CROS: California Roadkill Observation System

Although an odd topic for CNPS, there are certainly flora-fauna tie-ins that makes this an adjacent, though offbeat, area of interest.  In short, “information about where wildlife vehicle collisions occur, what animals are involved, on what roads collisions are frequent, and other data can help inform policy, management, and financial investment in reducing roadkill.” (

Interestingly, there are zero to few reported observations for areas adjacent to our remaining wildlands in Palos Verdes and the Santa Monica Mountains, despite proximity to a large urban population of potential observers.   I think this is because we lack reporters.  If you are able, grab your phone and your nose and send some statistics their way!

California Roadkill Observation System reports as of 20230119

Email from CROS:

Hello CROS Observers

I hope you are all doing well and enjoying the start of summer. Roadkill reporting is going very well in California, thanks to many of you who regularly report roadkill. The new app  at is working well and is very easy to use. Basically take a smartphone pic of the roadkilled animal with your location turned on and upload to the system, with or without identification of the animal.

The data you are collecting is being actively used by Caltrans, CDFW, consultants, academics, and NGOs in scientific research and planning wildlife crossings. Secretary Crowfoot paid us a high compliment last year by calling CROS the “unofficial official roadkill database for California.” If you are not aware, we regularly report  our results in annual reports; here is the most recent: So, keep collecting those data, you are making a difference.

For our next steps, we have proposals out to a number of partner entities for funding (this will be our first funding ever) to support enhanced data collection, studies of the impacts of roadkill, and to make the data more accessible for planning wildlife crossings and fencing.

For those  who want to do a bit more, I have pasted a message from our friends at CDFW who want help with wildlife genetics, specifically collecting samples for genetic analysis.  I have pasted their message below and hope some of you can help out.

Thanks again for all you do for wildlife and please keep contributing your roadkill observations.

Fraser Shilling

CROS Lead and Director, Road Ecology Center (UC Davis)

on behalf of the CROS team

CDFW message below

Greetings Roadkill Observers!

Our team at the Wildlife Genetics Research Unit within the California Dept. of Fish & Wildlife (CDFW) requests your help.

We often rely on tissue samples from roadkill to improve the representation of understudied or rare species for archival in our Wildlife Tissue and DNA Biobank. These samples are frequently used for CDFW research but are also made available to our collaborators and other researchers throughout the country.

We are hoping you can help us recover roadkill samples when it is safe and feasible to do so. We are interested in a range of native California mammals, birds, reptiles, and amphibians. The process requires collecting a roughly dime-sized tissue sample and placing it in a small tube with desiccant beads to be stored at room temperature. We will provide sampling supplies.

While we hope to gain a diversity of species, we would like to highlight a current project as well. We are conducting the first range-wide genetic study of American badgers in California. We urgently need samples of badgers for this project, which will span the next 2 years.

Unsure of the species you’ve encountered? Send it to us anyway! We can perform genetic testing to determine the species and then archive the sample. Carcass seems old, dry, smelly, etc.? That’s ok too. These samples are still often useful to us despite decay and DNA degradation (if you are up for the job).

If the thought of collecting a small tissue sample from a decaying carcass in the name of science excites you, like it does us, you are in good company and we commend you. Here are the details of how to get involved:

  1. Email us at expressing your interest.
  2. We will respond by sending you volunteer paperwork to fill out and return. You will then be enrolled as an official CDFW volunteer (feel free to add to your resume!). This is critical, as the volunteer form will allow you to legally possess animal parts for contribution to our Wildlife Tissue and DNA Biobank work, including tissue of listed (e.g., endangered) species without needing to obtain an individual scientific collecting permit.
  3. Once your volunteer form is complete, we will email you tissue collection instructions and request your mailing address. We will send you a small collection kit, including PPE, via FedEx.
  4. Collect away! Of course, only when you are certain you can safely pull off the road and the carcass is in an accessible location.
  5. Store samples at room temperature in the collection tubes provided (as your car/trunk is too hot for more than a few hours). Every few months, you can ship us back the samples you’ve obtained. We pay for shipping.
  6. Email us anytime and let us know you found something rare/exciting!

Feel free to contact us with any questions you may have. We are appreciative of your support. These samples help advance our understanding of California wildlife for years to come.



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