The Central Valley of California, a vast, flat expanse, stretches approximately 450 miles from north to south and 40 to 60 miles wide between the Sierra Nevada and Coast Ranges. This region, covering about 11% of California’s land area, is widely recognized for its agricultural productivity, producing a large share of the nation’s fruits, vegetables, and nuts. The Central Valley also serves as a home for a diverse array of wildlife.
The Central Valley’s Diverse Habitats
The Central Valley encompasses several distinct ecosystems. Wetlands, including the Sacramento-San Joaquin Delta, represent the largest remaining wetland area in California. These areas, often managed as wildlife refuges, provide habitat for numerous species.
Historically, the valley featured extensive grasslands, marshes, and riparian forests. However, human activities have significantly altered this landscape, with over 94% of natural wetlands lost to agriculture and urban areas. Pockets of native grasslands persist, characterized by a Mediterranean climate with hot, dry summers and cool, rainy winters.
Vernal pools, unique seasonal wetlands within the grasslands, fill with water during the wet season, creating specialized habitats. Riparian zones, found along rivers and streams, also contribute to the valley’s habitat diversity, supporting a wide range of plants and animals. Agricultural lands, though altered, contribute to the habitat mosaic, particularly for species adapted to co-exist with human activity.
Mammal Residents
The Central Valley supports a variety of mammals adapted to its habitats. The San Joaquin kit fox, a small canid weighing around 5 pounds, is found in the southern San Joaquin Valley’s grasslands and desert habitats. These nocturnal foxes use dens for shelter and temperature regulation, and they commonly prey on kangaroo rats, mice, and ground squirrels.
California ground squirrels are a common sight across the valley’s grasslands and sandy areas, serving as a food source for many predators. Other rodents, such as various species of kangaroo rats and pocket mice, also inhabit the region, forming a significant portion of the diet for species like the San Joaquin kit fox. Coyotes are widespread across the foothill grasslands and agricultural areas, opportunistically hunting small mammals and scavenging.
Badgers, though less common on the valley floor, are present in surrounding foothills and rely on open spaces for digging their burrows, primarily consuming ground squirrels and other small burrowing mammals. Three species of rabbits—the desert cottontail, brush rabbit, and black-tailed jackrabbit—are also found in the Central Valley, serving as prey for many predators. Tule elk, once part of large herds, are now found in remnants of their historical range within the valley.
Bird Species
The Central Valley is a significant area for bird diversity, serving as a stopover along the Pacific Flyway, a major north-south migratory route. Millions of birds, including waterfowl, shorebirds, and songbirds, migrate through or winter in the valley annually. The Sacramento Valley alone attracts over 1.5 million ducks and 750,000 geese each winter.
Waterfowl, such as ducks, geese, and sandhill cranes, rely on the valley’s wetlands and agricultural fields, particularly flooded rice fields, for food and rest. Sandhill cranes, with their large size and six-foot wingspan, spend winter months in the valley’s marshes. Raptors like red-tailed hawks, great horned owls, and American kestrels also inhabit the valley as predators.
Songbirds, including western meadowlarks, contribute to the valley’s avian richness. Managed wetlands, including federal and state wildlife refuges, provide habitats for diverse bird populations. The valley’s agricultural landscapes also offer resources for birds, demonstrating the connection between farming practices and avian conservation.
Reptiles, Amphibians, and Fish
The Central Valley is home to a variety of reptiles, amphibians, and fish adapted to its terrestrial and aquatic environments. Reptiles include snakes such as gopher, garter, and rattlesnakes. Lizards, like the western fence lizard, are common, while the blunt-nosed leopard lizard, an endemic species, inhabits desert grassland and shrub habitats in the San Joaquin Valley.
Amphibians in the valley, such as the Pacific tree frog, are common in various habitats, including suburban gardens and ponds. The California red-legged frog, a federally threatened species, prefers slow-flowing streams and ponds, and while historically impacted by habitat loss, efforts are underway to support its populations.
The valley’s rivers and waterways support several fish species. The Sacramento splittail is an endemic fish species found in the Central Valley. Chinook salmon also complete their anadromous journeys through the valley’s river systems as they migrate from the Pacific Ocean to their spawning grounds.