Flood Irrigation and Migrating Waterfowl

It’s American Wetlands Month. Last year around this time, I wrote a brief post describing the importance of wetlands and why they are a conservation concern. This year I thought I would write a little about an issue surrounding wetlands that has recently come to my attention: flood irrigated agricultural land and its benefit to migrating waterfowl.

The term “waterfowl” refers to birds that live on or around freshwater, such as ducks, geese, and swans. Like many other birds, they are migratory, typically flying north in the spring to breed and spend the summer raising their young, and then flying back south in the fall to overwinter. There are four major flyways (or migratory flight paths) in the United States: Pacific, Mississippi, Central, and Atlantic. Along these flyways, migrating birds need places to rest and feed in order to maintain the strength to make it to their seasonal homes. As wetlands have disappeared across the country (and the world), essential areas of respite have become few and far between, threatening the survival of this important group of birds.

Dunlins - Calidris alpina (photo credit: www.eol.org)

Dunlins – Calidris alpina (photo credit: www.eol.org)

Historically, wetlands have largely been diminished and degraded due to human settlement on the floodplains of major rivers. Floodplains are examples of temporary or seasonal wetlands, flooded in the spring when snow in the mountains is melting and during periods of heavy rains but otherwise dry throughout most of the year. These areas appealed to early settlers because they were flat, had great soil for agriculture, and were near a water source. The only downside was the flooding, so levees and dams were built, diversions were made, and eventually these great rivers were tamed, virtually eliminating their status as seasonal wetlands and the important ecological functions that go along with that.

This has spelled disaster for migrating waterfowl who rely on floodplains to be flooded in the spring, providing them with staging habitat on their journey north. Biologists have recognized this issue and have made efforts to protect and restore wetlands in order to provide this essential habitat. But restoring wetlands is a major feat. Rivers that supply both temporary and permanent wetlands aren’t what they used to be. There are myriad diversions and modifications, and with a continually growing human population, too many uses for the water. So that’s where farmers and ranchers come in.

In the spring, many farmers and ranchers flood their fields in order to irrigate crops. Migrating waterfowl take advantage of these flooded fields, stopping to rest and feed. Recognizing the role that flood irrigation has on the survival of these birds, biologists are working with farmers and ranchers along flyways to ensure that their land will remain in agriculture and that land owners will continue to flood irrigate (rather than switching to overhead irrigation). In California for example, rice farmers are being paid by the Nature Conservancy to flood their fields in conjunction with spring and fall migrations in order to ensure that birds will have staging habitat along the way. So, despite humans playing a major role in reducing habitat that migrating waterfowl require for survival, we are finding ways to make up for it. This is just one example of how we can help protect and improve biodiversity in our human-dominated landscapes.

Read more about protecting migrating waterfowl in the Pacific Flyway here.

Geese in a Flooded Rice Field in California (photo credit: NRCS)

Geese in a Flooded Rice Field in California (photo credit: NRCS)

Celebrate American Wetlands Month by learning more about them. Here are some links to get you started:

U.S. Environmental Protection Agency

Association of State Wetland Managers

Defenders of Wildlife

 

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2 thoughts on “Flood Irrigation and Migrating Waterfowl

    • Thanks! Yes, the best part is the collaboration between private land owners and concerned environmental groups – finding ways to work together to solve important problems. It’s encouraging.

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