Arizona Wildlife Conservation Strategy

Species Distribution Modeling

Following the ranking of SGCN, we created habitat suitability models for all Tier 1 and Tier 2 SGCN to represent the potential distribution for an individual species. Focus was given to SGCN species, however models for additional species may be developed and made available as time allows. While we attempted to establish a consistent modeling approach for most species, alternative approaches were needed for some species. The quantity and quality of occurrence data, known distribution/range of a species, and availability of existing models created a scenario where different methods were optimal for different species. Prior to developing/updating models, AZGFD species experts completed a review of the current SGCN species distribution models developed over the past 10 years. The SGCN were prioritized based on availability and/or accuracy of existing models with the goal of modeling all Tier 1 and Tier 2 SGCN.

For most species, modeling methods included Random Forest (RF) and basic envelope niche models. For fish species, we used simple distribution maps that correspond with Watershed Management Plans (WMPs), which identify priority species for each management unit. 

Random Forest is a commonly used machine learning ensemble method for estimating species distributions, and our preferred approach for species for which habitat had not yet been modeled and for those species whose habitat models needed improvement. In addition to being intuitive and performing well with a small set of known locations, a major advantage of using this approach is that the RF model script includes code to generate a comprehensive report capturing metadata and assessing the quality of key model components, providing a tool to identify model limitations and to indicate appropriate use. The result is a transparent process and reproducible model.

Where existing envelope niche models were deemed accurate by AZGFD species experts, these models were simply updated and metadata were recorded. Inputs for envelope niche models included the following base layers:

  • Vegetation Associations: a modified version of USGS’s SWReGAP land cover layer or, in certain cases, LANDFIRE National Vegetation Classification layer

  • Elevation and Slope Associations: a 30m digital elevation model (DEM) for Arizona

  • Watershed Associations: HUC boundaries at the 10-digit level created by the Natural Resources Conservation Service (NRCS)

  • Species Occurrence Data: used to identify watersheds associations for individual SGCN species

Potential distributions for fish species are mapped using basic GIS processing (ArcGIS Pro v. 2.8.0) to relate species to streams, reaches, and water bodies in each management unit as established in AZGFD WMPs. These WMPs identify goals, desired outcomes, and priority species that are managed within each management unit. The WMPs represent a thorough evaluation and comprehensive management framework for ensuring conservation and protection of native fishes as well as abundant sportfishing opportunities in Arizona.

Filling the Data Gaps

Increasing our state’s knowledge of wildlife resources and requirements will improve our ability to take appropriate actions to protect and conserve wildlife and their habitats for future generations. Continued focused research is needed to better understand fish and wildlife species responses to conservation challenges including climate change. In addition, some data necessary to evaluate the vulnerability of the Tier 3 species are missing. Filling those data gaps will be a focus moving forward.

Currently, AZGFD is developing a Wildlife Data Warehouse (WDW), a centralized data repository for all of the wildlife data collected by AZGFD. The WDW will allow mining of data across projects and over time. Data will be pulled, in near real time, into a data viewer — the Conservation Analysis Tool (CAT) — allowing for spatial analyses to occur regularly, as appropriate, depending on the type of data and how it was collected. Changes on the landscape will be tracked through the CAT and can be used to reassess species’ status as needed and adjust information regarding the Conservation Opportunity Areas (COAs). The web-based AWCS will allow AZGFD to update existing information on species, threats, and landscapes, as it becomes available, and to share those data publicly through the web AWCS website. See Appendix D: Species of Greatest Conservation Need with Vulnerability Scores for a full list of Tier 3 SGCN by taxonomic group.