DOI: 10.6078/d1w70r
title: Mammalian resilience to megafire in western U.S. woodland savannas

description: Increasingly frequent megafires, wildfires that exceed the size and
 severity of historical fires, are dramatically altering landscapes and
 critical habitats across the world. Across the western U.S., megafires
 have become an almost annual occurrence, but the implications of these
 fires for the conservation of native wildlife remain relatively unknown.
 Woodland savannas are among the world’s most biodiverse ecosystems and
 provide important food and structural resources to a variety of wildlife,
 but they are potentially threatened by megafires. Understanding the
 resistance and resilience in wildlife assemblages following these extreme
 perturbations can help inform future management interventions that limit
 biodiversity loss due to megafire. We assessed the resilience of a
 woodland mammal community to the short-term impacts of megafire.
 Specifically, we utilized a 5-year camera trap data set (2016-2020) from
 the Hopland Research and Extension Center to examine the impacts of the
 2018 Mendocino Complex fire, California’s largest recorded wildfire at the
 time, on the distributions of 9 observed mammal species. We used
 single-species occupancy models to quantify the effect of megafire on
 species’ space use and a multi-species occupancy model for robust
 estimates of fire’s impacts on species diversity across space and time.
 Megafire had a strong, negative effect on mammalian occupancy and activity
 directly following wildfire, but most species showed high resiliency and
 returned to were resilient and returned to activity and occupancy levels
 comparable to unburned sites by the end of the study period. Following
 fire, species richness was highest in burned areas that retained some
 canopy cover. Change in habitat use following wildfire varied by species:
 several species temporarily reduced their use of severely burned areas,
 while others became more active in those areas. Fire management that
 prevents large-scale canopy loss is critical to providing refugia for
 vulnerable species immediately following fire in oak woodlands, and likely
 other mixed-forest landscapes.
description: We conducted our study at the 5,300-acre U.C. Hopland Research
 and Extension Center (HREC) in Mendocino County, northern California
 (39°00′ N, 123°04’ W). The HREC ecosystem is composed of a diverse range
 of habitat types including grassland, oak woodland, and shrubland
 (chaparral). HREC is situated at an intersection of wildlands and
 ranchlands; it provides habitat for a diverse group of wildlife and serves
 as pastoral land for people and livestock. The region is characterized by
 a Mediterranean climate, with mild seasons and rains in the
 winter. On July 27, 2018, the 2018 River Fire, part of
 the much larger 2018 Mendocino Complex fire, burned over 3,400 acres of
 the 5,300-acre Hopland Research and Extension Center. At the time, the
 Mendocino Complex Fire was the largest fire in California’s recorded
 history, burning 459,123 acres. The scale and severity of this fire
 contrasted the historical fire regime in this region which is
 characterized by frequent, cooler fires in woodlands and infrequent, more
 severe burns in shrubland habitats (Syphard and Keeley, 2020).
 We established a grid of 36 motion-sensor trail cameras (Reconyx
 Hyperfire HC600), and, for this study, extracted photos taken from March
 2016 to December 2020. We placed cameras at the centroid of hexagonal grid
 cells, where each camera was positioned 750 m apart from its six
 neighbors. At each grid cell center, we placed a camera at the most
 suitable location (e.g., game trails) within 50 m of the centroid to
 maximize the detection probability of species 1m above the ground. We
 programmed cameras to take 3 photos per trigger. Of the 36 total cameras,
 25 were within the fire perimeter of the 2018 River Fire. Seven of these
 cameras were not operational following the fire and were replaced when
 conditions were safe to do so in August 2018. For this reason, and due to
 a natural increase in biodiversity detected in the fall months due to
 concurrent acorn masting, we restrict our sampling window for analyses to
 October 1st - November 30th for each year. The species
 in all collected images were classified by two independent observers who
 were members of the Brashares Lab at the University of California -
 Berkeley. We created species record tables for each year from these
 cataloged images using the ‘camtrapR’ package in R (Niedballa et al.,
 2016; Team, R. C, 2020). To create independent detections for analyses, we
 aggregated images of the same species and site using a 15-minute quiet
 period. For this study, we modeled occupancy for the 9
 mammal species with 10 or more independent detections across the entire
 study period: black bear (<em>Ursus americanus</em>), bobcat
 (<em>Lynx rufus</em>), coyote (<em>Canis
 latrans</em>), black-tailed deer (<em>Odocoileus hemionus
 columbianus</em>), gray fox (<em>Urocyon
 cinereoargenteus</em>), western gray squirrel (<em>Sciurus
 griseus</em>), black-tailed jackrabbit (<em>Lepus
 californicus</em>), raccoon (<em>Procyon lotor</em>),
 and striped skunk (<em>Mephitis mephitis</em>).
description: This is a repository containing the data described in the Methods
 section of Mammalian resilience to megafire in western U.S. woodland
 savannas by Calhoun et al. Data are divided across the
 following files.<br><br>- Nine detection histories of the form
 "[species]_detection_history.csv"<br>- One metadata file,
 "metadata.csv"<br>- Three other data files,
 "species_groups.csv", "cam_op.csv", and
 "species_recordtable_OctNov_15min.csv" All
 files are .csv files and can be opened with Microsoft Excel or any
 equivalent, as well as any programming language. These
 13 files are described in detail in the accompanying README, a .md file,
 which can be viewed with any plaintext reader.