Sierra Nevada Red Fox Range- CWHR M147a [ds3356]

The updated range map for Sierra Nevada red fox (Vulpes vulpes necator) was developed using multiple sources of information (see Figure 1 of Sierra Nevada Red Fox Species Habitat Model Metadata: https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=245187). Using the historic range described in Grinnell et al. (1937) in The Mammals of California as a foundation, we refined the boundary using contemporary Sierra Nevada red fox occurrence records and habitat suitability modeling to describe the updated Range (See Appendix 1 and 2 of Sierra Nevada Red Fox Species Habitat Model Metadata: https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=245187). 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.本内华达山脉红狐（Vulpes vulpes necator）的更新分布范围图，是通过多源信息编制完成的（详见《内华达山脉红狐物种栖息地模型元数据》图1：https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=245187）。 本研究以Grinnell等（1937）发表于《加州哺乳动物》一书中的历史分布范围为基础，结合当代内华达山脉红狐出现记录与栖息地适宜性模型对分布边界进行修正，以得到更新后的分布范围（详见《内华达山脉红狐物种栖息地模型元数据》附录1、2：https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=245187）。 加州野生动物栖息地关系（California Wildlife-Habitat Relationships, CWHR）物种分布数据集，代表了加州境内各物种当前的最大地理分布范围。该分布范围最初由物种领域专家于30余年前以1:500万比例尺划定，后逐步以1:100万比例尺进行修订。 物种出现数据被用于界定物种分布范围，但分布范围多边形可能会超出某一特定物种现存出现数据的边界。在绘制分布边界时，加州鱼类与野生动物部（California Department of Fish and Wildlife, CDFW）倾向于“宁多勿缺”的原则。这意味着，即便因调查力度不足而未获得确认的出现记录，CDFW也可基于专家知识或其他可用信息，将相关区域纳入分布范围。 分布范围多边形超出出现数据的程度因物种而异，取决于各物种的扩散能力、扩散模式及其他生态与生活史特征。分布范围多边形的边界划定会综合考量上述因素，并与标准化边界对齐，包括全国水文数据集（National Hydrography Dataset, NHD）、美国农业部（United States Department of Agriculture, USDA）生态区或其他具有生态意义的划分单元，如海拔等高线。 尽管CWHR分布范围旨在代表物种当前的分布范围，但一旦某一区域被纳入CWHR的物种分布范围，即便数十年内未出现记录，该区域仍会保留在分布范围内。除非专家指出，某区域经多次调查后已连续多年未被占据，或被认定不再适宜物种生存且难以再次被定植，否则该区域不会被从分布范围多边形中移除。 需要特别说明的是，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包含了物种实际不会出现的区域。就此而言，分布范围多边形是对物种潜在分布区域的粗略概括。 本数据集可从CDFW官网下载：https://www.wildlife.ca.gov/Data/CWHR。 本次分布范围制图与物种栖息地建模工作由RADMAP团队整合了以下数据源完成。各目标类群的位置数据（如适用）从以下列表中提取。BIOS数据集以其“ds”编号标注，可通过CDFW的BIOS浏览器查询：https://wildlife.ca.gov/Data/BIOS。具体数据源包括：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，以及其他可获取的CDFW或合作方数据。