National conservation area in Idaho supports top predator

Despite widespread declines in North American grassland bird populations over the last fifty years, a falcon species on a conservation area in Idaho appears to be holding strong. This is according to the new paper “Prairie Falcon (Falco mexicanus) Abundance in a National Conservation Area in Idaho Has Increased since the 1970s-1990s,” highlighted in the current issue of the Journal of Raptor Research. A team of collaborators from Boise State University and the U.S. Geological Survey conclude that Prairie Falcons nesting and foraging in the Morley Nelson Snake River Birds of Prey National Conservation Area (NCA) in Southwestern Idaho have increased in abundance and maintained nesting success over a 45-year period. This suggests efficacy of the NCA as a refuge for Prairie Falcons and offers a glimmer of relief for raptor conservationists.

Established as a Natural Area by the U.S Department of Interior in 1971, this area was first protected by U.S Congress as an NCA in 1993, partially because it hosts the highest density of nesting Prairie Falcons in the word. These are relatively large falcons with a range that extends from southern Canada to northern Mexico. They are often associated with grasslands, one of the most critically endangered habitat types on the continent.

The research team repeated Prairie Falcon surveys within stretches of canyon that were previously surveyed in the 1970s and 1990s. They assessed both abundance of falcon pairs as well as nesting success, defined by a pair raising one or more nestlings to at least 30 days of age. They used a cutting-edge survey approach called stratified random sampling, which can “reduce the amount of time, people, and money required to conduct extensive surveys,” says lead author Steve Alsup, offering a promising new tool for future raptor surveyors.

The team’s results were uplifting. Within this study area of the NCA, the Prairie Falcon population has increased in abundance in the last decades, and nesting success has held steady from 1974 through 2021. These results surprised Alsup, who says he “hopes that outdoor enthusiasts who recreate in the NCA will be excited to hear that at least one of the iconic raptor species the area was established to protect is doing well.”

Prairie Falcons are considered top predators, and their presence creates ripple effects across wildlife communities. Top predators are widely recognized as positive agents in bolstering overall ecosystem health they also serve as “bioindicators,” meaning they alert biologists to the overall health of the places in which they reside. Supporting their continued presence in the NCA is a priority that honors not only the falcons themselves, but the cherished landscape they depend upon.  

This study underscores the importance of long-term datasets in providing big picture overviews of changes in bird populations over time and also proves the effectiveness of the NCA as a conservation refuge for these falcons. However, the authors of the paper point out that the current stability of the population does not mean that Prairie Falcons are safe from environmental threats, and they advocate for continuation of long-term monitoring and a coordinated investigation into the ecological factors affecting the species across their range, not just within the NCA. “Without these survey results, researchers cannot detect population changes, and land managers lack crucial data to make well-informed management and land use decisions.” Alsup’s team has not yet located funding to continue falcon surveys but are on the search for continued support.

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Paper

Prairie Falcon (Falco mexicanus) Abundance in a National Conservation Area in Idaho Has Increased since the 1970s–1990s. 59(1): 1-13.
DOI: 10.3356

Notes to Editor:

1. The Journal of Raptor Research (JRR) is an international scientific journal dedicated entirely to the dissemination of information about birds of prey. Established in 1967, JRR has published peer-reviewed research on raptor ecology, behavior, life history, conservation, and techniques. JRR is available quarterly to members in electronic and paper format.

2. The Raptor Research Foundation (RRF) is the world’s largest professional society for raptor researchers and conservationists. Founded in 1966 as a non-profit organization, our primary goal is the accumulation and dissemination of scientific information about raptors. The Foundation organizes annual scientific conferences and provides competitive grants & awards for student researchers & conservationists. The Foundation also provides support & networking opportunities for students & early career raptor researchers.