Conservancy have restored habitats for established and migrating birds. The diet of these Delta birds includes vegetation such as crops of corn, fish, rodents, crustaceans and reptiles.