From Wyoming News
Across the nation there is an unseen shortage; in Wyoming, some of the state’s smallest long-distance travelers are not coming home.
Over the past 50 years, the population of birds as a whole across North America has dropped by nearly 3 billion birds, according to an estimate through 2019 research by Rosenberg et. al. This means that just over one in four birds in 1970 is no longer present across the landscape today.
Among this national decline, the burrowing owl population has dropped by about 55% during the same period, according to the North American Breeding Bird Survey. Out of the 254 species tracked by the survey, this places burrowing owls among the 30 fastest declining birds in North America.
This decline has contributed to Wyoming Game and Fish’s designation for the owl as a species of greatest conservation need.
However, the root of this rapid decline for burrowing owls is yet to be fully understood.
“I’m really hoping that we can learn from this larger study where the pinchpoints are in the annual cycle of burrowing owls,” explained Zach Wallace, statewide nongame bird biologist with Wyoming Game and Fish.
For a little more than seven years, the burrowing owl population and the full annual migration cycle of these owls have been tracked through collaborative research.
“It’s the biggest burrowing owl project that’s ever been done in the western U.S. so we have gotten a lot of good information from that project and it’s still ongoing,” Wallace said. “We’re awaiting the final results.”
Andrea Orabona, who formerly worked as a biologist for Wyoming Game and Fish, has been heavily involved in the project, alongside Courtney Conway and researchers with the University of Idaho.
Orabona said that reduction to burrowing owl habitat and lower populations of prairie dogs and grasshoppers may be critical factors to the decline of the owls.
In the Western United States, burrowing owls depend on prairie dogs to dig their burrows and grasshoppers for food. Orabona said that pesticide use within agriculture is likely a significant contributor to this reduction in grasshoppers.
The nature of the burrowing owl habitat may also mean that recreational use of these landscapes may play another role in the decline of the owls; however, research on human impact during recreational activities like hiking, biking and hunting is still minimal.
“Most of their distribution in Wyoming is in the low-lying basins of the state, so they’re on working lands, multiple-use lands, suburban areas, sage-brush steppe and prairie-type habitats. There are a lot of different activities going on on those lands, and so monitoring the species and conserving the species requires collaboration,” Wallace said.
For Orabona and other researchers, this collaboration heavily relies on data from little “backpacks” — tracking devices — that the project has attached to burrowing owls across over six U.S. states and two Canadian provinces.
“We look for burrows that have nesting activity,” Orabona explained, with researchers scouting out active burrows before trapping for the owls begins. “They are very efficient.”
Traps with food are placed, owls are tagged and equipped with tracking devices, the health and size of the birds is assessed and the birds are released. Orabona said that the whole process can take less than 15 minutes.
“Once captured, we band each owl with an individual, uniquely numbered band,” Orabona explained.
She said that before release, and as the birds begin to fly, researchers carefully assess if the placement of the devices interferes with flight or movement; any interference could not only skew the data of their study, but it could pose a significant risk to the safety of the bird.
These tracking devices follow the owls along their long-distance winter migration. Burrowing owls generally travel south to southwestern U.S. states and Mexico — distances that can reach anywhere from 500 to 2,000 miles.
The longest distance recorded for the migration of a burrowing owl was 4,500 miles.
“From an applied management perspective, we also get a lot of different kinds of information out of a study like this potentially. Some of those are basic information about how the species uses space: How big is its home range? How much space does it need?” Wallace reflected.
Wallace said this information can also be informative to when burrowing owls are active in Wyoming and more precise information about when they begin to migrate out of the state. For Wyoming Game and Fish, this can provide information as to when to prioritize conservation efforts.
“There’s no way that we could accomplish bird conservation without extensive collaboration,” Wallace said.
While research is still ongoing, Orabona said that she is hopeful that following the unique patterns of the owls migration will give more insight into where pressure points for threats for the bird’s population lie.
“It’s a way to synthesize what’s going on on the landscape,” she explained. “It’s not just one problem.”
Research efforts continue, with primary tracking efforts shifting north to Montana.
“With a study like this … they have the potential to answer all kinds of questions,” Wallace said.
