Merced National Wildlife Refuge Is a Valley Treasure 

Like a concierge at a grand hotel or the conductor of a philharmonic orchestra, Gabriel Sandoval fine-tunes the environmental surroundings of the Merced National Wildlife Refuge (NWR). It is a complex of wetlands, ponds and grasslands and riparian woodlands in the agricultural heart of the San Joaquin Valley along the Pacific Flyway. He is the year-round manager of the refuge, and his job with the U.S. Fish and Wildlife Service is to make sure the wildlife is thriving.

“Managing marshes is both an art and a science. You plan to have different marshes that have different feed for the birds, like swamp timothy, water grass and all sorts of vegetation that certain waterfowl or certain birds prefer. Sometimes some marshes are more favorable to grow certain vegetation types over the other.”

The Merced NWR was established in 1951 under the Lea Act and Migratory Bird Conservation Act. The object was to attract wintering waterfowl from neighboring farmland where their foraging activities were causing crop damage. Changing agricultural practices and refuge management activities over several decades have resolved that problem.

Now, the refuge is a collaboration between wildlife agencies and local farmers. It is an accessible treasure trove of wildlife in the Central Valley existing alongside grain fields and dairy farms.

Operating the wildlife refuge is an intensive daily enterprise. Separate ponding areas, native grasslands and riparian habitat types must each be customized to accommodate a variety of foraging areas that are used by numerous bird and mammal species that reside here year or stop over on their migration. Vegetation management is important in maintaining habitat. It takes a lot of mechanical work and a strategy to prepare the basins to be flooded for the tens of thousands of migratory birds that inhabit the refuge in the fall and winter. Sandoval says it is a fine-tuning process.

“Managing the refuge is pretty much a year-round process. So, I’ll probably start normally right around now. This is when we put water throughout the landscape. We call it flood ups. You don’t want to really rush putting water into these units because, depending on the water depth you bring different birds that come to these units. So, the slower it is, it allows more opportunities for a lot of migrating shorebirds to come.”

The refuge gets surface water through the federal water project and a local creek, but pumping groundwater is the mainstay of the management process. Every task is timed to mesh with the seasons and lifeways of the wildlife with water levels constantly adjusted to their needs. Sandoval explains that it requires a strategy and careful planning.

“We start flooding up right around August when we still have pretty high temperatures. There are some marshes that are going to hold more water than others. I have to carefully, methodically think which ones we are going to do and how long it might take. What would be the next marsh after that? And I don’t want to do it all at once because if I do, then that’s not going to give enough time for the shorebirds to really come and be able to feed successfully.”

Once everything is flooded up, Sandoval must constantly make sure that the water is maintained at a certain level. Some of what determines the water depth is temperature and precipitation. He has to constantly monitor the deep wells to make sure they are functioning properly. Depth gauges around the ponds are regularly checked to make sure the required water level is maintained in each of them.

Sandoval aims to manage for as much diversity as possible, trying to provide a water level in some marshes that are very deep and favorable for diving ducks along with shallower wetlands for long-legged wading birds.

The most important thing to consider, Sandoval observes, is bird activity. “How is bird activity overall within the marsh? Are we seeing a variety of species in this marsh? What’s the number of each species we are seeing within each [part] of this marsh?

“If we’re seeing a lot, then clearly the birds are really favoring that specific water level. If not, then it could be the water level, it could be other external factors. It could be that they’ve found more favorable habitat elsewhere.”

At winter’s end, when warming spring temperatures emerge and migratory birds have left the refuge, Sandoval begins drawing down the water levels in the ponds to manage the plant life in the marshes. It must be accurately timed. “Shorebirds are starting to migrate. I can’t do it all at once because if I do, that’s not going to give shorebirds the opportunity to really be able to forage and feed in the area.”

