Burrowing into Conservation
Charismatic, cute, adorable, small and wonderful - these are just a few ways to describe burrowing owls. After all, burrowing owls are not your typical owl. They are one of the smallest owls in North America, use burrows created by digging mammals, such as ground squirrels, for nesting, and are active during the day (unlike most owls). Unfortunately, western burrowing owl populations are on the decline.
One of the main causes for their decline is habitat loss. Grasslands, particularly in California, are disappearing due to development and other human uses. Plus, most of the grass and forb lands that remain are now dominated by exotic species. Because of this, it is not surprising that a number of grassland species, including burrowing owls, are now of conservation concern. Another prominent grassland species, the California ground squirrel, is abundant and common, but generally undervalued even though it is an integral component of this ecosystem and has a strong positive interaction with burrowing owls.
In 2011, the Institute for Conservation Research (ICR) and the Institute for Ecological Modeling and Management (IEMM) launched a multi-year study to assist in the recovery of western burrowing owls and their grassland ecosystem in San Diego County. One of the main objectives was to restore ecological function to the grassland ecosystem by re-establishing ground squirrels and ultimately burrowing owls. Our aim is to create suitable burrowing owl habitat through the ecosystem engineering activity of ground squirrels that is self-sustaining and less reliant on repeated human intervention.
In addition to our efforts to re-establish ground squirrels and create self-sustaining burrowing owl habitat, we have begun monitoring burrowing owl nesting ecology. Currently, we are monitoring both natural and artificial burrow sites in southern San Diego County. To assist with monitoring, we are capturing and color banding individuals so that we can recognize individual birds from known nest sites.
Each individual captured is banded, measured, weighed, and examined for external signs of parasites and disease. We are also collecting genetic samples for future analyses of this dwindling population. Re-sighting these banded birds will be instrumental to our understanding of their spatial movements within San Diego County, of which we know virtually nothing.
In addition, the return of banded young in future years will provide insights into recruitment, dispersal, and settlement patterns.
Using camera traps, we are also able to document parental care, reproductive success, and nest predation. Some of the photos obtained from this effort have been nothing short of amazing! Burrowing owl behavior, predation, and other events that would have normally gone unnoticed are now being revealed through these photos. Capturing these photos is relatively easy, but photo review and data management for tens of thousands of photos per nest presents a real challenge. Volunteers are needed to help in this effort.
We are also trying to figure out why ground squirrels and burrowing owls are found in some places and not others. To better understand this, we are conducting habitat surveys to determine the key habitat characteristics associated with each of these species. Results from these surveys will help us identify critical habitat in San Diego County for burrowing owl management and recovery.
Using this combined approach, we hope to help build a conservation program that will help restore the natural grassland ecosystem and aid in the recovery of burrowing owls. While this research requires lots of hard work and long (often dirty and sweaty) days, the rewards make the effort all worth it.
If you are interested in contributing to this project, please donate to the Wildlife Conservancy or sign up to volunteer with our Volunteer Department.
Lisa A. Nordstrom, Ph.D.
Scientist, Applied Animal Ecology