Terns face higher risk of population declines when they fly south

As you might image from its name, the Common Tern is indeed one of the most predominant species of tern in North America, but the birds’ breeding colonies appear to be suffering despite conservation efforts.

A new study has found that in order to fully protect a migrating species such as the Common Tern, it’s crucial to find out where the bird spends its time during migration.

In the case of the term, the problem behind its decline can be found outside of the species’ seasonal nesting lakes.

The study was conducted by researchers from the University of Minnesota and published in the journal The Auk: Ornithological Advances.

Researchers attached geolocators to 106 terns from breeding colonies in Manitoba, Ontario, Minnesota, New York, and Wisconsin. The geolocators recorded the birds’ locations over time as they migrated during the winters.

The birds returned to their nesting lakes and breeding grounds and the researchers were only able to retrieve data from 46 of the original 106 terns that were first captured for the study.

The records from the geolocators showed previously unknown migratory staging areas inland of the United States and along the Gulf of Mexico.

This was surprising for the researchers, as previously it was assumed that Common Terns typically headed for the Atlantic Coast first and then continued south.

Instead, they discovered that most of the terns, no matter the colony they first came from, ended up in Peru.

Considering Peru’s susceptibility to climate change, the terns face an increased risk of severe storms, food shortages, and rising sea levels during the winter.

Any conservation efforts should then take this into account and focus on management and protection policies in Peru first and foremost, in order to reduce population declines among Common Terns.

“Because survival is lowest during the non-breeding season, identifying coastal Peru as a potentially important wintering location was significant, as it will help us target studies aimed at identifying potential causes of adult mortality in this region,” said Annie Bracey, a member of the research team.

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By Kay Vandette, Earth.com Staff Writer

Image Credit: C. Henderson