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Delta Farmlands

Delta Farmlands Program

Beginning winter 2021, the Migratory Bird Conservation Partnership (The Nature Conservancy, Audubon California, and Point Blue Conservation Science) is partnering with the Delta Conservancy to bring BirdReturns to California’s Sacramento-San Joaquin River Delta. The Delta is an important place for wetland birds not just because of its wetlands but also because of its many wildlife-friendly crops like corn, wheat, and rice, as well as abundant surface water and location, which make it important in all years and especially important during drought when there is far less opportunity to provide additional flooded habitat in other parts of the Central Valley.


The BirdReturns-Delta Farmlands Program will provide incentive payments for farmers to flood and hold shallow water on their farm fields at certain times of year when crops are not being grown. Because the targeted birds require specific conditions, farmers selected for the program are asked to flood their fields at shallow water depths, with little to no vegetation and crop residue and minimal tillage of grain crops to ensure waste grain is available for birds.

To apply for the program, farmers can submit a bid through October 28, 2021 at 9:00 p.m. specifying the acres and duration they are willing to flood, along with the dollar amount per acre that they need to cover their costs for the program. Successful bids are those that can cost-efficiently flood up early in the program timeline, hold for longer periods, maintain shallow water depths, and draw down water slowly in the late winter and spring.

Bid Ranking and Scoring Process

All bids will be ranked and scored by the Migratory Bird Conservation Partnership and the Delta Conservancy. Representatives from these groups will assess bids according to standardized methods, using the best available science and tools that predict the habitat value of each bid according to its location in the landscape and history of bird use in the surrounding area. Ranking criteria include an analysis of potential bird abundance, historic habitat availability, acres of flooding, duration of flooding, proximity to existing wildlife areas, and bid cost.

Winter 2021-2022 Program

In response to the severe drought in 2021, the Migratory Bird Conservation Partnership, with funding and support from the California Department of Fish and Wildlife, is implementing an emergency drought response program to increase the amount of habitat during winter. This program will also allow farmers to extend flooding into spring, a time of year when migratory birds often need more habitat.

Program Details
  • Program bids due by 9:00 p.m. on October 28, 2021
  • Contracts: Short-term commitment of three weeks to five months
  • Timeline: December 1, 2021 through April 30, 2022, with flood-up required in December and preference given to those who flood for longer periods
  • 30-acre minimum field enrollment
  • Flooding: Flood and maintain depths between 2-4 inches throughout flooding period
    • In sloping fields, the shallow end should be maintained at approximately 2 inches; the deep end may be greater than 4”; however, if possible, cross-field berms should be installed to maximize shallow depths
    • Fields that are uniformly deeper that 4” are not acceptable
  • Post-harvest stubble management required; a combination of any of the following post-harvest crop stubble treatments and incorporation practices may be used to meet our field condition requirements: burn, chop, roll, bale, single pass disc, single pass chisel, or stomp (see below for examples of suitable and unsuitable conditions)
  • Gradual drawdown required: After the required flooding duration ends, water levels should be reduced incrementally over 2 weeks

Required Field Conditions

Suitable Conditions: Ideal shorebird habitat with mudflat-like conditions
© Tim Poole
Unsuitable Conditions: Poor field conditions for shorebirds with too much standing crop stubble and water that is too deep
Suitable Conditions: Great shallow flooded habitat, attracting lots of birds
Unsuitable Conditions: Poor field conditions for shorebirds with too much standing stubble and water that is too deep
Suitable Conditions: Good field conditions, though smaller clumps are better
Unsuitable Conditions: Poor field conditions with too much undecomposed vegetation; thick, matted vegetation makes it difficult for birds to forage

Ineligible Fields

  • Within 5 miles of Sacramento International Airport
  • Fields with more than 20% of field covered in standing straw or vegetation greater than 4 inches tall

Planning Recommendations:

  • Most field crops are suitable, including but not limited to wheat and other cereal grains, garbanzo beans, tomatoes, potatoes, sunflower, safflower, corn, rice, or fallow fields
  • If multiple fields (in close proximity) are available for flooding, it is beneficial to stagger the flood-up by 1-2 weeks; if only one field is available, consider splitting it into two or more sections with cross-field berms and flooding each section 1-2 weeks apart

Why is this program important?

Millions of ducks, geese, swans, cranes, and shorebirds depend on wetland habitat in the Central Valley, and the Sacramento-San Joaquin River Delta is an especially important place for wetland-dependent birds, particularly during drought.

With post-harvest flooding, privately owned farmland creates surrogate wetland habitat that migratory birds now depend on as they make their long journeys from Alaska to California and beyond, then back again in the spring.

Shorebirds are in steep decline, and if they don’t get a place to stop and rest during migration this year, population levels may drop even further.

Without our help, other waterbird populations that overwinter in the Delta are also likely to suffer, including the iconic sandhill crane.

Drought Relief: A make it or break it year

Why is flooding even more critical this year?

Due to severe drought conditions, habitat for migrating birds will be in even shorter supply this year, reduced to less than a third of normal levels.

Migratory birds are critical for the Central Valley ecosystem in the long term, and investing in bird populations now means investing in our crops in the future.

Maintaining a mosaic of wetlands and well-managed wildlife-friendly croplands will allow this region to continue to support these birds while benefiting other wildlife and the regional economy.