Parrot Education Blog

Cattle have roamed California for centuries, arriving with the first Simage04panish missions in the early 1700s. Fast forward to present day and over 34 million acres of privately and publicly owned land — about a third of the entire state — are classified as rangelands. Grazing contributes significantly to California’s economy and managing these lands sustainably is an important challenge for the future. Now scientists are adopting drone technology to help measure and monitor grazing lands in novel ways.

Dr. Sean Hogan is the Drone Service Coordinator for the University of California, Division of Agriculture and Natural Resources (UC ANR), a statewide network of researchers and educators dedicated to the development and application of knowledge in agricultural, natural, and human resources. ANR has nine Research and Extension Centers (RECs) strategically positioned within the state, which together cover over 12,400 acres and represent the diversity of California’s agricultural and natural environments, including rangelands.

Sean Hogan





The advent of drone technology is extremely exciting to Hogan and his team because it provides a practical and affordable new way to collect on-demand high-resolution data about UC land interests.

“Data collection on rangelands is often tedious and time consuming and it’s a challenge to use these data for real time management decisions.” says Hogan. “If drones can be used to monitor rangelands more efficiently, it could help researchers and land managers better address time-sensitive questions and respond more quickly to changing environmental conditions.”

image01Parrot Sequoia page

Hogan and team are collecting drone imagery on rangelands using both high resolution color photos, as well as multispectral data from the Parrot Sequoia camera. Sequoia is the smallest and lightest multispectral sensor in its class, automatically capturing images across four discrete visible and non-visible spectral bands, as well as color (RGB) in a single flight.


Color infrared image (left) and normalized difference vegetation index (right) from a UAS image mosaic collected in the Bishop CA area. This image was acquired from an altitude of 100 feet above ground level, using Parrot Sequoia camera. The pixel resolution is approximately 1.45 inches, over approximately 10 acres. There are notable differences between grazed and ungrazed areas in both maps, providing crucial data to both the scientists and land managers.

Hogan uses photogrammetric software from Pix4D to stitch the photos into maps. These maps can then compared with ground measurements, such as clipping samples, collected from the experimental sites. Spectral characteristics of vegetation can then be compared to forage production/growth estimates to identify optimal times to stock cattle.  For example, periodic monitoring with drones could help ranchers to more accurately estimating the appropriate grazing density of a given area, which could financially benefit the ranchers and protect the environment  simultaneously.

Hogan has a long list of questions about drone data. “We want to know how precise and accurate can drone imagery be used to classify land cover.” he says,  “For example, can we accurately classify this imagery to differentiate noxious/invasive weeds, such as barbed goatgrass (Aegilops triuncialis), from more desirable forage for cattle? And how do we automate the process of change detection to flag problems quickly before they get out of hand?”

Another major issue on rangelands is cattle waste management.  Cows produce a lot of it. Hogan and teams are testing the extent to which drone imagery can be used to map the precise locations of cow dung deposits on the landscape in order to evaluate potential fecal coliform inputs into stream.  If the method works, drones could be used to help maintaining higher water quality in the streams and rivers that flow through grazing lands.

The ANR IGIS team is still in the early stage of testing the extent to which the drone technology can be used for rangeland applications. “The Sequoia camera has proven to be the most promising instrument that has so far been tested” says Hogan. “In the future we hope to expand the scale of its use from our initial <300 acres to areas as large as 5000 acres, to encompass even the largest of the UC ANR’s Research and Extension Centers.”

Despite early successes, more time out flying in the field is called for and the team will be hard at work in the coming months. Periodic reports on IGIS drone operations will be posted on their blog, as well as scientific journal articles that describe their findings in the future.

Next Post