Martens are a species of special concern in California, and are considered to be a. Management Indicator Species by the U.S. Forest Service. â« Resting habitat is ...
Resting structure and location use by martens, Lassen National Forest, CA Introduction Western martens (Martes caurina)* are members of the weasel family (Mustelidae), and are associated with structurally complex, high elevation late-seral coniferous forests in the Cascade and Sierra Nevada mountain ranges (Spencer et al. 1983, Zielinski et al. 2005). Martens are a species of special concern in California, and are considered to be a Management Indicator Species by the U.S. Forest Service. Resting habitat is a key component of suitable habitat for martens, and is defined at four spatial scales (stand, site, structure, and location) by Slauson and Zielinski (2009). Resting structures are commonly comprised of live trees and deadwood features, including snags, stumps, and logs (Slauson and Zielinski 2009). These structures are large in diameter, more decadent, and used more frequently than structures predicted by availability (Raphael and Jones 1997), similar to our experience on the Lassen National Forest (Table 1; Linnell et al. 2011). Martens use resting structures between periods of activity, to avoid predators (Buskirk 1992) and to minimize energetic costs (Buskirk et al. 1989).
Matthew S. Delheimer, Katie M. Moriarty, Mark A. Linnell, Clinton W. Epps Oregon State University, Corvallis, OR. Table 1: Comparison of sample size (n) and tree size in diameter at breast height (DBH, inches) for actual above-ground structures (estimated DBH) used by western martens (Martes caurina) and randomly-sampled structures (measured DBH) on the Lassen National Forest, CA. Standard deviation (SD) shown in parentheses.
n 11 5 4 1 1 19 13 5 1
Live Trees Red Fir White Fir Jeffery Pine Western Juniper Snags Red Fir White Fir Jeffery Pine
Actual Sites DBH (SD) 34.55 (8.7) 36.4 (9.3) 30 (5.9) 30 (-) 48 (-) 36.53 (8.3) 37.3 (9.7) 33.8 (3.9) 40 (-)
Random Sites n DBH (SD) 414 22.12 (8.7) 189 23.1 (8.5) 211 21.05 (8.8) 14 25.07 (7.9) 0 N/A (-) 56 22.73 (10.5) 40 24.38 (10.5) 16 18.61 (9.6) 0 N/A (-)
Martens conserve energy by using resting structures that provide thermoregulatory benefits in response to daily and seasonal variability in weather conditions (Taylor and Buskirk 1994). Our objective was to investigate marten resting structure and location use in respect to season, position (relative to surface), and weather (ambient air temperature).
Table 2: Resting habitat use, including structure (columns) and location (rows), by western martens (Martes caurina) on the Lassen National Forest. Table rows are divided by aboveand below-surface locations.
*previously referred to as American marten (M. americana)
Study Area and Methods
We conducted research at two sites on the Lassen National Forest (Figure 1); elevation at these sites ranged from 1500 to 2650m. Climate at these sites is typified by warm, dry summers and cold, wet winters; annual precipitation averages 100-150cm, mostly as snow (Bailey 1995, http://www.fs.fed.us/r5/projects/ecoregions/m261m.htm). We opportunistically located VHF-collared adult martens in resting habitat from 2009-2012.
We evaluated resting habitat at two spatial scales: - resting structure, defined as the habitat element (e.g. snag) in which a marten rests - resting location, defined as the place within the resting structure where the marten rests (Slauson and Zielinski 2009) We defined seasons as snow (>1m snow cover) and snow-free (
