Horned grebes are returning to our coastal waters, and even to some of our inland lakes. Red-necked grebes have been back in Maine since late August. Now, I know what you’re thinking. What’s a grebe?
Good question. We’re not exactly sure.
Grebes are water birds that feed on small fish and crustaceans. For a long time, we presumed they were related to loons, since both are foot-propelled divers. Thanks to DNA analysis, it looks like they might be most closely related to flamingos.
Wait, what? Flamingos?
There are 22 species of grebes worldwide. Three are commonly found in Maine. Pied-billed grebes are temperate zone breeders that nest here in summer. They prefer small, reedy marshes. Red-necked and horned grebes are subarctic breeders that winter here, mostly in saltwater. You can find them along the Maine coast right now. Red-necked grebes have longer necks and bills, giving them a loon-like appearance. They sometimes congregate. Horned grebes are smaller, and they tend to be solitary.
Grebes have lobed toes. Each toe has webbing, but the webbing does not connect between the toes, as it does for ducks, geese and loons. The fact that all these birds have some kind of webbing is considered evidence of convergence. Convergence is what happens when unrelated species occupy the same niche, and therefore evolve similar characteristics.
The similarity ends there. Grebe plumage is dense and waterproof. Their feathers lie at angles to the body so that they can squeeze out the water, enabling the bird to adjust its own buoyancy. A grebe can choose to dive nose first into the depths, or simply submerge out of sight. It can swim so low in the water that only the head is exposed.
The longer scientists puzzle the grebe lineage, the more signs they find that grebes and flamingos are related. Besides genetic similarity, the birds share certain characteristics that are rare among other species. These are obscure, and so weird that most of us would wonder why it matters.
For instance, primary feathers are the long flight feathers positioned lengthways along the outer parts of the wing. Most birds have nine or 10 primaries. Grebes have 11. Only flamingos and storks share this trait.
Grebes and flamingos have peculiar toenails that are unlike any other species. Their eggs are covered in a chalky coating, which is unique in the avian world. Scientists have even found a type of lice that lives only on grebes and flamingos.
Flamingos build mud nests. Grebes build grass nests. Not much similarity there. But in 2012, scientists found the fossilized remains of an ancient flamingo nest. It was made out of vegetation, much like a modern grebe’s nest. This was more evidence that grebes and flamingos can be traced back to a common ancestor.
Trying to figure out the evolutionary family tree of a bird seems like an odd science, best practiced by compulsive old professors in tweed jackets. But there are practical implications.
When scientists determine that a tall wading bird and a small diving bird likely spring from the same ancestor, it sparks the question about how fast evolution actually happens. In today’s world, we watch evolution occur when bacteria develop resistance to antibiotics. We watch it happen when the Zika virus mutates sufficiently to jump from monkeys to humans.
One thing is for sure. Grebes are still evolving. They are becoming better swimmers and poorer flyers. Like loons, their legs have moved farther back on the body, allowing them to swim underwater more efficiently, but making walking almost impossible. They rarely try to evade danger by flying, preferring to dive out of trouble. Two species in South America have lost the ability to fly altogether.
Comically, we now know more about the origin of the grebe than we do about its name. The word is found in French books of the mid-1700s, but no one knows for sure where it came from.
The Online Etymology Dictionary speculates that it comes from the Breton word “krib,” meaning comb, since some grebes have crests. The horned grebe that is now moving into our bays has little feathery crests in breeding season that resemble horns. Its western cousin, the eared grebe, has similar crests that look like tiny ears.
So when you’re doing a little oceanside birding this winter, and you spot something that looks like a small loon diving, you can giggle along with me when you recognize that grebe as the closest living relative to a flamingo.
Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.com.