Diving Birds

Joe Meche is a member of the board of directors of the North Cascades Audubon Society and has been the editor of the chapter newsletter for the past six years. Joe has been photographing birds and landscapes for over thirty years and has been watching birds for more than fifty years.

Through millions of years of adaptive radiation, birds have adapted to the habitats they frequent and to their dietary needs. Bill and wing shape, feet and legs—every part of a bird is about the form and function that evolved to suit the needs of a particular species to survive. To fully appreciate the evolutionary process and to see how well adapted birds are to their environment, consider not only the similarities between species, but take the time to notice the subtle differences as well.

As you marvel at these adaptations you’ll derive a great deal of pleasure while you enjoy the birds. Of all the bird species, some of the most impressive adaptations are those of the diving birds. They are completely at home in their watery environments and are often more inclined to dive rather than to fly away when predators are about. According to studies, there are over 390 species of birds in nine orders that swim, and two-fifths of those dive for food. While most birds share similarities when it comes to the basic principles of flight, the adaptations needed for swimming and diving are quite different.

Some birds must plunge from varying heights to get below the surface to capture their prey, and their buoyancy tends to make them pop up to the surface like a cork. Diving birds tend to be heavier than surface feeders and they submerge completely with quick, arching dives from the surface. The typical diver’s body is more streamlined, long and cylindrical, with the center of gravity placed toward the rear. The legs of the divers are set farther back on their bodies to propel them through the water with maximum efficiency. While some divers use just their feet for propulsion, a few species use their wings to swim and steer underwater.

The characteristic that makes some of the divers so efficient underwater causes them some degree of difficulty when they are out of the water. With the legs set so far back on their bodies, loons and grebes have great difficulty walking. For this reason, loons and grebes prefer to make nests that are more of a floating platform than anything else, making it easier to get in and out of the nest.

The length of time that diving birds spend underwater and the depths to which they dive vary according to species. Emperor penguins, for instance, have been known to dive to maximum depths of 265 meters and remain underwater for over 18 minutes. These are most certainly extremes since most dives are relatively shallower and of much less duration. Along with the physical adaptions that enable these birds to dive and swim underwater is a remarkable array of physiological traits that regulate body temperatures and heart rates as the birds pursue their underwater prey.

Some diving birds have an unusual tolerance to asphyxia, or lack of air. They can reduce oxygen consumption considerably and ration it sparingly during prolonged dives. For some, blood flow to a number of organs stops during dives and the birds rely on anaerobic metabolism during this period. Selective constriction of parts of the vascular system and a slowdown of the heart rate begin within six seconds of immersion of the head. This diving reflex is triggered when water touches special receptors in the nares, or nostrils.

From the perspective of a birdwatcher, the diving birds are some of the most interesting to observe for long periods of time. The action can turn into a feeding frenzy when large numbers of divers congregate above a traveling school of fish. Birds are constantly diving and surfacing and diving again to avail themselves of the food below. As you observe the action above the surface, try to imagine the scene underwater!

Whatcom County is home to a number of diving birds, and late fall through early spring is the best time of year to observe most of these incredible birds in action at a number of sites. This is the time of year when the divers can congregate in large numbers and appear at times to cover the surface of the water. This group of birds includes the loons and grebes, cormorants, the alcids, all of the sea and bay ducks, and some of the freshwater ducks.

Loons are known through parts of the world as the great northern divers, or simply, divers; and that’s what they do, as well as or better than any other species. Loons are heavy-bodied birds and, to many, the true essence of wilderness. The haunting calls of a pair of nesting loons on an inland lake are appreciated most from the comfort of a sleeping bag. Red-throated, common and Pacific loons are regular winter visitors, and the occasional sighting of a yellow-billed loon creates quite a stir among serious listers.

There are six grebe species that can be found in local waters, but only the pied-billed can be found year-round. The western, horned and red-necked grebes are common in winter while the eared grebe is seen locally during migration. Western grebes have numbered in excess of 20,000 birds in previous years on Bellingham Bay, but their numbers have been in serious decline for the past few years. The less common Clark’s grebe can sometimes be found in flocks of western grebes, but close inspection of the flocks is essential.

Three species of cormorants frequent the marine waters of Whatcom County. Double-crested and pelagic cormorants are common in the area throughout most of the year and nest locally, while Brandt’s cormorants are more common as winter visitors from August to May. An increasingly large nesting population of double-crested cormorants can be found on the breakwater around the Blaine marina. Double-crested cormorants can also be found on the larger freshwater lakes in the area.

The alcid family is interesting because alcids use their wings when diving and practically fly underwater in pursuit of prey. Alcids are usually farther out on the open water and difficult to see from shore. A good scope is essential for viewing most species from shore, but ferries and other boats that cross stretches of open water provide excellent opportunities for viewing a number of these fascinating birds.

In local waters, some of the alcids that you might encounter are the common murre, pigeon guillemot, marbled murrelet and the rhinocerous auklet. On boat tours through the San Juan Islands, a real delight is the occasional sighting of a tufted puffin. The marbled murrelet is a threatened species that depends on old growth forests for nesting sites. The nest is usually situated high in a conifer and the two adults will fly back and forth from the nest, as far as 40 miles inland, to feed a single chick.

Sea and bay ducks gather in county waters in impressive numbers in winter. Some of the best viewing areas are anywhere on the perimeter of Drayton Harbor, as well as the outside of the Semiahmoo Spit. The single best location is the recently refurbished public pier at the end of Marine Drive at the Blaine Harbor area. From this vantage point, you can scope the channel between Blaine and Semiahmoo and the entire expanse of Semiahmoo Bay, all the way to White Rock, B.C. In early to mid-April the south end of Birch Bay, near the southern boundary of Birch Bay State Park, hosts large concentrations of diving species and accompanying gulls. The birds gather here to feast on the annual herring spawn.

Notable among the diving sea and bay ducks are three species of scoters, long-tailed ducks, two species of goldeneyes, two species of scaup, red-breasted mergansers, the inimitable harlequin ducks and the diminutive bufflehead. Species that tend to frequent freshwater habitats more than salt include the common and hooded mergansers, ruddy ducks, ring-necked ducks, redheads and canvasbacks.

The majority of the diving birds that we see on saltwater during the winter share a unique characteristic, in that they nest and breed on freshwater lakes and ponds. Along with the heavier body, which is important for diving, their relatively smaller wings make it necessary for the divers to have a suitable runway to take off. They are unable to explode from the water in the manner of the dabblers.

The large concentrations of diving birds on local waters in winter played an integral part in establishing several sites in Whatcom County as part of the Great Washington State Birding Trail’s Cascade Loop. These same numbers were also important in the designation of Drayton Harbor and Semiahmoo Bay as one of fifty-three Important Bird Areas in the state. This area has recently had some of the heaviest concentrations of waterfowl in years. In late February and March, between 1,500 and 2,000 loons of three different species were observed in the area. Along with the loons were large numbers of cormorants, and all the diving ducks you could expect to see in this area.

When other birds might be harder to find during the winter months, pack a lunch, binoculars, and your scope and spend some time with the diving birds. If you prepare properly and dress accordingly, you’ll be hard pressed to find a group of birds that will provide more entertainment. §