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CWHR Frequently Asked Questions and Software Troubleshooting

Is Version 9.0 an update of Version 8.2 or does it completely replace it?

It completely replaces it. We recommend you uninstall any previous version from your computer and go through a Version 9.0 installation.

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 modelled 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 only includes terrestrial vertebrates; however, it does include all regularly-occurring species which fit this category, including those accidentally or intentionally introduced. CNDDB only includes native special-status elements; but, unlike CWHR, it contains information on plants, fish, invertebrates and rare natural communities.

How do I cite CWHR?

Suggested citation for CWHR is:

California Department of Fish and Wildlife. California Interagency Wildlife Task Group. 2014. CWHR version 9.0 personal computer program. Sacramento, CA.

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.