Diving for a Living
BIRDS make their living in different ways. However, those that dive for a living are probably the most fascinating to watch.
Some birds use the sky seemingly as a giant slide, plunging headlong into the water from great heights to grab their prey. Others skim the surface, picking up their meal as they go. Still others may sink slowly beneath the surface without leaving a ripple, and then pursue fish underwater, overtaking them.
High-diving honors should probably go to the three-foot-long gannet. This white thunderbolt with black wingtips plunges on its prospective meal from varying heights, depending on how deep the fish is swimming. He may dive into the water from only a few yards in the air. Or he may streak headlong from a hundred feet, completely closing his six-foot wingspread an instant before hitting the water. The impact is with such force that sometimes spray is sent ten feet into the air. What a thrilling spectacle to behold!
The depth to which the gannet can descend is indicated by the fact that he has been caught in fishermen’s nets ninety feet underwater. But he usually surfaces after a few seconds, and rests on the water just long enough to swallow his catch. Then he rises in pursuit of other game.
The pelican is another high diver, although this may be difficult for one to believe when observing him on land. Trying to walk about on his short, stout legs, the pelican is as awkward as any circus clown. And his gigantic bill, with the large elastic pouch hanging beneath, only adds to his comical appearance. But in the air the picture is entirely different. He is extremely graceful, and at great heights exhibits a power and dignity equaled only by the eagle. His five-foot white body and eight-to-ten-foot wingspan make him indeed a rare beauty in flight!
The brown pelican, somewhat smaller than his white relative, is the diver of the family. When spying fish, often from as high as fifty feet, he folds his wings and hurtles downward at great speed. But despite the force of his dive, he descends no deeper than about two feet because of the buoyancy of his body. Nevertheless, he seldom misses scooping up fish in his pouch.
The pelican comes up with, not only fish in his pouch, but perhaps three or more gallons of water. Frequently gulls or other smaller seabirds are right there waiting. And as the huge pelican opens his bill to let the water out, they perch on his back or head and reach right in and grab the fish. So the pelican’s hard work can go for naught if he is not careful.
Another high diver, the osprey or fish hawk, has a similar problem. After he makes his catch, the bald eagle, if he is in the neighborhood, will use his superior size and power to force him to relinquish it. This does not mean that the osprey is small or is a weakling. He is really a big fellow, having a wingspread that may reach six feet. So his dive is a real spectacle, especially if it is from three hundred feet or more, which is not uncommon.
When spotting a fish near the surface, the osprey will take aim, close his wings, and dive headfirst, but with his feet forward. He hits the water with a great splash, and often goes completely under. Usually he surfaces quickly with a catch firmly grasped in his talons. But he has been known to misjudge.
Once an osprey was observed to sink his talons into a larger fish than he could handle. So instead of coming up, the fish pulled him under. Finally the osprey was able to free his talons and reach the surface before he drowned. But he lay down for ten minutes before recovering sufficiently to fly again.
A considerably smaller diver, but no less daring or graceful, is the kingfisher. He will wait motionless on a dead branch of a tall tree, his sharp eyes scanning the water perhaps fifty or more feet below. When an unwary minnow or other small fish ventures near the surface, he plummets headfirst to seize it with his long bill. The kingfisher can also fly along and, when sighting a meal, halt, hover briefly, and dive like an arrow.
A welcome sight to fishermen is a flock of terns hovering and plunging into the sea. They feed on small fish that often are driven toward the surface by schools of larger ones below, hence the interest of fishermen. These relatives of gulls are so graceful in flight that some people call them sea swallows.
A truly unique fisher is the skimmer, a black-and-white seabird that resembles the tern in several respects. But unlike all other birds, the skimmer has a vertically flattened, knifelike bill, with the lower half considerably longer than the upper. Thus the nickname “scissorbill.” This unusual bill is employed in a unique fishing style.
The skimmer will fly along the water for perhaps a hundred yards with his lower bill just slicing the surface. This attracts small marine creatures. Then he will return, scooping up these creatures with his lower bill as he skims along the water. The bill closes on contact, so the skimmer resembles a dressmaker at work with her cutting shears.
One of the most interesting deep divers is the two-to-three-foot-long, powerfully muscled cormorant. His plumage is predominantly dark, often black with a greenish and blue sheen. And his bill is long, and has a hook on the end. He is related to the pelican.
But, unlike the pelican and other high divers, the cormorant dives from the surface or a low perch. While swimming he will spring upward and forward, and enter the water in a graceful curve with wings pressed close to his sides. He may sight his prey before diving, or he may dive first and then look around underwater for fish. Using both wings and feet for propulsion, he pursues and overtakes his prey. Sometimes he dives to great depths, one cormorant being caught off the coast of England in a crab pot 120 feet below the surface!
Taken when young, cormorants have been trained by fishermen to catch fish for them. This practice once was common in England, and it has long been known in the Orient. A band is placed fairly loosely around the cormorant’s neck to keep him from swallowing anything but very small fish.
Among the best divers of all are the grebe and the loon. They both have some of the same characteristics, notably skill in the water and clumsiness on land. Their legs are placed far back on their bodies, excellent for diving and swimming, but making them almost helpless on land. And since the loons are unable to take flight from land, being forced to the ground far from water usually means death for them.
The diving motions of the smaller grebes are fascinating to watch. They sink quietly and quickly from sight, without a sound or ripple. One minute they are perched on top of the water, and the next they are gone. An observer may wonder if he really saw them. And if he waits he may conclude he never did, for they may not appear again. They can stay submerged for a long time, swimming a distance away underwater. Then they will cunningly rise to the surface, just sticking up their bill and eyes so that they are difficult to see.
The loon is larger, about three feet long, and is probably the champion deep diver of all birds. He literally flies underwater, propelled like a bolt from a crossbow by his powerful wings. The loon can overtake the swiftest fish. And he can remain underwater several minutes to pursue his prey to almost unbelievable depths. Loons have been caught in fishnets set at over 160 feet below the surface! And it is believed that they go much deeper.
We may have thought of birds as at home only in the air. And while the tern, the osprey, the pelican and other water birds are among the best of fliers, some are also remarkable divers. A few even rival fish in their underwater mobility! No wonder they are so successful in diving for a living.