Wildlife-vehicle collisions

US 101 in Northern California adopts tech system to offset wildlife-vehicle collisions

By Silas Valentino

A short stretch of Highway 101 along the North Coast is particularly plagued by wildlife-vehicle collisions, which have exacerbated an ongoing human-elk conflict in Humboldt County.

In 2023 so far, three Roosevelt elk have been killed in collisions with vehicles along the stretch of Highway 101 south of Orick, and five were killed in the previous year, although Caltrans said the figures are likely underestimating their true numbers.  

Roosevelt elk, the largest of the three subspecies of elk native to California, can weigh more than 1,000 pounds. They are also not afraid of humans and have been known to charge at cars. 

A multiagency effort to help prevent wildlife-vehicle collisions, expected to go live in 2024, requires placing transmitting collars on elk, which will activate signage to warn drivers that an elk is nearby. Researchers are targeting female elk, called cows, for the collars because they are philopatric and remain in one area — unlike male elk, or bulls, which roam when they’re not in the rutting season among their harems. 

“Everyone has seen these signs like ‘deer crossing,’ but you ignore them. If a sign is flashing that there is a hazard and threat on the road, I think that’s going to work,” said Micaela Szykman Gunther, a professor at Cal Poly Humboldt Wildlife Department who is collaborating on the project. 

Roosevelt elk, the largest of the three subspecies of elk native to California, can weigh more than 1,000 pounds. They are also not afraid of humans and have been known to charge at cars. 

Roosevelt elk, the largest of the three subspecies of elk native to California, can weigh more than 1,000 pounds. They are also not afraid of humans and have been known to charge at cars. 

Courtesy of Caltrans

Researchers at Cal Poly Humboldt partnered with the California Department of Fish and Wildlife and Caltrans to adopt the electronic detection system. Caltrans told SFGATE if the system is successful, it could serve as a model for reducing wildlife-vehicle collisions across the state. 

The electronic detection system is funded by Caltrans’ Division of Research, Innovation and System Information, which provided a $500,000 grant to cover the installation of transceiver posts, changeable message signs, unique signage, lights and solar equipment to support the system. Caltrans estimates that the projects could eventually run up to $900,000.

The roadside sign for motorists is in the design phase and is expected to display a silhouette of an elk with a clear message that an elk is approaching the highway.

The detection system works by installing 20 posts with antennas alongside Highway 101 that are spaced 300 feet apart. When an elk comes within 150 feet of a transceiver, it sends a signal down the line to activate a sign to warn drivers to slow down and pay attention. 

Caltrans ranked the corridor of Highway 101 near Orick and alongside Stone Lagoon as the “foremost location” for wildlife-vehicle collisions in coastal Humboldt and Del Norte counties.