The Common Tern

Connecting the Gulf of Mexico to the Boreal Forest
Common Tern flying over water.

One of the United States’ ecological treasures, the Gulf of Mexico region supports a vast array of bird species, many of which use the Gulf at some point in their life cycle, for breeding, overwintering, or as a migratory stopover. Unfortunately, birds were severely impacted by the 2010 BP oil spill in the Gulf, and recovery is still ongoing. Many of the birds most affected fly long distances throughout the hemisphere, so to help them recover we must think outside of the Gulf region and beyond US borders.  

Stretching across the continent from Alaska to Newfoundland lies North America’s Boreal Forest, a critically important breeding ground for billions of North America's birds. Although many people may envision a myriad of songbird species such as Yellow-rumped Warblers, White-crowned Sparrows, or Rusty Blackbirds when thinking of the Boreal, the biome is also the summer home to large numbers of species we typically think of as seabirds, such as the Common Tern—one of the birds impacted by the oil spill. Each year many avid birders specifically seek out these striking birds with their beautiful white bellies, black caps, red bills, and forked tails, which nest in small colonies on lakes across the southern reaches of the Boreal Forest. 

At least 20,000 Common Terns are estimated to breed on small islands in the lakes and large rivers of this region, and they travel quite a distance to get there, flying thousands of miles north through Central America and across the Gulf of Mexico to return to their breeding sites in the Boreal every spring (explore their migration route on the Bird Migration Explorer). One particularly important nesting area for Common Terns is the Boreal Forest region of Manitoba including places like the so-called “Great Lakes” of Manitoba (Lakes Winnipeg, Winnipigosis, and Manitoba) and large lakes within places like the Seal River Watershed and the Pimachiowin Aki World Heritage Site. This striking bird can be seen flying gracefully over these waters, head turned down at a right angle searching for food beneath the glassy surface. When it sights a small fish, it makes an impressive dive to catch its aquatic prey. It is no wonder people love to marvel at the sight of these remarkable birds.

The Common Tern nests in colonies on islands and lays two or three spotted olive-buff eggs each year. Sensitive to disturbance during the breeding season, whole colonies often fail to breed successfully because of disruption by humans or predators; one reason behind their slow decline in numbers in many regions. Oil spills, such as the one in the Gulf of Mexico in 2010, have also had an impact on Common Tern populations. Vast numbers of the terns, including those that nest in Manitoba, rely on the Gulf as a stopover location to rest and refuel during migration. When spills happen, the birds pick up oil on their feathers as they dive into the water to catch their prey. The oil is then ingested as they preen and can even be carried thousands of miles to their nests in Canada.

Keeping the Common Tern’s summer nesting sites in the Boreal protected is an important part of reversing their decline and hopefully, restoring their populations. Fortunately, Indigenous governments and communities are leading efforts to protect their traditional territories across vast landscapes where these and many species breed, including in Manitoba. Indigenous-led conservation in Manitoba has led to the protection of the millions of acres of the Pimachiowin Aki World Heritage Site and millions of acres more are being considered for conservation in the Seal River Watershed and other areas. Recently, the US federal and state agencies tasked with restoring species injured by the 2010 oil spill proposed a project to fund Indigenous Guardians to protect and manage nesting Common Terns at key colonies in Manitoba. Through hands-on stewardship and monitoring, the project aims to help 2,000 nesting pairs of Common Terns produce more baby birds that survive to fledge from their nests. More babies results in a stronger, healthier population overall that can recover from the losses that the oil spill dealt. 

Conservation projects like this and others across North America, the Caribbean, and Central and South America not only protect vast landscapes that people, birds, and other wildlife rely on locally but also contribute to a larger hemispheric approach to conserving the places migratory birds, like Common Terns, need throughout their entire lifecycles.

Help birds, like the Common Tern, recover from the BP oil spill by taking action today.