The Southern Sierra Nevada Fisher Conservation Strategy (SSNFCS; Spencer et al. 2016) was completed during a multi-year drought that substantially affected the pre-drought fisher habitat conditions that the strategy was based on.
This gallery presents a new, post-drought Fisher Reproductive Habitat Model to replace the former fisher denning model. Included here are the model outputs and a report documenting them.
All models are abstractions of reality that are created for particular purposes and should be used with caution. The fisher reproductive habitat model and maps presented here provide an approximate, landscape-scale representation of those areas of the southern Sierra Nevada considered most likely to support fisher mothers and young during that sensitive portion of the reproductive cycle when kits remain with, and are likely dependent on, their mothers. Sustaining and possibly increasing the value and distribution of fisher reproductive habitat is important to sustain and recover this Endangered fisher population. Maps depicting the distribution of modeled moderate and high-value reproductive habitat are meant to focus management attention, not to prescribe specific management actions or specific management areas. Female fishers are known to establish dens and reproduce outside of modeled moderate-high value areas, and these maps should not be used to conclude absence of reproductifve habitat, dens, or fishers outside of thresholded High and Moderate habitats. We recommend managers use the thresholded version (High and Moderate reproductive habitat value) for project planning purposes, in concert with additional, local or fine-scale information where available, and field reconnaissance where possible.
This new reproductive habitat model differs from the fisher denning model in the following ways:
- Because den locality data was limited in scope, and has become even more limited since 2016, this model was built using a combination of observations indicative of habitat use by female fishers for denning and raising young. In addition to actual den locations (R. Green, USFS Pacific Southwest Research Station, unpublished data), it uses detections of fisher families, young, or adult females during the denning season (from June, when seasonal sampling begins, through August, when kits gain independence) as also representing reproductive habitat use (J. Tucker, USFS Region 5, unpublished data).
- Because the fisher data include den locations as well as those used by mothers and young moving about their home ranges, this model is more representative of fisher “reproductive habitat” (i.e., denning plus rearing habitat) than denning habitat. However, depending on scale, these habitat classes (denning and reproductive) are expected to be highly coincident or perhaps even the same.
- Because this combination of fisher locality data is broader in geographic distribution than the telemetry-obtained den localities used to create the 2012 denning model, the results can be extrapolated with more confidence over a broader geographic area, including most of the fisher conservation strategy area.