This summer, I had the opportunity to assist with the San Diego Zoo Institute for Conservation Research’s western burrowing owl banding effort in San Diego County. A team of researchers worked this spring and summer to trap, band, and observe burrowing owls in South County to monitor the population in the area (see My Summer Staycation: Burrowing into Owl City. The bands serve as unique identifiers and allow us to track individual birds over the course of their lives, monitoring such things as survivorship, breeding success, and home range. For the previous two years, I have been researching California ground squirrel and burrowing owl habitat requirements in San Diego County grasslands, so it was very exciting to finally participate in some work with the actual owls.
On a summer afternoon in late June, we arrived at our site. We pulled off the main road to a place where we could observe the owls’ behavior without disturbing them. We set up our scope and saw them: two adults hanging out by a California ground squirrel burrow they had chosen as their nesting site earlier in the year. The chicks were hidden inside the burrow.
It was especially meaningful for me to help out with trapping and banding the chicks at this site, as I had visited this location earlier in the year to conduct ground squirrel surveys and gather habitat data and soil samples. On our last day of ground squirrel surveys here in April, we had seen a male burrowing owl using one of the squirrel burrows. I wondered at this moment if this was that same bird I had seen months before, now paired with a female and with chicks of his own.
As we approached the nesting burrow, both adults flew away, in an attempt to distract us from their chicks, and continued to keep a close watch on what we were doing. We used burlap sacks to block all but the main burrow entrance at the nest, and then placed a one-way door trap at that entrance. While the chicks could exit the burrow and enter the trap, they would be unable to leave the trap once inside.
We returned a short time later to find three burrowing owl chicks inside the trap—success! Carefully removing the chicks from the trap, we placed them in a pet carrier so they would be more comfortable as they waited to be banded. During the banding process, we took morphological measurements such as weight, wing length, bill length, and tarsus height and length. A small blood sample was also taken from the birds for genetic analysis. We moved quickly so the chicks could be returned to their burrow as soon as possible.
Upon their release, the chicks scurried back into their burrow with their new bands on. I hope they will survive the rest of the non-breeding season, and we’ll see them again in the spring—maybe with chicks of their very own!
Susanne Marczak is a research technician with the San Diego Zoo Institute for Conservation Research. Read her previous post, Citizen Science: Engaging People in Conservation Research.