CWHR Frequently Asked Questions and Software Troubleshooting

Does the CWHR web application replace the CWHR program I installed on my own computer?

Previously downloaded software versions of CWHR (versions 9.x and preceding) which require user installation on the client side, will continue to function on Windows 10, but will no longer be supported and will be drawing from static information that has not been updated since 2019. We highly recommend discontinuing use of CWHR v.9 or below, and transitioning to the online CWHR v.10 web application. For certain uses that require the most recent data, CWHR v.9 or below will not be accepted.

What is the difference between the California Wildlife Habitat Relationships System (CWHR) and the California Natural Diversity Database (CNDDB/RareFind)?

CWHR is a predictive model — it lists species predicted to occur in a given location under certain habitat conditions. It also predicts the suitability of those conditions for reproduction, cover, and feeding for each modeled species. CNDDB is a database of positive sightings — it tracks detailed information on the locations where the state's rarest species and natural communities have been identified.

CWHR contains information on terrestrial vertebrates only. This includes all regularly-occurring species, as well as those accidentally or intentionally introduced. In contrast, CNDDB encompasses a wider range of taxa, including terrestrial vertebrates as well as plants, fish, invertebrates and rare natural communities. However, CNDDB principally tracks only those elements with special status.

How do I cite CWHR?

Suggested citation for CWHR is:

California Department of Fish and Wildlife, Biogegraphic Data Branch, 2021. California Wildlife Habitat Relationship System, Version 10.x.x. Sacramento, CA. access date: use current date

Can I place a weight greater than 100 on a 2 condition Weighted Habitat Value Comparison Report?

No. The values were designed to represent a percentage of the total (100% or 100) project area. For example, if your study area is covered by 1/4 of a habitat type than the weight for that habitat would be 25% or 25; 1/2 would be 50% or 50, etc.

I see special status codes (e.g., Federal Endangered) on my report for species that I know do not have special status.

Special status is documented at the subspecies level but reported at the species level. For example, the common garter snake (Thamnophis sirtalis) is coded as "California Endangered" on reports because the San Francisco garter snake (Thamnophis sirtalis tetrataenia) is listed this way. One way to find out which subspecies is responsible for the special status code on a report is to check the "Activity/Status" in the "Species Information" window accessible from the main menu. For some subspecies, range maps are available so you can check if your species occurs in your study area; if one exists for a species, a button on the window will become accessible.

How do I report what I think is a data error in a CWHR model prediction?

You can email us at to identify the problem you see. We need to know your query parameters so we can duplicate your query. For example, what locations, habitats, seasons, etc. did you select? Did you exclude any habitat elements? We also need to know the source of your data (e.g., field observation, published validation study). We then evaluate and document the proposed error. If it results in a change to a data table, the source of the change will be documented and the change will become part of an update.