Pliocene and Pleistocene Gulls (Laridae) of the North Atlantic

Ring-billed gulls (Larus delawarensis) often hover over grocery store parking lots in Augusta, Georgia.  The wide open spaces and spilled junk food attract them to these man-made habitats.  They appreciate all the obese Americans who can’t wait to get home to stuff their faces.   The gulls scavenge smashed corn chips and cheese crackers off the pavement.  Gulls perform a valuable service by cleaning up schools of dead fish and mountains of human garbage.  This helps reduce the spread of toxic bacteria in the environment.

Most people think of sea gulls as shore birds, but ring-billed gulls are quite common inland and some may never see the ocean.  Other species of gulls, such as Bonaparte’s (L. philadelphia), follow rivers upstream and can also be found inland.

Ring-billed Gull Photo

Ring-billed gulls are commonly found in parking lots and landfills during winter time in Georgia.

Several species of gulls, including the laughing (L. atricilla) and Franklin’s (L. pipiyan), are primarily shore dwellers and do nest off the coast of southeastern states.  The laughing gull prefers to nest in beach thickets, though many species of gulls and terns will lay their eggs in the open.  Sea gull nestlings are mobile shortly after hatching, so they can avoid predation at an early age.

There are at least 5 species of gulls that have a polar distribution.  I hypothesize some or all of these species ranged as far south as what today is South Carolina and Georgia during the Ice Ages.  Glaucous gulls (L. hyperboreus) are a polar species that prefers nesting on rocky sea cliffs where they can feast upon nestlings of other cliff-nesting sea birds.  Today, there are no sea cliffs off the coast of southern states.  But for about 40,000 years, there was an enormous sea cliff, known as Bulls Scarp, off the coast of South Carolina where glaucous gulls could have nested. (See:  About 13,000 years ago, rising sea level submerged these cliffs, and glaucous gulls likely left the region then.

Adult breeding

Glaucous gull.  This is a polar species occasionally found as far south as Virginia.  During the Ice Age it likely ranged much farther south than it does today and it probably nested on Bulls Scarp, a now submerged sea cliff.

Some paleontologists puzzle over how rare gulls are in Pleistocene fossil sites.  The La Brea tar pits preserved the bones of more than an hundred species of birds but have yielded just 1 gull specimen.  I think I know why gull remains appear so rarely in Pleistocene fossil sites.  Pleistocene shorelines are submerged today. Most fossil evidence of gulls is deep beneath the surface of the ocean.

I am unaware of any extinct species of Pleistocene gulls.  The species that are alive today are the same as the ones that lived during the Pleistocene.  However, there were 2 species of Pliocene gulls that are now extinct.  Fossils of L. lacus and L. perpetis were among bird fossils found at a site on the Florida gulf coast.  The fossils are estimated to be between 2 and 2.4 million years old.  Apparently, all the birds found at this site were killed by a toxic red tide.  (I may do a blog article about this site, if I can ever obtain a reasonably priced copy of the scientific paper documenting it.)

The Larus genus originated in the North Atlantic polar region about 20 million years ago.  Sea gulls have dispersed and have an almost worldwide distribution today.

Tags: , , ,

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: