Least Tern Range - CWHR B234 [ds1507]

<div style='text-align:Left;'><div><div><p style='margin:0 0 0 0;'><span><span>CWHR species range datasets represent the maximum current geographic extent of each species within California. Ranges were originally delineated at a scale of 1:5,000,000 by species-level experts more than 30 years ago and have gradually been revised at a scale of 1:1,000,000. Species occurrence data are used in defining species ranges, but range polygons may extend beyond the limits of extant occurrence data for a particular species. When drawing range boundaries, CDFW seeks to err on the side of commission rather than omission. This means that CDFW may include areas within a range based on expert knowledge or other available information, despite an absence of confirmed occurrences, which may be due to a lack of survey effort. The degree to which a range polygon is extended beyond occurrence data will vary among species, depending upon each species’ vagility, dispersal patterns, and other ecological and life history factors. The boundary line of a range polygon is drawn with consideration of these factors and is aligned with standardized boundaries including watersheds (NHD), ecoregions (USDA), or other ecologically meaningful delineations such as elevation contour lines. While CWHR ranges are meant to represent the current range, once an area has been designated as part of a species’ range in CWHR, it will remain part of the range even if there have been no documented occurrences within recent decades. An area is not removed from the range polygon unless experts indicate that it has not been occupied for a number of years after repeated surveys or is deemed no longer suitable and unlikely to be recolonized. It is important to note that range polygons typically contain areas in which a species is not expected to be found due to the patchy configuration of suitable habitat within a species’ range. In this regard, range polygons are coarse generalizations of where a species may be found. This data is available for download from the CDFW website: </span></span><a href='https://www.wildlife.ca.gov/Data/CWHR' style='text-decoration:underline;' rel='nofollow ugc'><span style='text-decoration:underline;'>https://www.wildlife.ca.gov/Data/CWHR</span></a><span>.  </span></p><p style='margin:0 0 0 0;'><span /></p><p style='margin:0 0 0 0;'><span>The following data sources were collated for the purposes of range mapping and species habitat modeling by RADMAP. Each focal taxon’s location data was extracted (when applicable) from the following list of sources. BIOS datasets are bracketed with their “ds” numbers and can be located on CDFW’s BIOS viewer: </span><a href='https://wildlife.ca.gov/Data/BIOS' target='_blank' style='text-decoration:underline;' rel='nofollow ugc noopener noreferrer'><span>https://wildlife.ca.gov/Data/BIOS</span></a><span>. </span></p><ul><li><p style='margin:0 0 0 0;'><span><span>California Natural Diversity Database, </span></span></p></li><li><p style='margin:0 0 0 0;'><span><span>Terrestrial Species Monitoring [ds2826], </span></span></p></li><li><p style='margin:0 0 0 0;'><span><span>North American Bat Monitoring Data Portal, </span></span></p></li><li><p style='margin:0 0 0 0;'><span><span>VertNet, </span></span></p></li><li><p style='margin:0 0 0 0;'><span><span>Breeding Bird Survey, </span></span></p></li><li><p style='margin:0 0 0 0;'><span><span>Wildlife Insights, </span></span></p></li><li><p style='margin:0 0 0 0;'><span><span>eBird, </span></span></p></li><li><p style='margin:0 0 0 0;'><span><span>iNaturalist, </span></span></p></li><li><p style='margin:0 0 0 0;'><span>other available CDFW or partner data.</span></p></li></ul></div></div></div>

Tags: Auth_CDFW, CAOpenData, CDFW, California Department of Fish And Wildlife, California Natural Resources Agency, DS1507_20260324_wm, Least Tern, Sternula antillarum, bird, habitat, natural resources, species, wildlife
Organization: California Department of Fish and Wildlife