Criteria for Site Selection
 A
site meeting any one of the following four criteria may qualify as an IBA.
These criteria should not be considered absolute, and other factors, such as
relative importance to others sites, may be weighed in making the final site
selections.
CATEGORY 1: Sites
regularly providing habitat for significant numbers of one or more endangered,
threatened, or vulnerable species. The site
provides habitat for a number of individuals classified as globally endangered,
threatened, or vulnerable (BirdLife International list); listed as endangered,
threatened, or as a candidate for listing under the U.S. Endangered Species
Act; or species on the Partners in Flight Watch
List. Sites should be those areas where the
species rgularly occurs, or sites with suitable habitat where re-introductions
are planned. Sites should not include areas where the species occurs
irregularly, or where the species occurred historically (unless
re-introductions are under active consideration).
CATEGORY 2: : Sites
regularly prividing habitat for an endemic species, or species with restricted
ranges. The site provides habitat for one or
more endenic species, or a species with an overall range of less than 50,000
square-km (e.g., California Gnatcatcher). This includes sites containing species
with small worldwide ranges having a significant portion of their range in the
United States. At a National level, this category includes species with a
majority of their ranges restricted to a single physiographic area (e.g.,
Plumbeous Vireo).
CATEGORY 3: : Sites
regularly prividing habitat for an assemblage of species restricted to a biome
or a unique/threatened natural community type. The
site is known or thought to provide habitat for a significant component of the
group of species whose distributions are largely or wholly confined to one
biome (e.g., Chihuahuan Desert, Shortgrass Prairie); or, the site is an
exceptional representation of a characteristic natural or near- natural habitat
within an Avian Physiographic Stratum (as defined by PIF/BBS). Selection of
sites is based upon the completeness of the avian assemblage for that habitat
type. This category is meant mainly to cover relatively large areas capable of
supporting significant bird populations, especially of those bird species with
particular habitat requirements. Example: Saguaro National Park in Arizona for
the Sonoran Desert biome.
CATEGORY 4: : Sites
where birds concentrate in significant numbers when breeding, in winter, or
during migration. The site regularly provides
habitat for greater than 1% of the biogeographic population of a species. In
cases where the population size is unknown, use the threshold for similar
species with approximately the same population density. If a large group of
similar species use the area (e.g., waterfowl, seabirds), sum the percentage of
each of the species using the area to see if it adds up to 1%. This category is
meant to cover sites important because they hold high concentrations of birds
during one or more times of the year. It also covers sites that act as
migratory stopovers, "bottlenecks," and/or corridors. Corridors and "bottlenecks" refer not only to terrestrial sites, but to topographic
features that funnel birds through those sites (e.g., raptors flying overhead). The
numerical criteria are guidelines only; other factors may be considered.
Raptor migration sites: The site is a regular "bottleneck" or
migratory corridor for raptors. Seasonal totals of 10,000 raptors.
Migratory passerine sites (tentative): The site is a regular migratory stopover
or corridor for migratory landbirds (other than raptors). Concentrations refer
to seasonal totals rhater than those occurring over a brief period of time. Sites
nominated should contain exceptional numbers and/or diversity of migratory
landbirds. Tentative thresholds are 250,000 over a season or 40/ha at one time. |
