JUST ANNOUNCED: Jason Cale Band will be playing our Best Of event! Grab your tickets now before they are gone!

Rain-covered streets can cause unintentional grounding

My neighbor was insistent. There was an unusual black bird with a large beak stranded on the driveway. As I trudged down the block, fully expecting to find a grounded baby starling, I mentally prepared my standard lecture on leaving baby birds alone.

Instead, an enormous Double-crested Cormorant greeted me. What was this fish-eater doing miles from the river, waddling penguin-like on the cement with its short wings spread nervously in preparation for flight?

Cormorants and many other diving birds, such as loons and grebes, cannot achieve flight unless they run along the surface of water to gain speed. This is because their feet are located so far back on their bodies that they cannot gain sufficient forward momentum when running on land. Imagine an airplane cruising down a runway without an accelerator.

This unusual anatomical placement of diving birds’ feet is the result of million of years of natural selection. For the same reason that we place outboard motors at the very back of our boats, mutant cormorant ancestors with feet slightly farther back on their bodies were able to pursue fish more quickly under water, and thus left more offspring. Because these birds rarely leave their aquatic environment, except to waddle a few feet to their nests, the disadvantage of not being able to take off from land were far outweighed by the increased effectiveness of their paddling feet.

The advent of paved roads that mimic rivers when covered in water has led to a phenomenon in which these waterbirds mistake the rain-covered asphalt for aquatic habitat and unintentionally ground themselves. This is likely what had happened to my neighbor’s cormorant, as there had been a torrential rain the previous day.

I was able to bring the mildly injured, but very spirited cormorant to a rehabber, where it will soon be released on the open water. But many birds are not so lucky.

During migration, grebes and loons that run into storms may descend by the thousands onto wet highways, often breaking bones as they do. Whether injured or not, these birds are completely helpless unless they are rescued by people and returned to a large body of water. Such mass groundings have occurred in western Virginia in recent years, but are more common in the arid western U.S., where real bodies of water may be far outnumbered by wet roads or snow-covered parking lots.

If you find a downed waterbird, throw a blanket over it, gently cradle the bundle under your arm, and immobilize the dangerous fish-spearing bill by holding the bird’s neck away from your face.

If the bird appears reasonably healthy, release it immediately on the shore of a large lake or river, where it can catch fish while it recuperates. Small neighborhood ponds, while they may contain plenty of fish, are not sufficiently long to allow these birds to gain take-off acceleration. If the bird is clearly injured, call a local veterinary clinic and ask for information about wildlife rehabbers in the area. It is illegal to possess wild birds, their eggs, feathers or parts, so do not try to rehabilitate the animal on your own.

Cristol teaches in the Biology Department at the College of William and Mary and can be contacted at dacris@wm.edu. To discover local birding opportunities visit williamsburgbirdclub.org.

Copyright © 2018, The Virginia Gazette
64°