Rangewide occupancy and post-fire recovery of California Gnatcatchers in southern California, 2020

Data presented are results of surveys for California Gnatcatchers and vegetation sampling conducted in 2015, 2016, and 2020 to address two inter-related questions: (1) How have gnatcatchers and their habitat recovered in areas burned by wildfires in 2003, 2007, and 2014?, and (2) What is the current regional occupancy of gnatcatchers throughout their southern California range? Data for the post-fire study were collected in 2015, 2016, and 2020, while the regional occupancy survey was conducted in 2016, and 2020. In 2015, Gnatcatcher occupancy as a function of fire history was derived from 324 points in the following fire categories: 2003-2006 (106 points), 2007-2010 (111 points), and 2011-2014 (107 points). In 2016, points representing a fourth category, unburned (i.e. prior to 2002) were added to the design, with the following numbers of points surveyed per category: 2003-2006 (106 points), 2007-2010 (109 points), 2011-2014 (106 points), and unburned (103 points). In 2020 a fifth fire category was added (2015-2019) which changed the sample sizes for the other fire categories: 2003-2006 (102 points), 2007-2010 (106 points), 2011-2014 (95 points), 2015-2019 (25 points), unburned (96 points). All post-fire study points were in San Diego County. The regional occupancy surveys included 334 points in 2016 and 327 points in 2020 throughout southern California. The post-fire and regional datasets are not mutually exclusive, with some points serving in both analyses. Vegetation data were collected at each point in 2015, 2016, and 2020 to facilitate analyses identifying habitat correlates of California Gnatcatcher occurrence.