California Ricelands and Waterbird Habitat
- Part I:
Overview of Ricelands and Waterbird Habitat - Part II:
Overview of Waterbird Ecology and Conservation
Goals/Needs - Part III:
Sacramento Valley Species Snapshot - Part IV:
Riceland Shorebirds - Part V:
Riceland Wading Birds - Part VI:
Riceland Marsh Birds - Part VII:
Riceland Waterfowl - Part VIII:
Cooperative Partnerships to Enhance Ricelands Habitats - Part IX:
Riceland Waterbirds Future Vision - Part X:
Technical References
Part I: Overview of Ricelands and Waterbird Habitat
California’s ricelands span more than 500,000 acres in the Sacramento Valley. They not only provide important livelihood for farmers and food for people, but they also provide significant habitat for a variety of waterbirds. This is because rice and waterbirds have something in common- they both need a watery home or habitat to grow and survive.
The cycle of rice provides habitat for waterbirds almost year-round. In late spring, rice fields are flooded with 5 inches of water and rice seed is dropped on the field from a low-flying plane. The water is typically drawn down allowing the rice seed to germinate. Once the seeds germinate the field is re-flooded to 5 inches. Small shoots of green rice begin to show above the surface of the water as the rice grows. In the next three to four months the rice will continue to grow, resembling tall stands of green grass.
As the rice matures it develops a seed head, called a panicle, at the top. A panicle is comprised of many seeds held closely together. A couple of weeks before harvest (in late August or early September), the fields are drained and the soil is allowed to dry so the harvesting equipment can enter the fields. The harvester, or combine, cuts the rice stalks, pulls the vegetation into the machine, and separates the seeds from the stalk. The seeds are dumped in the bin of the combine, and, when full, a specialized tractor collects the seed. The process continues until all the fields are harvested. The remaining rice stalk in the field, called stubble, is sometimes left standing and other times is chopped and/or buried into the soil. Only a small percentage (10-12 percent) is burned.
After these mechanical processes are complete, rice fields are flooded to break down the remaining rice stubble. This post-harvest flooding combined with flooding during the growing season provides habitat for many species of waterbirds. For most of rice history, fields were burned after harvest to remove the remaining straw. This practice was gradually phased down through the 1990s to improve air quality, and flooding of fields became a popular practice to help decompose the straw. A by-product of this was the creation of hundreds of thousands of acres (currently about 300,000) of flooded wildlife habitat in winter.
It’s important to consider where the rice fields are and what was there before them. The Sacramento Valley is the far northern portion of the great Central Valley of California. The Central Valley stretches 450 miles from north to south, is about 40 miles wide and encompasses 10 million acres or 10 percent of the entire state. Before the Gold Rush of the mid-1800s and the gradual transition to agriculture, the Central Valley was a mosaic of rivers, small creeks, sloughs and wetlands interspersed with majestic stands of Valley Oaks and grasslands. Waterbirds flocked by the tens of millions to more than 4 million acres of wetlands in the Central Valley, where they found a bounty of food in the water and mud.
Since the mid-1800s, as agriculture took hold, these natural habitats began to disappear as did the wildlife. Agriculture and urban development have replaced more than 95 percent of the historic wetlands and in turn reduced the population of waterbirds in the Central Valley. Fortunately, something hopeful is happening for the birds.
Today farmers, bird scientists, and birders are seeing something that is pleasantly surprising and exciting: farmers helping wildlife. Since both rice and waterbirds need a watery habitat to survive, they seem to be getting along quite well in the Sacramento Valley. During the growing season in the spring, waterbirds come in large numbers to eat the bugs in the water and in the mud. The relationship between rice and waterbirds has improved even more since the mid-1990s as farmers began to phase down post-harvest burning and replace it with post-harvest flooding. The majority of rice farmers in California are now working their straw into the soil instead of burning it, and the majority of them are also flooding their fields, providing much needed habitat for waterbirds in the winter.