COS 94-6
What do pumas avoid when moving from the ocean’s edge to the Santa Cruz Mountains?
Habitat connectivity planning is complicated by the physical and habitat complexity – as well as the variety of land use types – found in California. In addition, habitat connectivity models are rarely tested against empirical data. Here we describe landscape permeability models derived from an estimated linear relationship between specific landscape features related to human land use (e.g. traffic volume, housing density) and species detection levels from empirical studies. We compare these model estimates with occurrence data for pumas (Puma concolor), a generalist predator commonly used as a focal species for connectivity analysis, in the Santa Cruz Mountains.
We used regression models derived from mesocarnivore and bird assemblage response to indices of the built environment as input to construct landscape permeability maps. For each map, we used as input a linear regression model derived using a single index of habitat development: distance to roads, median parcel size, or median patch size along with a corresponding relative abundance of species from empirical studies. We extrapolated each model across the study area using the permeability value and geographical position of all relevant landscape elements. We compared map predictions with the distribution of 81,237 location point data from 18 pumas.
Results/Conclusions
Our results show that pumas were observed to readily use moderately disturbed habitats, and rarely were detected in the most heavily disturbed areas. Specifically, 88.91% of the study area had a landscape permeability value for patches between 0.3 – 0.6 (11.1 – 21.21 ha). For roads, 88.50% of the study area had a landscape permeability value between 0.9 – 1.0. The distribution of puma location points was similar, with 90.17% of puma locations found at points with a patch permeability value between 0.3 – 0.6, and 95.96% of puma locations found at points with a road permeability value between 0.9 – 1.0.
This comparison of a more generic connectivity model estimate with animal field observations shows that while generic models can be useful for corridor designs in highly disturbed environments they may be less useful in moderately impacted semi-natural landscapes, where more detailed studies of species behavior may be required to delineate functional corridors. Mapping the level of landscape permeability that surrounds the built environment, as measured by distance to roads and housing density, offers a spatially explicit way to identify areas important wildlife movement. This approach provides a tool to help managers and land-use planners prioritize habitat corridors for biodiversity conservation across fragmented landscapes.