Grasslands Ecological Area: A Wetland of International Importance

Last February, I wrote a bit about the plight of wetlands worldwide, their many values, and what is being done to protect and restore them.  

Today, as spring begins to unfold across the Great Central Valley, I'd like to introduce you to a Ramsar Wetland of International Importance, right here in Central California: Grasslands Ecological Area.

But Grasslands Ecological Area is not just any wetland of international importance: This is my home wetland!  And don't you think we should all have our own home wetland, a quiet patch of marsh to visit, take pride in, connect with, and protect?

My relationship with Grasslands Ecological Area started some twenty years ago, when my parents began taking me out to the San Luis National Wildlife Refuge on weekends to wander and roam, exploring the trails through wetlands and grasslands in search of wildlife.  (There's a great photo of my eleven-year-old overall-clad self, sitting in the mud at marsh's edge, grinning and pointing to a well-defined set of beaver tracks.  A mammal tracking book is open on my lap, and in my left hand I'm holding a notebook where I have carefully sketched the tracks in question.  This is what I mean by calling a place my "home wetland.")

The aforementioned photo of my young self, happily immersed in nature in the wilds of the San Luis National Wildlife Refuge.
(Aside: braces and contact lenses are quite possibly two of the greatest things that have ever happened to me!)

Grasslands Ecological Area (GEA) covers 160,000 acres of the northern San Joaquin Valley in Merced County, forming a block of habitat roughly 30 miles long and 25 miles wide within the historic floodplain of the San Joaquin River.  

Amazingly, Grasslands Ecological Area represents the largest remaining contiguous block of freshwater wetlands in California.  

Sixty-five percent of GEA is covered by wetlands, both managed and natural, including seasonal and permanent or semi-permanent marshes, sloughs, riparian corridors, floodplains and vernal pools, while the remainder of the area is largely upland grassland.  One of the largest remaining areas of unplowed land on the floor of the Central Valley, GEA is home to the best example of Valley Sacaton Grassland left in California. 

Flood control measures and irrigation schemes have completely altered the natural hydrology of the Central Valley, and the wetlands are now largely managed by a complex series of canals and water control infrastructure.  The Central Valley Project Improvement Act of 1992 requires that a minimum flow of water be maintained to the area in order to create wildlife habitat.  Water is allocated in a way that mimics the natural flood patterns that the Valley historically experienced, creating periods of high water levels during the winter and spring seasons when the Valley experiences rain and an influx of water from snowmelt upstream in the Sierra.  During the dry months of summer and fall, water levels are allowed to fall, as they would have done historically, leaving behind a few shallow pools and large areas of mudflats.

 

While quite a bit of the land within GEA is managed as National Wildlife Refuges by the U.S. Fish and Wildlife Service, much of the land is privately owned and operated under conservation easements.  One California State Park, Great Valley Grasslands State Park, a handful of private duck clubs, and several State Wildlife Areas are also within the area.  Click here to explore a detailed map of the Grasslands Ecological Area.

California's Central Valley once boasted over four million acres of wetlands, 95% of which has been lost, mostly to draining and conversion to agriculture.  90% of California's vernal pools have been lost to agriculture and development, and 98% of the state's riparian forest habitat has been destroyed as well.  The Grasslands Ecological Area protects remaining patches of all of these critically endangered habitats, including riparian areas along 18 miles of the San Joaquin River and an additional 37 miles of riparian habitat along the river's smaller tributaries and sloughs.  

The San Joaquin River is used by fall- and late-fall-run Chinook salmon (Oncorhynchus tshawytscha), a Species of Concern under the federal Endangered Species Act.  The river's sloughs and tributaries provide habitat for the threatened giant garter snake (Thamnophis gigas), a harmless, non-venomous species of colubrid that can reach five feet or more in length.  Endangered fairy shrimp (Branchinecta sp) are found in the vernal pools of Grasslands Ecological Area, along with the threatened California Tiger Salamander (Ambystoma californiense).   

But let's talk about the birds!

Grasslands Ecological Area provides critical overwintering habitat along the Pacific Flyway for more than one million birds, including more than 10,000 Sandhill Cranes and 1,000 American White Pelicans.  Over one tenth of the entire North American populations of Gadwall, Northern Shoveler, Northern Pintail, Green-winged Teal and Canvasbacks overwinter in the Grasslands Ecological Area, with nearly 20 species of duck represented within the area during the winter.  

Tens of thousands of shorebirds, along with raptors and songbirds, stop over during spring and fall migration, while hundreds of cormorants, herons, and egrets use the area as their breeding ground.  Up to 10,000 Tricolored Blackbirds and dozens of pairs of Swainson's Hawks, both of which are listed as State Threatened, regularly breed within the area as well.  In the winter, thousands of Long-billed Curlew forage across the area's fields and pastures, and an estimated 10,000 White-faced Ibis spend the nonbreeding season in GEA.  This gathering of ibis represents the second-largest concentration of these birds in California outside of the Imperial Valley.

It will come as no surprise, then, that Grasslands Ecological Area is considered by Audubon to be an Important Bird Area, as well as a Western Hemisphere Shorebird Reserve site.

To visit Grasslands Ecological Area (and maybe even adopt it as your own home wetland!) start by taking a drive out to the San Luis National Wildlife Refuge, north of Los Banos, to visit the excellent visitor center there.  After taking in the informative exhibits at the visitor center, venture out on a range of walking trails and auto tours, into the heart of the wetlands.  Also consider a visit to nearby Merced National Wildlife Refuge, or head out into the grasslands at Great Valley Grasslands State Park.  

Check out this post for a run-down on the walking trails within GEA.