New Collaborative Research to Support Kestrel Conservation

Postdoctoral researcher Kristin Davis and a team of researchers and land managers published a pair of scientific papers that used advanced population modeling and decision analysis to address a long-time ecological mystery for the American kestrel (Falco sparverius), and a collaborative process to chart a path forward. 

The researchers and land managers are affiliated with the U.S. Fish and Wildlife Service (USFWS), U.S. Geological Survey (USGS), one Tribal and multiple state governments, multiple universities, and NGOs.

“It was really inspiring to work on a common but declining species like the American kestrel that has such a large, active, and committed group of researchers and land managers across the United States trying to support it. Collaborative efforts that tie insights from population modeling to local management practices and information gaps are essential for supporting wildlife species, particularly as these species face compounding pressures from modern environmental change.” – Kristin Davis

Key Concepts

• Integrated population models allow for different data sources to be combined into a single model to describe population dynamics for a species. 
• Constructed Value of Information (CVol) is a tool for rapidly assessing whether the benefit of gathering more information–in order to reduce uncertainty–outweighs the cost of acting in the face of uncertainty. 

A driver of population decline revealed

The American kestrel is the smallest and most common falcon in North America, yet populations of the species have been declining since the 1960s for unknown reasons, despite extensive research and conservation interventions.

In a paper led by Paige Howell of the USFWS National Raptor Program recently published in Ecosphere, the research team and a national group of species experts and quantitative ecologists used an integrated population model to quantify kestrel population dynamics at the scale of North America. The model was built using over 30 years of publicly available data from the U.S. Geological Survey Bird Banding Laboratory and North American Breeding Bird Survey, and over 10,000 nesting records generously shared by individual kestrel researchers, the Peregrine Fund's American Kestrel Partnership, and the Cornell Lab of Ornithology’s NestWatch Program.

Key Concepts

• This modeling effort is the first to report a long-term negative trend in juvenile summer survival. From 1986 – 2019, the survival of juvenile birds and adult males in the summer (i.e., the breeding season) declined over time.
• While the survival of juvenile birds during the winter increased, the increase was not enough to offset declines in summer survival, and annual survival rates of juvenile birds declined over the time series.

“Past research on kestrel population dynamics revealed that although vital rates were not sufficient to maintain a stable population, it was unclear which vital rate or rates were deficient. By stepping back and taking a look at the continental scale using an integrated population model, we were able to identify declining survival, particularly during summer, as the likely driver of the decline. This finding also serves to narrow the list of possible environmental factors that have caused kestrel numbers to drop.” – Brian Millsap, Senior Research Scientist, New Mexico State University and coauthor of the publication in Ecosphere.

 

Management-relevant research priorities collaboratively identified

In tandem with the population modeling effort, Kristin Davis led a paper recently published in Conservation Biology that describes a collaborative process to identify and prioritize management-relevant research needs for the species. Kristin and the research team convened a national group of land managers and species experts, including some of the researchers working on the integrated population model, to collaboratively develop hypotheses about kestrel population declines. The group used CVoI to score each hypothesis’s learning potential, relevance to management, and feasibility to study. Kristin conducted this research as part of her previous postdoctoral position in the New Mexico Cooperative Fish and Wildlife Research Unit at New Mexico State University.

Key Findings

• The nest cavity type hypothesis scored highest for learning potential and relevance to management. Kestrels are cavity nesters, and nest boxes are a common management tool for supplementing habitat for kestrels. The vast majority of kestrel nesting data comes from these artificial nest sites because natural tree cavities are difficult to monitor. Determining if nest boxes provide a demographic (dis)advantage over natural cavity nests would have broad implications for their continued use as a management tool.
• The road mortality hypothesis scored highest for feasibility to study. Because publicly available datasets exist in the US for roads and for bird mortality (e.g., from the USGS Bird Banding Laboratory), it could be possible to evaluate how road density or road proximity to nesting areas influences kestrel populations and to relocate nest boxes to areas with fewer roads to benefit kestrel populations if a negative effect were determined.

“This study highlights the potential for decision science to help managers focus research to directly inform management decisions. By identifying the biggest knowledge gaps and the questions that are easiest to answer, this type of approach can help managers consider and ultimately direct resources toward actions that will have the greatest impact on keeping kestrel or other wildlife populations healthy.” – Jennifer Herner-Thogmartin, Zone Biologist, US Fish and Wildlife Service and coauthor of the publication in Conservation Biology.

“Natural resource managers have more tools and technology at their disposal than ever before to address information gaps, which can make it difficult to know where to start. Constructed value of information shows enormous potential to help managers efficiently and collaboratively identify the most pressing uncertainties that hinder decision making.” – Abby Lawson, Assistant Unit Leader, USGS New Mexico Cooperative Fish and Wildlife Research Unit, New Mexico State University and coauthor on both publications.

The kestrel project was funded by the USGS and USFWS Science Support Partnership program.