Counties where the Bald Eagle
can be found are in black.
Interior Least Tern Sterna antillarum
Status: Endangered
Description: Very small - at eight
and one-half to nine and one-half inches – the interior least tern
has a black cap and black line through the eye when in breeding
plumage. They have a deep forked tail with the outer tail feathers
being white. During winter the adults have a blurred head pattern
with mixed black and white feathers.
Habitat and Habits: The interior lease tern, like the piping
plover, nests on sandbars and barren areas along rivers. The nests
are shallow depressions. The normal clutch size is three eggs. The
interior least tern usually nests in small colonies. Nesting occurs
from early June through early August. Incubation is about 20 days
and the chicks fledge about 20 days after hatching. Terns feed on
small fish and crustaceans.
Distributions: Nesting occurs in a broad portion of the
central United States. In Iowa the interior least tern currently
nests at two sites – one near Council Bluffs and one near Sioux
City. Both sites are fly-ash deposits from power plants.
Conservation Efforts: MidAmerican Energy Company has worked
with the Iowa Department of Natural Resources to protect the Iowa
nesting areas on their property. Monitoring of nesting success has
helped to identify additional protection measures for the areas.
Reason for Listing: The loss of nesting habitat along rivers
due to construction of reservoirs, channelization and changes in
water flows has caused the decline. Construction of dams for
irrigation and navigation has inundated nesting habitat and altered
natural flows of the river. Previously, periodic flooding in the
spring built new sandbars, and water levels dropped prior to
nesting. Disturbance by people and domestic animals has also
contributed to reduced nesting success.
Funding Provided
by U.S. Environmental Protection Agency and
