Creature Feature: The Red-Throated Loon
The red-throated loon (Gavia stellata)is the smallest, most widely distributed, and most distinctive of the world’s five loon species. Annually migrating from summer nesting sites in the Arctic reaches of North America and Eurasia to wintering grounds in the Lower 48, Mexico, Europe, and Asia, this bird can really move.
It's sociable too, migrating in flocks as large as 1,000 birds. Unlike many migratory species, the red-throated loon is not hunted for food or sport – one big reason being that this fish-eating bird’s flesh is not very palatable.
While usually known as the red-throated loon in North America, this species is widely known as the red-throated diver in Europe and goes by many local or regional names such as rain goose, Cape drake, and little loon. Whatever name it may bear in a given area, the species is widely distributed in northern Europe and Eurasia as well as North America.
The red-throated loon differs from other loons in some noticeable ways. It is smaller, being only about 21 to 27 inches in length with a wingspan of 39 to 47 inches. A typical adult red-throated will weigh a few ounces over two pounds. The sexes look alike, though male birds are slightly larger.
When you see the red-throated take to wing you’ll notice that it doesn’t need the long watery runway that other loons do to get airborne. The red-throated can take flight in relatively tight spaces and even from dry land. (This doesn't mean that it can walk with ease on dry land. The word "loon" derives from the Scandinavian lom, which means "clumsy.")
Vocalization is distinctly different, too. Instead of producing classic loon “laughter,” the eerie “call of the wild” sound that males of other loon species make, both male and female red-throated loons produce (sometime together) a range of sounds from yodeling or wailing to bizarre growling. You can hear a sample at this site.
Another difference is that adult red-throated loons don’t transport their young on their backs the way other loons do. Red-throats mate for life and return to lay eggs in the same place year after year. Both parents care for the young.
The red-throated loon will consume crustaceans and other targets of opportunity, but it is basically a fish-eating specialist. It can subsist quite nicely on fresh water species, but prefers to dive for small fish in the sea. This sea-hunting trait allows it to nest in the vicinity of coastal bogs and ponds too small to meet its nutritional needs. The nesting birds just fly back and forth to the sea for feeding, sometimes traveling considerable distances.
The red-throated is a good diver. It can remain under water for more than a minute, easily descending to 25 feet and sometimes as deep as 70 feet. People not used to watching feeding red-throats are surprised when they see them swimming crocodile-fashion with all of their body submerged except for the eyes and thin, upward-tilted bill. To facilitate this, the bird’s bill is equipped with narrow, elongated nostrils on top.
Like many other birds, the red-throated loon changes its plumage with the seasons. During the summer breeding season it has a dark body with white underside, a grey head, and of course, a red throat on its thick neck. Once mating is over, the bird molts and is nearly immobile for several weeks. As new wing feathers grow in, the plumage transitions to the more demure grey color that dominates in the non-breeding part of the year.
The red-throated loon must keep its plumage in tip-top condition. If it cannot replenish oils in its feathers every few hours, it won't be able to stay warm in the cold water and won't have the right degree of buoyancy for swimming and diving. The birds consequently spend much of the day grooming and preening. It’s fun to watch their carefully orchestrated bathing exercises, which have been described as "extreme preening." Designed to give the feathers a good flushing, this process may be as simple as sticking out one wing and going in circles or it may involve energetic rolling or somersaulting in the water.
A red-throated loon starts its life as a fluffy hatchling in the Arctic, usually in a nest that is close to a small pond or bog and not far near the coast. Nature’s clock ticks fast for the little bird, which must grow very quickly if it is to survive. The young bird takes its first flight at seven or eight weeks, and by the tenth week it is almost a fully functional adult and no longer receiving parental care. It may take up to three years, however, before it becomes fully mature.
It is thought that the North American population of red-throated loons may be declining. Scientists are not sure, however. There is a scarcity of scientific data about population levels and trends, longevity, and other key variables. Only about 500 loons have been banded and tracked.
During the 1800s and early 1900s, fishermen considered all loons to be pests. Hunters killed thousands of common loons (Gavia immer) and red-throated loons every year in America until the Migratory Bird Treaty Act of 1918 put a stop to that. Now the red-throated loon must contend with a variety of other hazards. Botulism outbreaks sometimes kill thousands of loons during the seasonal migrations. Commercial and recreational fishing accounts for many loon fatalities. Some birds drown after getting entangled in fish nets or fishing lines, or after grabbing fish lures or minnow-baited hooks. Many loons die of lead poisoning after ingesting lead fishing sinkers they mistake for the small pebbles they must swallow to help break down fish bones in their gizzards.
Another significant threat to this sea-going bird’s well-being is oil spills. As the 1989 Exxon Valdez oil spill in Alaska’s Prince William Sound illustrated so vividly, oil in the ecosystem can spell doom for many water birds. If a diving bird like the loon acquires a coating of crude oil while resting on the water or swimming, it is unlikely to survive. Freshly spilled oil can be toxic when the bird ingests it while trying to clean itself. More ominously, the oil also ruins the insulating and buoyancy-producing properties of the bird’s feathers. A badly oiled bird cannot dive to feed itself and cannot stay warm. It is likely to starve to death if it does not die first die hypothermia.
There are other hazards as well. Habitat destruction and degradation pose significant risks in areas where uncontrolled development, wetland drainage, and other human activities reduce the amount and quality of wetland habitat. Acid rain degrades the water in ponds and bogs, reducing the availability of food for the loons and increasing their risk of heavy metals contamination. Like other fish-eating birds, loons are also susceptible to being poisoned by toxic chemicals through the biological amplification of harmful chemicals and heavy metals in polluted water. The mercury released into the air by coal-burning power plants is a prime example. The mercury ends up in the water, then in the fish, and then in the loons that eat the fish. In sufficient concentrations the mercury can reduce the birds' breeding success and their ability to care for their young. Global warming is another serious long-term threat, since it can drastically affect the number and distribution of the bird’s preferred prey fish.
The long-term outlook for the red-throated loon remains pretty good, so it shouldn’t be turning up on the threatened or endangered species lists anytime soon. Still, ensuring that future generations will be able to enjoy this bird requires that we practice responsible stewardship. Protecting against habitat destruction and degradation in both nesting and winter habitat areas is vital. Thus, for example, wilderness preservation in places like the Arctic National Wildlife Refuge will help to ensure their reproductive success. In some places where natural nesting places are inadequate it may be necessary to provide artificial ones. This strategy has enjoyed conspicuous success in Scotland, where raft-like nesting platforms have been built for the birds.
If you want to enjoy red-throated loons at firsthand, several options are available. During the seasonal migrations it is possible to see passing flocks of birds or birds that are resting and feeding in the flyway refuges. You could go to the high latitude breeding grounds in the summer, though that is a tad expensive. Many people find it best to seek out the birds in places like national parks that have resident populations during the winter. Among the Pacific Coast parks that offer this opportunity are Olympic National Park, Golden Gate National Recreation Area, and Channel Islands National Park. In the upper Great Lakes and north central states, Voyageurs National Park and Isle Royale National Park make good choices.