Mapping Endangered Species Habitat

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The distribution of most endangered species has not been officially defined. Surveying for the presence of many species is problematic, expensive and unreliable. The mobility of some species and even the dispersal of seeds confound efforts to define habitat. In most cases, the best estimate of current distribution comes from past sightings and current evaluations of land use in these areas. Changing land uses, including field rotations, land development and natural variables such as food supply, droughts, floods and wildfires cause many species to redistribute faster than surveys can be completed. Surveying for the current distribution of species is therefore reserved for special cases where no other approach is feasible to limit pesticide exposure to non-target species.

It is generally adequate and preferable to rely on ongoing interpretations of the best available information on species distribution rather than investing in new surveys. The best available compilation of sightings for federally listed species (and other species of special status) in California is the Department of Fish and Game's Natural Diversity Database (NDDB). Sites in the NDDB are often defined by a central point and a radius (up to one mile) that define the general area of an occurrence of a species. More precise information is used where available.

As a starting point for protecting endangered species, DPR is converting the NDDB data into a list of sections (a species-section database) where these species may be found. Within these sections, a description of habitat (where practical to define) accompanies protection strategies to limit protection strategies to areas that meet the conditions of habitat for a particular species. The species-section database includes links to the NDDB or other citations that document the sections as probable habitat. A procedure is being developed to update the species-section database as needed to ensure that the database includes sections that are necessary and sufficient for species protection.

DPR's species-section database can be readily mapped to show the overall distribution of one or more species in a county or other area of interest. However, the database may be more useful to pesticide users in the ability to support queries by section. Such queries can be used to determine:

  • 1) if there are any protected species in any user-selected section(s).
  • 2) a list of active ingredients of pesticides that have use limitations for protection of the species triggered by the user-selected section.
  • 3) the use conditions that apply to user-selected sections and active ingredients.

The results of these queries may be printed by the user to guide the application of selected pesticides in selected sections.