The Mississippi Alluvial Valley (MAV) represents the historic floodplain and
valley of the Lower Mississippi River. It is easily the most significant winter
habitat area for mallards in North America.
The MAV was once a 24.7 million acre complex of forested wetlands interspersed
with swamps, cypress-tupelo brakes, scrub-shrub wetlands, and emergent wetlands.
This vast complex of wetlands, through which nearly 40% of North America drains,
provided wetland functions (e.g., water quality improvement) and values (e.g.,
wildlife habitat) of incalculable worth. Each winter, portions of the entire
system flooded, making several million acres of habitat available to wintering
mallards and wood ducks. Food in the form of acorns and moist soil plants
such as wild millet, were made available via winter flooding. While no wetland
system is 100% reliable or predictable in terms of annual habitat and food availability,
the MAV was likely among the most consistent and reliable habitats the birds
encountered during their annual migration.
Such is no longer the case. Approximately 80% of the forested lands in the
MAV have been cleared and converted to agriculture, including thousands of acres
that were cleared as recently as the 1970s when soybean prices made it economical
to farm very marginal, flood-prone lands. Further, natural flooding in the
MAV has been reduced by 50-90%. Hence, what was a system that provided reliable
consistent winter habitat on an annual basis, it is now a system that provides
far less habitat. Today, flooding occurs later in winter and well into the growing
season, the duration of flooding on some higher sites is far less to nonexistent,
while flooding on some lower sites occurs much longer and later each year. The
net effect of these alterations is significantly reduced availability of feeding
habitat or forested habitats that provide for other needs of birds at this time
of year, such as pair isolation and thermal refuge during cold snaps.
Projects in the MAV:
Arkansas
Mississippi
Louisiana
Missouri
Kentucky
Tennessee
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