Inside Prairie Falcon Research: Zoe Bonerbo’s Work in the NCA
By Annabel Christiansen
I recently had the opportunity to sit down with Zoe Bonerbo, a raptor researcher working towards her Master of Science in Raptor Biology at Boise State University, to learn more about the prairie falcon research she is conducting in the NCA.
Prairie falcons (Falco mexicanus) have a special relationship with the NCA - it has the highest breeding density globally, with 200-250 breeding pairs calling the NCA home each spring. The prairie falcon population is relatively strong in the NCA, which is unfortunately not a universal trend. Despite widespread declines of other North American grassland bird species across the US, the prairie falcon population in the NCA seems to be thriving, at least for the moment. This makes the NCA the perfect place for research that will create a better understanding of these elusive birds.
Why the NCA is Key for Prairie Falcon Studies
Zoe Bonerbo is a raptor biologist and researcher pursuing a Masters of Science in Raptor Biology at Boise State University. Her research questions center around the relationships between foraging ecology and nesting success of prairie falcons in the NCA. Her days often involve long drives to nest sites, locating and monitoring the scrapes (nests), making visual observations, and performing strenuous and difficult climbs to install or retrieve nest cameras.
It isn’t easy work, but it is important for both prairie falcons and other species that share their habitat. Apex predators, like prairie falcons, can act as an indicator species. If a decline in the population of an indicator species is detected, it gives researchers a good indication that some environmental stressor may be influencing a species or several species that the falcons depend on throughout the year.
Studying Prairie Falcon Nesting and Foraging Behavior
An increasing or decreasing prairie falcon population can give us valuable insights into other food webs and ecological systems taking place in the NCA, including Snake River Plains ground squirrels which are connected to prairie falcons through predator-prey dynamics.
Zoe wants to learn more about behavioral traits of prairie falcons that can affect their foraging behavior and nesting productivity (number of young produced). She utilizes nest camera footage and visual observation to assess prey selection and productivity, and GPS transmitter data to track adult survival and movement patterns.
Understanding Nest Failures and Predation Risks
Of the nests that Zoe monitored through nest camera footage this past breeding season, roughly half of them failed – meaning no young fledged from the nest. The reasoning behind a majority of the nest failures still remains unknown - many instances of failure occurred during the fledging stage, when the nestlings were large enough to explore the cliff ledges around the nest and were out of sight of the camera. However, based on nest camera evidence, predation seems to be a notable factor affecting the success of prairie falcon nests.
Because prairie falcons prefer to nest on cliff ledges and canyon walls, their nests can be exposed and vulnerable to various predators, such as coyotes, foxes, golden eagles, great horned owls, and even ravens. Zoe’s team are the first to install cameras at prairie falcon nests, and this new, innovative monitoring technique provided valuable documentation of predation at multiple nests.
The Importance of Prairie Falcon RESEARCH in the NCA
The nest failures show us that there is still much to learn about prairie falcon breeding behavior - researchers like Zoe are working hard to address these research gaps and increase our knowledge and understanding of these incredible birds, and how we can help them continue to find success in the NCA.