Capturing and Banding Burrowing Owls on Antelope Island
Staff members from Tracy Aviary Aviculture and Bird Programs departments recently participated in a conservation fieldwork study focusing on the presence and prevalence of nesting populations of burrowing owls (Athene cunicularia) on Antelope Island State Park. This locally conducted research on the burrowing owl, now considered a Species of National Conservation Concern, will contribute to a larger international effort to determine causes behind specific population declines within the western range of this species. The ultimate goal is to implement management strategies to reverse population decline. But the study is also looking to provide insight into the distribution of the owl’s wintering grounds and migratory routes, which are relatively unknown and considered vital to the preservation of the species.
Led by biologist Boyd White, with help from the Department of Natural Resources, our team embarked on an evening of trapping. Nest sites, which are unoccupied badger holes, were determined “active” before our arrival by another group of volunteers based on visual sighting of one or more birds around the burrow. A two-way trap made of burlap and wire mesh was carried through the sagebrush landscape to each nest site and left for approximately one hour. Depending on the location, a bal-chatri trap was placed near the entrance of some nests in an attempt to trap an adult. Casting material (the undigested bones / fur that an owl regurgitates) was seen at the entrance to some of these burrows, which are often a good indicator of an owl’s presence and the likelihood of successfully trapping at the site.
Four of the eight traps set yielded results, with each trap containing 2-6 juvenile owls. Each juvenile owl was banded, weighed, and aged based on plumage, and specifically using the number of tail feather bands (more bands means an older bird). No adult birds were trapped, and most of the juveniles caught were unbanded and in the 28+ days age range. After data was obtained, the juveniles were returned to the burrow.
Aviculture Intern Melissa King-Smith (center) restraining juvenile burrowing owl for banding
For all parties involved, this opportunity to work with a native species was a tremendously fulfilling professional experience. Viewing the natural behavior and environment of this species has inspired enclosure modification for our own Tracy Aviary burrowing owl pair, provided our Education/Aviculture interns with the exploration of an alternate career path in conservation, and given our on-site interpretive educators a meaningful local connection to share with our visitors.