Sierra Nevada Red Fox (Southern Cascades DPS) Range - CWHR M147d [ds3358]

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.本数据集为内华达山脉红狐（Vulpes vulpes necator）的更新分布范围图，编制基于多源信息（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）。研究以Grinnell等人1937年发表于《加州哺乳动物》中的历史分布范围为基础，结合当代内华达山脉红狐的出现记录与栖息地适宜性模型对分布边界进行修正，以此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与附录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层级专家在30余年前以1:5000000的比例尺绘制，后续逐步以1:1000000的比例尺进行修订。 物种分布范围的界定会用到物种出现数据，但分布范围多边形可能会超出某一特定物种的现存出现数据范围。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）倾向于采用"宁多毋缺"的原则。这意味着即便某一区域暂无确认的物种出现记录（可能源于调查力度不足），CDFW仍可基于专业知识或其他可用信息将其纳入分布范围。分布范围多边形超出现有出现数据的程度会因物种而异，取决于各物种的扩散能力、扩散模式以及其他生态与生活史因素。分布范围多边形的边界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（国家水文数据集National Hydrography Dataset, NHD）、生态区（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方式（如海拔等高线）。 尽管CWHR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，即便后续数十年内无相关物种出现记录，该区域仍会被保留在分布范围多边形中。除非专家经多次调查确认某区域已多年未被物种占据，或判定该区域不再适宜物种栖息且不太可能被重新定居，否则该区域不会被从分布范围多边形中移除。需要注意的是，分布范围多边形通常包含一些理论上不会有物种出现的区域，这是因为物种分布范围内的适宜栖息地呈斑块状分布。就此而言，分布范围多边形是对物种可能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。 本次分布范围制图与物种栖息地建模由RADMAP团队整合了以下数据源。针对每个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浏览器查阅：https://wildlife.ca.gov/Data/BIOS。具体包括：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，以及其他可用的CDFW或合作机构数据。