Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
CARLSBAD FWO: Burrowing Owls and California Ground Squirrels Need Each Other
California-Nevada Offices , December 8, 2011
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Child recording burrowing owl banding data
Child recording burrowing owl banding data - Photo Credit: Janice Swaisgood
Owen and Luke captivated by the burrowing owl Clark Winchell is holding
Owen and Luke captivated by the burrowing owl Clark Winchell is holding - Photo Credit: Janice Swaisgood

By Clark Winchell and Stephanie Weagley, Carlsbad FWO

A three year conservation research project that began in 2011 is attempting to resolve uncertainties about the declining burrowing owl population in southern San Diego County. For the first time, researchers are establishing a ground squirrel translocation program to create self-sustaining burrowing owl habitat needed to help increase burrowing owl populations.

“Burrowing owls need burrows for shelter and burrow availability is a key limiting resource for burrowing owls in Southern California,” said Clark Winchell, Division Chief of the Carlsbad Fish & Wildlife Service’s Conservation Partnerships Program. “The California ground squirrel can help us create homes for the owls by digging burrows. This is in contrast to current management efforts that typically involve people creating and maintaining artificial burrows for owls.”

The purpose and benefits of this research project are multi-faceted. Not only will the research help establish a successful ground squirrel translocation program, it will also evaluate habitat utilization, burrow and prey availability, the role of ground squirrels as ecosystem engineers, and the impact of vegetation and site factors such as soils and topography. Additionally, it will test the effectiveness of habitat enhancement techniques used in supporting owl populations long-term.

California is an important wintering ground for burrowing owls and San Diego County supports both resident and migratory populations. But records indicate that burrowing owls previously inhabited a higher number of locations in the county than are presently occupied.

The California ground squirrel is a keystone species that helps engineer California grassland ecosystems and provides critical resources for burrowing owls. The re-establishment of this species is a crucial component of any recovery plan for burrowing owls and the larger ecosystem.

“Burrowing owls are subject to a complex array of interactions with predator and prey species, as well as with the numerous burrowing species they associate with,” said Winchell. “Populations can be limited by prey availability, predation, disease, habitat loss, or human activities such as road maintenance.”

This project was developed in consultation with multiple partners and includes the following land managers, scientists, and regulators: San Diego State University (SDSU), San Diego Zoo Institute for Conservation Research (ICR), California Department of Fish and Game, San Diego Association of Governments (SANDAG), and the U.S. Fish and Wildlife Service (Service). Funding for the project’s first year was paid for by the San Diego Foundation and SANDAG.

Specifically, the program was designed to combine the respective areas of expertise from all partner organizations while complimenting the San Diego County Multiple Species Conservation Program (MSCP). The MSCP is a comprehensive habitat conservation planning program whose purpose includes conserving the diversity and function of the ecosystems in southwestern San Diego County through habitat preservation and adaptive management.

Another benefit resulting from this project’s efforts included an opportunity for a few individuals to view burrowing owls up close and assist with the research.

It all started when Winchell needed help with the trapping efforts to capture burrowing owls. This task was necessary in order to track the owl's movement relative to where the ground squirrels created burrows.

“When I was contacted by the ICR to conduct this work at the Otay Mesa location, my lead time was limited,” said Winchell. “So, I simply sent an email to staff associated with the project and asked them to bring their families to help me check the traps at night and record data while fitting the owls with bands.”

Approximately 19 owls were captured and banded at the site. Children and their families were able to view the owls while they were being weighed, measured and banded, and participate in the research process by documenting scientific data. Burrowing owls serve as little ambassadors, providing an excellent opportunity for people to connect with nature.

The project is now completing its first year. During this time, the ICR and SDSU have examined what soil parameters are important to maintaining squirrel populations. This is a critical step to having self-sustaining populations of both squirrels and owls. Additionally, the knowledge gained may help lead to a reduction in management costs associated with the creation of artificial burrows.

Collaborative partnerships make it possible for the Service to fulfill its mission. It is the synergistic efforts of the individuals involved, along with the support of their respective organizations that make projects like this come to fruition.

Contact Info: Stephanie Weagley, 805-644-1766, stephanie_weagley@fws.gov
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