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Section 7 Consultation:
Operation and Maintenance of the Upper Mississippi River 9-Foot Channel
Interior Least Tern
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-Small member of the tern family that requires open expanses of sand or pebble beaches along river banks and reservoirs for nesting. Foraging habitat includes side channels, sloughs and shallow-water habitats adjacent to sand islands and must be located within a short distance of a colony for successful reproduction.
-The interior least tern historically bred along the Mississippi River as far north as Lee County, Iowa. Currently, the breeding range along the Mississippi River extends to St. Louis, Missouri.
-The species' decline is attributed to the large-scale transformation of interior river systems for navigation, flood control, hydropower and irrigation which has eliminated much of the least terns' nesting habitat (e.g., sandbar habitat in the Lower Mississippi River declined by 33% from 1948 to 1994).
-Other causes of decline include water level fluctuations, human disturbance, pollutants and predation.
- Least tern populations along the Lower Mississippi River and Middle Mississippi River have increased; however, this increase cannot be attributed to high reproductive productivity. It is thought to be the result of immigration.
-While the Mississippi River appears to have a large amount of sandbar habitat, much of this habitat is not likely available to least terns for nesting and may not be located near suitable foraging habitats.
Project Effects to the Species
Continued alteration and disruption of dynamic, natural river processes that create and maintain habitat.
Continued loss of habitat quality, quantity and
diversity resulting in:
Continued transference and homogenization of contaminants
Over the 50 year project life, sandbar nesting habitat and foraging habitat are anticipated to decline in quantity and quality as a result of continued O&M. This represents significant habitat modification significantly impairing essential behavioral patterns of least terns in the MMR.
and Prudent Measures (RPMs)
Dredge disposal techniques will be evaluated to examine opportunities and develop recommendations for restoring/enhancing sandbar and aquatic habitat. Recommendations to be implemented where feasible and appropriate.
Utilize existing authorities to reduce the accretion of existing and/or newly established sandbars to the bankline and to reduce woody vegetation colonization.
Last updated: April 14, 2015