The following is an excerpt from the U.S. Fish and Wildlife Service species status assessment report for the coastal marten (Martes caurina), Version 2.0 (July 2018); refer to this report for additional details:

4.2 Current Range and Distribution (1980–current)

All current (since 1980) verifiable marten detections were used to delineate extant population areas (EPAs) within the historical home range. The number of detections available to guide the delineation of the boundaries of the EPAs varied across the analysis area (Figure 4.2). In addition, sampling techniques varied across the range. Marten detections were buffered by 2 km and connected using a minimum convex polygon tool. Similar to methods used in the Humboldt Marten Conservation Strategy and Assessment, a 2 km buffer distance was used because most coastal marten survey and monitoring grids use a 2–km grid spacing, thus to feel confident about where animals do not occur, one would need to survey the next grid point without detections. If the total number of detections in an area was less than 5 or they were separated by greater than 5 km from other verifiable detections, the combined detections were not designated as an EPA due to the insufficient level of information to suggest a likely self–sustaining population (Slauson et al., In review, Slauson et al., In press). Because some detections did not meet this definition of a population they appear on Figure 4.3 as points but are not included in the population areas.

Based on the distributions of current verifiable marten detections and adjacent suitable habitat, we identified four EPAs within coastal Oregon and northern coastal California (Figures 4.3):

1) Central Coastal Oregon Extant Population Area (CCO_EPA)

2) Southern Coastal Oregon Extant Population Area (SCO_EPA)

3) Oregon–California Border Extant Population Area (CAOR_EPA)

4) Northern Coastal California Extant Population Area (NCC_EPA)

This dataset contains the four EPAs described in the SSA excerpt above.