U.S. Fish & Wildlife Service
What is it?
When the Fish and Wildlife Service
proposes a listing under the Endangered
Species Act, we are required to consider
whether there are geographic areas that
are essential to conserve the species. If
so, we may propose designating these
areas as critical habitat.
Here are answers to some of the most
frequently asked questions about critical
What is critical habitat?
Critical habitat is the specific areas
within the geographic area, occupied by
the species at the time it was listed, that
contain the physical or biological features
that are essential to the conservation
of endangered and threatened species
and that may need special management
or protection. Critical habitat may also
include areas that were not occupied by
the species at the time of listing but are
essential to its conservation.
An area may be excluded from critical
habitat designation based on economic
impact, the impact on national security,
or any other relevant impact, if we
determine that the benefits of excluding
it outweigh the benefits of including it,
unless failure to designate the area as
critical habitat may lead to extinction of
Critical habitat designations affect only
Federal agency actions or federally
funded or permitted activities. Critical
habitat designations do not affect
activities by private landowners if
there is no Federal “nexus”—that is,
no Federal funding or authorization.
Federal agencies are required to avoid
“destruction” or “adverse modification”
of designated critical habitat. The ESA
requires the designation of “critical
habitat” for listed species when “prudent
What provisions of the Endangered
Species Act relate to critical habitat?
To protect endangered and threatened
species, the Endangered Species Act
makes unlawful a range of activities
involving such species without a permit
for purposes consistent with conservation
goals of the Act. These activities include
take, import, export, and interstate or
foreign commerce. “Take” includes kill,
harm, harass, pursue, hunt, capture, or
collect or to attempt to engage in any
The Act requires Federal agencies
to use their authorities to conserve
endangered and threatened species and
to consult with the Fish and Wildlife
Service about actions that they carry
out, fund, or authorize to ensure that
they will not destroy or adversely modify
critical habitat. The prohibition against
destruction and adverse modification of
critical habitat protects such areas in the
interest of conservation.
How does the Fish and Wildlife Service
determine areas to designate as critical
Biologists consider physical and
biological features that the species
needs for life processes and successful
reproduction. These features include:
n space for individual and population
growth and for normal behavior;
About 90 miles northwest of Las Vegas,
Nevada, Ash Meadows National Wildlife
Refuge was established to protect endangered
species in uplands and spring-fed wetlands.
Plants and animals found nowhere else
in the world are at home here, including
the endangered Devil’s Hole pupfish, the
endangered Amargosa niterwort (a plant),
and a threatened aquatic beetle species, the
Ash Meadows naucorid.
Photo of Ash Meadows National Wildlife Refuge by Mike Bender, USFWS
Photo of the Devil’s Hole pupfish by Olin Feurerbacher, USFWS
n cover or shelter;
n food, water, air, light, minerals,
or other nutritional or physiological
n sites for breeding and rearing
offspring, germination, or seed dispersal;
n habitats that are protected from
disturbances or are representative of the
historical geographical and ecological
distributions of the species.
What is the process for designating critical
The Service may propose to list a species
and concurrently propose to designate
critical habitat, or it can address a
species’ critical habitat up to a year
after the date of its listing. The Service
proposes a critical habitat designation,
publishing it in the Federal Register
and requesting public comments. We
may modify a proposal as a result of
information provided in public comments.
We base our final designation of critical
habitat on the best scientific data
available, after taking into consideration
the probable economic and other impacts
of the designation. After reviewing the
comments, the Service responds to them
and publishes a rule, including final
boundaries, in the Federal Register.
Are Federal agencies required to consult
with the Fish and Wildlife Service outside
critical habitat areas?
Yes, even when there is no critical
habitat designation, Federal agencies
are required fulfill their conservation
responsibilities by consulting with
the Fish and Wildlife Service if their
actions “may affect” listed species. The
requirement helps to ensure that Federal
agencies do not contribute to the decline
of endangered and threatened species or
their potential for recovery.
What is the purpose of designating
Designating areas as critical habitat
does not establish a refuge or sanctuary
for a species. Critical habitat is a tool
to guide Federal agencies in fulfilling
their conservation responsibilities by
requiring them to consult with the Fish
and Wildlife Service if their actions may
“destroy or adversely modify” critical
habitat for listed species. A critical
habitat designation helps to protect
areas—occupied and unoccupied—
necessary to conserve a species. Critical
habitat has value in requiring the Service
to gather more detailed information
about a species than what is required for
listing, thereby increasing knowledge
to share with Federal agencies—and, in
turn, increasing their effectiveness.
The areas shown on critical habitat maps
are often large. Are all the areas within
the mapped boundaries considered
No. Our rules typically exclude developed
areas such as buildings, roads, airports,
parking lots, piers, and similar facilities.
Accompanying text describes those
Critical habitat is designed to protect
the essential elements of physical and
biological features of a landscape and
essential areas in the appropriate
quantity and spatial arrangement that a
Myths & Realities
Does designating critical habitat mean no further development can occur?
No. A critical habitat designation does not necessarily restrict further
development. It is a reminder to Federal agencies of their responsibility to
protect the important characteristics of these areas.
Does a critical habitat designation affect all activities that occur within the
No. Only activities that involve a Federal permit, license, or funding, and are
likely to destroy or adversely modify critical habitat will be affected. If this is
the case, we will work with the Federal agency and landowners—including
private landowners-- to amend their project to enable it to proceed without
adversely affecting critical habitat. Most Federal projects are likely to go
forward, but some may be modified to minimize harm.
species needs to survive and reproduce.
Why are large areas shown on critical
habitat maps if the entire area is not
actually considered critical habitat?
In some cases, precisely mapping
critical habitat boundaries is impractical
or impossible, because the required
descriptions for these precise boundaries
would be unwieldy.
Does the Act require consideration of
economic impacts as part of designating
Yes. The Service is required to consider
potential economic impacts, as well
as any other benefits or impacts of
designating critical habitat—and
may exclude an area if the benefits of
excluding it outweigh the benefits of
including it unless that would result in
the extinction of the species.
Do economic considerations affect
decisions to list species as endangered or
No, the Act requires listing decisions
to be made solely on the basis of the
best available scientific and commercial
What is the impact of a critical habitat
designation on economic development?
Most activities that require consultation
by Federal agencies proceed without
modification. In areas where the species
is not present, some project modifications
that would not have occurred without
the critical habitat designation may be
required. For example, the U. S. Army
Corps of Engineers may schedule a
beach renourishment project—that is
adding sand to a beach to stabilize it—
before or after the nesting season of sea
turtles to avoid harm to the sea turtles,
their eggs, or their hatchlings.
How many species have critical habitat
As of April 1, 2011, critical habitat
has been designated for 604 of the
1,372 U.S. species, subspecies, and
distinct vertebrate populations listed as
threatened or endangered.
U.S. Fish & Wildlife Service
Endangered Species Program
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