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Mississippi Alluvial Valley – More Information

Background information on the Mississippi Alluvial Valley region, a DU conservation priority area
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Importance to other wildlife

The forested wetland habitat that occurred in the MAV provided substantial habitat for a unique array of wildlife. Rivers in the MAV at one time provided habitat for some of the most diverse, abundant freshwater mussel populations on the continent (Christian 1995). Today, due to alterations in hydrology and increased sediment loads from agricultural lands, several mussel species in the MAV are endangered or have become extirpated or extinct. The complex of forested wetlands, sloughs and rivers supports over 60 species of fish, many of which have sport or commercial value (Hoover and Kilgore 1997). The life histories of many species are intricately related to the natural hydrology of the system. For example, some species key on peak riverine flood flows to stimulate spawning activities, whereas others use flooded forest as nursery habitat. Timing and duration of winter and spring flooding are important influences on fish population dynamics (Hoover and Kilgore 1997).

The forests of the MAV also supported a diverse resident and migrant avifauna in addition to waterfowl. Several species of neotropical migrant passerines, woodpeckers, and raptors likely had population centers, or source areas, centered in the MAV. Among these were many area-sensitive species that likely were common to abundant in the pre-agricultural MAV. For example, species such as the cerulean warbler and Swainson's warbler likely occupied much of the northern and entire MAV respectively, whereas currently they exist only in a few isolated, large remnants of forest (Hunter et al. 1992). The ivory-billed woodpecker and Carolina parakeet, once likely residents of much of the MAV, are extinct. The swallow-tailed kite, an area-sensitive raptor that once occurred well into the mid-MAV, now is restricted as a breeding bird to the Atchafalaya Delta in the extreme southern portion of the MAV. The future of these remaining populations is uncertain, particularly because the ultimate effects of relatively recent large-scale clearing and resultant fragmentation are not completely clear or immediate (Faaborg et al. 1992).

As with birds, several species of mammals have suffered population declines or extirpation as a result of landscape-scale changes to the forest of the MAV. The panther has been extirpated from the MAV for several decades. The Louisiana black bear, a subspecies of the American black bear, is a federally listed endangered species whose decline is directly linked to deforestation and fragmentation. The future of this subspecies may well depend on our ability to reforest and reduce fragmentation within its range (Black Bear Conservation Committee 1992). Forested wetlands in the MAV also provide habitat for at least 7 species of bats. Bat populations have never been monitored, but some species in the MAV appear to rely extensively upon large, hollow cypress trees for nursery habitat, and some may be area sensitive. Bats appear to share their requirement for such trees with black bears. It is very likely that bat populations in the MAV were negatively affected by conversion of forest to agriculture, though to what degree remains unknown.

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