With age comes knowledge for whooping cranes

By Dana Kobilinsky

A three-year old female whooping crane carries a freshwater mussel at the Necadah National Wildlife Refuge. This crane was raised at the Patuxent Wildlife Refuge. ©Ted Thousand

It’s not only people who can learn from their elders, but also whooping cranes that tend to follow older generations’ overwintering behaviors, according to new research.

As part of a study published in the journal Nature Communications, researchers studied the migratory and overwintering patterns of 175 federally endangered whooping cranes (Grus americana) from the species’ eastern migratory population. Most of the cranes were released as part of efforts led by the Whooping Crane Eastern Partnership (WCEP) — a collaboration between non-profit organizations, government agencies and individuals — to reintroduce a whooping crane population into the wild beginning in 2001.

In this population, some cranes migrate as far south as Florida while others get only as far as southern Indiana, according to Sarah Converse, a research ecologist with the USGS Patuxent Wildlife Research Center and second author of the study. “There are really extraordinary differences in terms of winter distribution between this population and the remnant population that winters on the Gulf Coast of Texas,” said Converse, who is a TWS member.

The researchers examined data collected from radio and satellite transmitters on birds that were released as part of WCEP’s reintroduction effort. Of these, some birds hatched at the Patuxent Wildlife Research Center and made their first southward migration behind an ultralight aircraft led by WCEP partner organization Operation Migration, while some were released in the summer to follow adult cranes south. A small portion of birds hatched in the wild from released parents.

After reviewing the tracking data collected from 2001 to 2015, the team found that the birds appear to follow their elders. “What we found is social transmission of knowledge,” she said. “Whooping cranes demonstrate culture — they learn from each other.” The researchers found that in the case of widespread shortstopping behavior in the population — where birds are progressively shortening their migration routes — older individuals appeared to establish new overwintering sites, which the younger birds then used.

In addition, there are some similarities in these sites: For instance, they tend to have more row crop agriculture and have warmed relatively more over the past 100 years. “The takeaway is that in responding to global climate change and land use change, the population is led by older individuals,” Converse said.

Converse says these findings might mean that since the culture of the reintroduced population is new and still developing, the birds don’t yet have ingrained migration patterns, and there’s more room for innovation and adaptation to global change.

Knowing where these birds tend to overwinter could also help determine where to release them and can help managers predict available habitat for them after their release. Still, the birds face additional challenges even after they’re released such as poor nesting success as well as a risk of getting shot.

“Most of the eastern U.S. hasn’t seen cranes in over a century, until just the last 15 years,” she said. “We need an increase in education and understanding of the importance of these birds and the conservation of the species.”

Dana KobilinskyDana Kobilinsky is a science writer at The Wildlife Society. Contact her at dkobilinsky@wildlife.org with any questions or comments about her article. You can follow her on Twitter at @DanaKobi.

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