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How Does a Location Qualify
Four criteria were established to identify IBAs in California through 2004. For more information on each criteria, click on the link below.
For an overview of general state criteria standards and for national and global level criteria, visit: http://www.audubon.org/bird/iba/criteria.html. All California IBAs are being evaluated and prioritized based on their ornithological significance from a regional/global perspective based on standardized criteria developed by National Audubon in partnership with BirdLife International.
IBA Category P [top]SITES WITH OVER 1% of GLOBAL or 10% of CALIFORNIA POPULATION OF ONE OR MORE SENSITIVE TAXA (breeding and/or wintering) Description: These numbers were difficult to pin down, especially for rapidly-declining species (e.g. Light-footed Clapper Rail) and those difficult to survey (e.g. Marbled Murrelet). Every effort was made to use recently published, peer-reviewed sources to arrive at a good estimate, and even this was possible only for a few taxa. This proportion may include only breeding or wintering populations, or may refer to the entire population in sedentary species. Most IBAs identified support significant populations of non-sensitive taxa (e.g. certain waterfowl or shorebird species), and to identify all of these would be a near-impossible task. The exception to this was Long-billed Curlew, which the report treats as sensitive only if breeding, but whose recent population estimate (Brown et al. 2001) has allowed for a calculation of a population threshold for wintering birds as well. Taxa restricted to just a handful of breeding or wintering sites in California for which a population estimate would not be useful for determining population thresholds were marked “limited range”. The regular occurrence of any number of individuals of these taxa were generally enough to hit the threshold numbers for global and state populations.
IBA Category L [top]
SITES CONTAINING MORE THAN 9 SENSITIVE SPECIES Description: “Sensitive species” were considered to be all those listed as threatened or endangered by state and/or federal agencies (CFDG 2000), as well as most of the species under consideration as California Species of Special Concern (CFDG and PRBO 2001). A handful of taxa treated as Bird Species of Special Concern were not counted as Sensitive Species here, either because of the lack of precision in their ranges (Modesto Song Sparrow, T. Gardali, pers. comm.), or because their ranges are so large that their inclusion would probably not contribute appreciably to the analysis (Olive-sided Flycatcher, California Horned Lark). To download a list of species listed as State or Federally Threatened/Engangered or as a Species of Special Concern (updated in Feb. 2006): http://www.dfg.ca.gov/bdb/html/animals.html The conservation consortium “Partners-in-Flight” has developed a list of “priority” species absent from threatened/endangered species lists that are of conservation concern for a variety of reasons, such as having small global ranges (Pashley et al. 2000). National Audubon Society has developed this list into its “WatchList” program, a later incarnation of the “Blue List”. Many of these species are treated in the California IBA report as sensitive species. However, those felt by various advisors to be too widespread and common (e.g. Short-billed Dowitcher, California Thrasher) or that occurring marginally in California and for short periods of time (e.g. Least Storm-Petrel) were not included. Finally, the IUCN (International Union for the Conservation of Nature) has produced its own list of vulnerable species, published through BirdLife International (2000). Eleven of the 13 taxa on their “Red List” that occur in California area treated in the IBA report; the other two are either found far out at sea (Black-footed Albatross, Craveri’s Murrelet) or are clearly thriving in the U.S. portion of their range (Heerman’s Gull). Unlike IBA programs in other states, sites were not included for simply supporting species of conservation concern – California has too many and they occur too widely. A concerted effort was made to exclude as “present” taxa if they that only occur as transients when relatively plastic in their ecological requirements (e.g. Willow Flycatcher), or those that only occur on foraging runs from distant breeding locales (e.g. gulls, terns). For example, Willow Flycatcher would only be considered “present” only if breeding or suspected of breeding within the given IBA. In two special cases, Sage Sparrow and Cactus Wren, allcoastal-slope populations were included, since both are widespread in the desert and rare and declining elsewhere in the state. The current presence of sensitive species at the various IBAs was determined through published sources where possible, but was confirmed principally via interviews with local birders. Various statewide (e.g. Grinnell and Miller 1944, Grenfell and Laudenslayer 1983, Small 1994) and regional references (e.g. Garrett and Dunn 1981, Unitt 1984) were consulted for this information prior to the interviews, though not generally cited specifically within the site accounts.
IBA Category S [top]
SITES WITH OVER 10,000 SHOREBIRDS POSSIBLE ON A 1-DAY COUNT Description: Somewhat arbitrary numbers, but ones that seem to identify the top sites fairly well (i.e. seem neither particularly low nor high). Data were drawn from several sources, especially surveys done by PRBO (e.g. Page et al. 1999).
IBA Category W [top]
SITES WITH OVER 5,000 WATERFOWL POSSIBLE ON A 1-DAY COUNT Description: Audubon Christmas Bird Count data were a major source of information for this criterion. One variance from earlier iterations of the IBA program (and ABC’s effort) is the exclusion of waterfowl that are only passing by (e.g. coastal promontories). Text on this page has been excerpted from “Important Bird Areas of California”. Recommended Citation: Cooper, D.S. 2004. Important Bird Areas of California. Audubon California. 286 pp. Available (online) at: http://ca.audubon.org/iba/index.shtml. Retrieved [insert date]. |
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