Changing climatic patterns have been affecting the western US in a variety of ways: episodic, large decreases in yearly precipitation, decreased snowpack, earlier spring snowmelt, and increased sustained winds have created a drier and more fire-prone system. Wildfires are a natural phenomenon, but have been suppressed for much of the past century. However, the fire regime may be shifting towards novel fire patterns due to changing climatic conditions. Effects of this evolving fire regime on native habitats and wildlife presence, especially resiliency and recovery, are not well understood.
We are investigating how a mega-fire affected presence of wildlife, in particular the Washington state-threatened western gray squirrels (Sciurus griseus, WGS) among other species in the North Cascades. The Methow Valley in WA experienced a record-breaking wildfire event in 2014, which disturbed ~50% of priority habitat for this population of WGS, as well as other wildlife species.
We conducted fieldwork in 2016 to answer: How resilient were wildlife populations, and how are they recovering post-fire? After the 2014 fires, we surveyed for WGS presence using hair samples. Camera traps were used to survey for other wildlife. Field habitat characteristic data were collected, and aerial photographs were analyzed for forest cover loss.
Between May-November 2016, WGS were present at over half of the plots (59%). There was a significantly less forest cover loss in areas where WGS were present than in areas where WGS were absent (t=2.14, p<0.04). From spatial analysis, the spatial extent of this WGS subpopulation was reduced from its pre-fire range, but has clearly survived despite a decline in range. From game camera photos collected throughout our plots, we saw much activity of other wildlife species.
One year after a large-scale fire we found that WGS and other wildlife species may be more resilient to disturbance in the form of large-scale fires than previously thought. However, this initial recovery of vegetation and wildlife may not continue due to a changing climate and potential future fires. Further monitoring of WGS and other wildlife following this fire will help elucidate long-term response to large-scale fires, and aid in management decisions.