There are four different tools that are used to manage the plants in the marshes. They can mechanically remove a lot of undesirable plants with weed whacking and sometimes with tractor operations. Grazing domestic animals is another tool used to control plant life. That was once accomplished by the vast herds of tule elk and pronghorn antelope that roamed the Valley feeding on grasses and shrubs while replenishing the land.

Grazing animals help the grasslands habitat by removing the thatch invasive plants that hinder the growth of native grasses. The refuge works with private ranchers who bring herds of cows and sheep to achieve the refuge’s management goals of keeping the vegetation at a certain height so that when the birds come or when the vegetation grows back it is not too messy or cumbersome.

On occasion, chemicals are used sparingly to check some of the invasive plants. Prescribed fire is another tool Sandoval and his crew use to manage fuels and enhance the ecology of the refuge.

Right now, the refuge is spectacular. More than 10,000 acres swarming with wildlife. Some 20,000 lesser sandhill cranes along with 60,000 arctic-nesting Ross’s geese, snow geese and white-fronted geese are reposing and nourishing themselves on their migratory journey.

They are joined by many other waterfowl such as mallard ducks, northern pintails, eared grebes and buffleheads. And waders such as the great blue heron and snowy egret, American avocet, white-faced ibis.

Long-billed curlew and long-billed dowitcher inhabit the shallower edges, probing and spearing prey. There are eagles and several species of hawks and raptors. The wetlands and higher elevation grasslands host dozens of species of songbirds like wrens, thrushes, warblers, and blackbirds and owls. The bird list goes on and on. There are four-footed creatures, as well, like black-tailed deer, racoons, ground squirrels and beavers. All around are a vast array of butterflies, bees and many other insect species.

A five-mile auto tour and four walking trails brings visitors up close to the treasures. Merced National Wildlife Refuge is an all-season destination, and there are resident species to see other times of the year.

Sandoval suggests it’s important to stop, look and listen, “Year-round you can see wildlife, and I think people often have that misconception that we’re almost like a zoo sometimes, that the animals are guaranteed to be here. But no, they’re wild animals. They come and go as they want.

“And you know, if you really want to see something, you’ve just got to stop, listen and just be really in tune with the environment around you.”

Whether driving around the refuge or walking along the trails, it is easy to imagine the San Joaquin Valley as it must have been in the past, especially on clear, sunny days when the Sierra and Coast Range are in view. Gazing at the wide horizon with the misty silhouette of distant trees etched into the surrounding landscape while serenaded by the squawking of geese and trilling of meadowlarks give one the feeling of being here in an ancient time.

John Muir, when viewing Central California for the first time, described it this way, “The valley of the San Joaquin is the floweriest piece of world I ever walked. One vast, level, even flower-bed, a sheet of flowers, a smooth sea, ruffled a little in the middle by the tree fringing of the river and of smaller cross-streams here and there, from the mountains.”

Sandoval considers his job as continuing in that tradition. “What I’m trying to preserve is this landscape. Unfortunately, a lot of that has been lost to human development.

“We’re a refuge for a reason. We are going to be here for many years, and I’ll do my best to try to preserve what we have now and ensure that future generations can enjoy that resource.

“For me, it’s an honor. Every time I’m out here looking at the birds and sunrise or sunset, I’m like, ‘wow, this is a gem.’” 

Merced NWR is a Valley treasure, but Sandoval says that ironically many who live in the region are unaware of it, “When I talk to visitors, I ask them where they are from and the majority of people will tell me they’re from the Bay Area, or even sometimes from places in Europe. And then when I talk to people that are local, even to the city of Merced, people are sort of mind blown that this exists.”

Merced is part of the larger San Luis National Refuge complex. Just north of Los Banos, the San Luis refuge is home to large concentrations of ducks, geese and swans, as well as herds of stately tule elk. The San Joaquin refuge farther north is the winter habitat for the Aleutian cackling goose, where it recovered from an endangered species listing. Together, they preserve a vital link in the Pacific Flyway and a refuge of biodiversity. A small part of the San Joaquin Valley as it once was.