Species History
Listed as endangered in 1985;
Recovery Plan developed in 1990
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:
• Reduced availability
of suitable nesting habitat
• Reduced availability
of foraging habitat
• Reduced availability
and quantity of forage food
• Increased incidence
of predation
Continued transference and homogenization of contaminants
• Potentially impaired
reproductive success
• Potentially reduced
bird health
Why
Incidental Take?
Take is defined as to harass, harm, pursue, hunt, shoot,
wound, kill, trap, capture or collect, or attempt to engage in any such
conduct.
Harm is further defined by the Service to include significant habitat
modification or degradation that results in death or injury to listed
species by significantly impairing essential behavioral patterns, including
breeding, feeding or sheltering.
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.
Reasonable
and Prudent Measures (RPMs)
Channel
training structure maintenance projects will incorporate modifications
to maintain least tern nesting habitat
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.
