Northern Spotted Owl Range - CWHR B270a [ds3261]

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: https://www.wildlife.ca.gov/Data/CWHR. 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: https://wildlife.ca.gov/Data/BIOS. California Natural Diversity Database, Terrestrial Species Monitoring [ds2826], North American Bat Monitoring Data Portal, VertNet, Breeding Bird Survey, Wildlife Insights, eBird, iNaturalist, other available CDFW or partner data.CWHR物种分布范围数据集展示了加利福尼亚州内各物种当前的最大地理分布范围。该分布范围最初于30余年前由物种专家以1:500万比例尺绘制，后续逐步以1:100万比例尺进行修订完善。物种出现记录数据被用于界定物种分布范围，但分布范围多边形（range polygons）可能会超出某一特定物种现存的出现记录数据范围。在绘制分布范围边界时，加州鱼类与野生动物局（CDFW）秉持宁含勿漏的绘制原则，即宁可过度纳入而非遗漏区域。这意味着即便某区域暂无经确认的物种出现记录（此类情况可能源于调查力度不足），CDFW仍可基于专家知识或其他可用信息，将其纳入该物种的分布范围。分布范围多边形超出出现记录数据的程度因物种而异，取决于各物种的移动性、扩散模式以及其他生态与生活史特征。分布范围多边形的边界线绘制会综合考量上述因素，并与标准化边界对齐，包括水文流域（NHD）、生态区（USDA）以及其他具有生态意义的划分界线，如海拔等高线。尽管CWHR分布范围旨在反映物种当前的分布情况，但一旦某区域被纳入CWHR的物种分布范围，即便近数十年内无该物种的记录，该区域仍会保留在分布范围中。除非专家经多次调查确认某区域已多年未被该物种占据，或判定该区域不再适宜物种生存且不太可能再次被殖民，否则该区域不会从分布范围多边形中移除。需特别说明的是，由于物种分布范围内适宜栖息地呈斑块状分布，分布范围多边形通常会包含物种实际不会出现的区域。就此而言，分布范围多边形仅是对物种潜在分布区域的粗略概括。该数据集可从CDFW官网下载：https://www.wildlife.ca.gov/Data/CWHR。以下数据源由RADMAP为分布范围制图与物种栖息地建模工作整理汇总。各目标类群的位置数据（如适用）均从以下来源提取。BIOS数据集以其“ds”编号标注，可通过CDFW的BIOS查看平台获取：https://wildlife.ca.gov/Data/BIOS。加州自然多样性数据库、陆地物种监测[ds2826]、北美蝙蝠监测数据门户、VertNet、繁殖鸟类调查、Wildlife Insights、eBird、iNaturalist以及其他可用的CDFW或合作方数据。