Dividing Lines: Genetic Structure Splits Western Sandhill Crane Populations
New genetic evidence reveals deep divergence between coastal and interior Sandhill Crane populations along the Pacific Flyway, prompting calls for targeted conservation
Sandhill Cranes breeding along the Pacific coast of British Columbia and southeast Alaska are genetically distinct from their inland counterparts, a new study has confirmed. While all of these birds share the same migratory corridor, the Pacific Flyway, genetic analysis of over 200 individuals shows a clear divide between coastal and interior populations. The research, used microsatellite markers and mitochondrial DNA to reveal that cranes nesting west of the Coast Mountains are following their own evolutionary path.
The coastal birds, likely members of the subspecies Antigone canadensis rowani, differ significantly from interior populations in both their genetic makeup and ecology. Nesting in coastal bogs and foraging in intertidal zones, these cranes are isolated from inland birds not just by mountains, but by behaviour and habitat choice. As such, the authors argue they should be recognised as a distinct management unit, with conservation plans tailored to their unique needs and vulnerabilities.
Mountains, markers, and missed connections
The study analysed moulted feathers and blood samples from cranes in four regions: southwest Alaska, interior British Columbia, the BC coast, and Haida Gwaii. Microsatellite data showed strong genetic separation between the inland and coastal groups, even though some birds share wintering grounds in California. Mitochondrial DNA patterns told a similar story, with different haplogroups clustering by region and relatively few signs of gene flow between the coastal and interior groups.
Surprisingly, Haida Gwaii cranes were genetically more similar to those on the mainland coast than to interior birds, supporting the idea that coastal populations may have been isolated in glacial refugia during the last ice age. These findings suggest that the Coast Mountains, more than 500 km of rugged peaks and valleys, are not just a scenic backdrop but a powerful evolutionary barrier for Sandhill Cranes.
Citizen science meets cutting-edge genetics
The work relied heavily on non-invasive sampling by volunteers, who collected feathers from known breeding sites across BC. With help from online mapping tools and decades of citizen science records, the team was able to pinpoint important crane habitats and obtain high-quality samples with minimal disturbance.
“Cranes are highly site-faithful, returning to the same nesting areas year after year,” the authors note. “By mapping these breeding sites and combining them with genetic data, we can uncover long-standing population divisions that have major conservation implications.”
Implications for conservation and policy
While coastal cranes remain rare, with only small and scattered populations, they are currently managed under a one-size-fits-all approach in British Columbia. This contrasts with US states like California and Oregon, where subspecific conservation status leads to region-specific protections. The study’s authors argue that a similar approach is urgently needed north of the border to safeguard the unique genetic heritage of coastal cranes.
The threat is not just theoretical. As sea levels rise and coastal wetlands are altered by climate change and development, the specialised habitats of coastal cranes are under increasing pressure. Without recognition of their distinct status, these birds could quietly slip into decline.
Resilience in diversity
For a species whose haunting calls and graceful dances have long captured the imagination, the discovery of hidden genetic diversity adds a new dimension to the Sandhill Crane’s story. “Genetic structure isn’t just an academic detail,” says Joy. “It tells us how populations are evolving, how they’re responding to environmental change, and how best to protect them.”
In the case of the Pacific Flyway cranes, the message is clear: if we want to conserve the species, we need to understand - and respect - the divisions within it. Coastal cranes are more than just a scenic variant of a widespread bird. They are a genetically distinct population, shaped by history and geography, and increasingly, by human impact.
June 2025
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