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Person

Emily E Perkins

Geographer
Western Ecological Research Center

Email: eperkins@usgs.gov
Office Phone: 619-225-6440
Fax: 619-225-6436
ORCID: 0000-0002-6286-3480

Location
San Diego State University
4165 Spruance Road
Suite 200
San Diego , CA 92101
US

Supervisor: Barbara E Kus
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This habitat model was developed to delineate suitable habitat for coastal cactus wren (Campylorhynchus brunneicapillus) in southern California. A primary purpose of the model is to identify potential restoration sites that may not currently support cactus patches required by wrens, but which are otherwise highly suitable. These are areas that could be planted with cactus to increase wren populations, an important management objective for many land managers. We used the Partitioned Mahalanobis D2 modeling technique to construct alternative models with different combinations of environmental variables. Variables were calculated at each point in the center of a 150 m x 150 m cell in a grid of points across the landscape....
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This habitat model was developed to delineate a sampling frame for regional monitoring of coastal California gnatcatchers (Polioptila californica californica) to determine: 1) percent area occupied (PAO) in high and very high suitability habitat across conserved lands and participating military lands in the U.S. range in southern California; 2) changes in PAO over time; and 3) extinction and colonization rates. One purpose of the model is to identify areas recovering from disturbance, such as wildfire, that may not currently support coastal sage scrub vegetation used by coastal California gnatcatchers, but are otherwise highly suitable. In this way, we can monitor gnatcatcher occupancy associated with habitat changes...
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Drainage areas (or watersheds) were calculated for each stream segment in the National Hydrography Dataset High Resolution Plus Beta (NHD HR Plus Beta) using non-end junction points and the provided hydrologically enforced Digital Elevation Model (DEM). The DEM was used to create a flow direction raster. The pour points used were determined from junction points at each stream intersection excluding stream ends (i.e. channel heads are not included). Watershed calculations were automated using the ArcGIS "watershed" tool and then edited manually for accuracy. In western San Diego County (non-desert) there were 39,980 drainage areas calculated. The percent impervious in each watershed was calculated using the National...
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Shrublands have seen large changes over time due to factors such as fire and drought. As the climate continues to change, vegetation monitoring at the county scale is essential to identify large-scale changes and to develop sampling designs for field-based vegetation studies. This dataset contains two raster files that each depict the height of vegetation. The first layer is restricted to actively growing vegetation and the second is restricted to dormant/dead vegetation. Both layers cover open space areas in San Diego County, California. Height calculations were derived from Lidar data collected in 2014 and 2015 for the western two-thirds of San Diego County. Lidar point clouds were pre-classified into ground and...
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This habitat model was developed to identify suitable habitat for the federally-endangered least Bell’s vireo (Vireo bellii pusillus) across its current and historic range in California. The vireo disappeared from most of its range by the 1980s, remaining only in small populations in southern California. Habitat protection and management since the mid-1980s has led to an increase in southern California vireo populations with small numbers of birds recently expanding into the historic range. Predictions from this model will be used to focus surveys in the historic range to determine where vireos are recolonizing and to track the status and distribution of populations over time. We used the Partitioned Mahalanobis...
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