Double crested cormorants

Double crested cormorants have seasonally nested along southbound Highway 101 near Sheffield Drive since 2013.


The Highway 101: Carpinteria to Santa Barbara project is primarily intended to address traffic congestion and safety on Highway 101, but project staff have also had to make a unique environmental consideration as they begin construction.

The project has employed measures to balance effective freeway construction with environmental protections specifically related to double crested cormorants, a protected bird species that has seasonally nested along southbound Highway 101 near Sheffield Drive since 2013.

The project leaders recently increased the frequency of air blasts due to the increased nesting activity of the cormorants with the goal to encourage nesting outside the construction area. Unfortunately, the increased frequency has had an unintended negative impact on the surrounding neighbors. In working with the project team biologists, and in collaboration with project partners, the project will be taking several steps.

First, they are shifting the focus of the habitat protection and nesting deterrence plan to rely more heavily on visual deterrents and human presence in the area. This is to significantly reduce or eliminate the use of air blasts to the benefit of project neighbors, while still being effective in encouraging cormorants to nest outside the construction zone. People can expect to see biologists monitoring the area daily, and see tree crews rotating visual deterrents. Climbers will also be switching out the use of Mylar flash tape for other visual deterrents, including owl silhouettes.

Project biologists will be on-site daily through April conducting monitoring activities and maintaining visual deterrents. Additional monitoring will continue throughout the nesting season, likely into September.

“Our priorities are to build this important project, protect the environment and be a good neighbor. This is a challenging situation with many variables to consider. We are refocusing our efforts to be a better neighbor and will continue to make sure we are effective. It is also important to keep in mind that if this plan doesn’t work, we could be looking at an additional year of construction and cost to taxpayers up to $10 million,” said Joe Erwin, Highway 101 Corridor Manager at Caltrans District 5.

Biologists have been monitoring the cormorants and their nest counts since 2013. As part of the highway improvements, a bird deterrent and protection plan was created by state and independent biologists focused on the cormorants. Avoidance and minimization measures were created as part of the 2014 Environmental Impact Report, supplemented with a Natural Environment Study in 2018, and approved by the California Department of Fish and Wildlife.

The multi-tiered plan began with monitoring, then removal of old nests outside of nesting season when birds were not present, visual deterrents (such as predator balloons), and auditory deterrents prior to and during nesting season. The goal is to protect the habitat area in the long-term, but temporarily encourage birds to find suitable nesting areas outside of the construction zone. This will reduce the potential for construction to impact nesting birds and their young.

The Highway 101: Carpinteria to Santa Barbara improvements represent a significant component of the overall solution to address traffic congestion by adding new peak-period carpool lanes and enhancements to improve freeway operations. For more information, visit

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