By Kyrmyzy Turebayeva
Along the shores of the Great Lakes, the piping plover (Charadrius melodus) remains one of North America’s rarest and most vulnerable birds.
Predation is one of the challenges facing these migratory shorebirds.
Among the predators are merlins (Falco columbarius), small but fast falcons that may use areas near piping plover nesting sites.
To determine whether temporarily moving merlins could help protect this endangered species, researchers captured the birds of prey and relocated them away from piping plover nesting areas.
A new study in the Journal of Wildlife Management found that about 42% of translocated merlins did not return to their original territories during the same breeding season.
Researchers say the findings suggest that temporary merlin translocation could become a promising non-lethal management tool for reducing predation pressure on Great Lakes piping plovers.
“Great Lakes piping plovers were listed under the U.S. Endangered Species Act in 1984, when there were only 13 breeding pairs in the region. Today, according to the Great Lakes Piping Plover Recovery Program, there are about 95 breeding pairs, which is the highest number recorded in more than four decades,” said Fernando López, a former postdoctoral fellow with the Migratory Bird Center at the Smithsonian’s National Zoo and Conservation Biology Institute and a co-author of the study, via email.
However, conservation experts emphasize that the population remains very small, meaning that the loss of even a few adult birds, eggs or chicks can slow the species’s recovery.
Some individual merlins may overlap with piping plover breeding areas during the nesting season and represent a potential risk to adult birds and chicks.
“Merlins are far from the only threat facing Great Lakes piping plovers. The species also faces habitat loss and degradation, human disturbance and even unleashed pets on beaches. Because the population remains very small, unpredictable or stochastic events, such as severe storms or disease outbreaks, can have a significant impact on recovery,” López said.
Despite multiple threats, researchers say predation remains one factor limiting the recovery of the piping plover population.
Population models suggest that reducing predation on adults and chicks could significantly lower the risk of extinction.
That is why researchers evaluated whether temporary merlin translocation could serve as an additional conservation tool.
Conducting the study required extensive fieldwork along the Great Lakes shoreline.
According to López, the research team spent significant time preparing applications for permits from government agencies and landowners, as well as driving long distances, hiking field sites and searching for territorial merlins across thousands of miles of shoreline.
During two breeding seasons, researchers detected 199 merlins, attempted to capture 85 and successfully captured 33.
Most were captured using mist nets and robotic owl decoys.
After capture, the birds were banded and fitted with lightweight GPS transmitters that allowed researchers to track their movements after release.
Following capture and processing, merlins were placed in specialized transport carriers and moved between 101 to 404 kilometers (about 63 to 251 miles) away to selected release sites.
“These distances partly reflected practical limitations of the project. Our permits allowed us to capture and release birds only within Michigan. During transport, we regularly monitored the condition of the merlins, released them within 24 hours of capture, and remained at the release site to make sure the birds resumed normal behavior,” López explained.
Release sites were selected to provide suitable habitat while avoiding piping plover nesting areas, airports and territories already occupied by other merlins.
Researchers emphasized that the goal was not to eliminate a native predator, but to reduce conflict between merlins and an endangered species.
After translocation, researchers tracked the birds’ movements using GPS transmitters.
“Any capture and translocation involves some temporary stress for birds, and we worked to minimize this impact. We followed animal welfare protocols and monitored the condition of merlins during transport and after release. GPS data showed that birds continued moving normally after translocation,” López said.
The study found that about 42% of translocated merlins did not return to the areas where they were captured during the same breeding season.
Further analysis showed that the likelihood of return wasn’t simply a factor of the distance birds were moved: Sex, age and direction of translocation had a stronger influence on outcomes.
For example, older birds and males were more likely to return, likely because they had stronger attachment to established territories.
Researchers also found that not all merlins were equally connected to piping plover nesting areas: GPS tracking showed that about 25% demonstrated a clear preference for Great Lakes shoreline habitats.
According to researchers, this suggests that potential risk to piping plovers is not associated with all merlins, but rather with individual birds that repeatedly appear near nesting areas.
“Our results suggest that management may be more effective if it focuses not on all merlins, but on individual birds that repeatedly use shoreline areas near piping plover breeding sites and may represent a greater potential risk,” López said.
López emphasized that merlin translocation is not a universal solution and cannot replace other conservation measures.
However, the approach could become part of a broader recovery strategy for Great Lakes piping plovers that includes habitat protection, reducing human disturbance and addressing other threats.