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The Not-So-Common Loon

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Photo of loon courtesy USFW Photo of loon courtesy USFW

Just how prevalent is this elusive bird in our area?

One of the oft’ talked about critters in our high wooded mountains and sunken, water-filled valleys is the common loon. However, as often as we talk of them, and despite the namesake suggestion that they may be widespread, this particular bird is a rarity and a site to behold upon our waters. The loon is designated as a sensitive species, easily impacted by disturbance—making it even more difficult to get them to come around, let alone stay around. Awareness of this sensitive species heightened in the 1970s after the impacts of DDT on some bird species was acknowledged.

“Contrary to their name, common loons are fairly uncommon in this area,” comments Avista Terrestrial Program Leader Nate Hall.

Common loons occur across Alaska, Canada, and the northern tier of the United States; really there are few in the West. Breeding pairs are found in only four states west of the Mississippi River. Of all the western states, Montana has the largest population with over 200 birds.

The common loon, in the case that you aren’t an avid birder, is a large, goose-size diving bird that spends its summers on open fresh water lakes and winters on the west coast. They are 2 to 3 feet long, weigh 8 to 12 pounds and have a wingspan of 4 to 5 feet. They feed mostly on fish, but also eat other aquatic animals, such as salamanders, leeches, frogs and insects.

Common loons are known for their distinctive calls, three of which are heard on summer breeding lakes: 1) the wail, a long almost mournful cry, 2) the tremolo, a high pitched, rapid, five-beat call, 3) and probably the best known is the yodel, which is given only by males during “territorial confrontations” (i.e. fights).

Courtship between the loons begins shortly after territory re-occupation and involves quiet, shared displays including swimming, head posturing, and short dives. Copulation, once courtship has taken place and the pair is satisfied with each other, typically lasts from three to ten minutes, and takes place on land. Some copulation sites become nest sites. It is believed that pairs re-mate each spring and that courtship serves primarily to renew the pair bond, much like a second honeymoon.

Loons are a good demonstration of reciprocity, as nest-building is conducted by both members of the duo. Egg laying begins one to four-and-a-half weeks after spring arrival and eggs are typically laid at two-day intervals. These birds generally lay two eggs which vary in color from deep olive to light brown in color, marked by irregular dark spots.

Sexes are nearly indistinguishable. The head and neck of breeding adults are black with a luminescent green gloss. The back, wings and sides are also black. The shoulder feathers, or “scapulars” and “wing-coverts” (at the upper and lower surfaces of each wing) have large white markings, which is a distinctive field mark. The eye is red. Common Loons have a broad patch of vertical white stripes on the side of the neck and a smaller patch on the upper foreneck. The breast and belly are white and the bill is straight, heavy and black.

In the non-breeding plumage, the head, neck and upper parts are dark gray to dark brown. The cheeks, throat, and underparts are white. The bill is brownish-gray to pale bluish-gray or horn colored. The iris is brown. The tail is dark brown, and tipped with white. Juvenile plumage is similar to the adult non-breeding plumage, although the upper parts have paler and more conspicuous feather margins than those of adults, and the throat and sides of the neck are more finely streaked with brown. This plumage is worn until the following summer, when the birds molt into more adult-like basic plumage.

In Montana, common loons will not generally nest on lakes less than about 13 acres in size or over 5,000 feet in elevation. Successful nesting requires both nesting and nursery areas. Small islands are preferred for nesting, but heavily vegetated shorelines are also selected. Most Montana lakes inhabited by common loons, as reported by the Montana Loon Society, are relatively oligotrophic (low on the production scale).

The quantity and quality of nesting habitat limits the loon population of northwestern Montana, reports the Montana Loon Society; they estimate the state’s “carrying capacity” at 185 potential nesting territories, based on the size and number of lakes within the species’ breeding distribution.

Up to 86 lakes in Montana have had at least one pair of common loons present during the breeding season and up to 33 lakes have had common loon chicks present. On an annual basis, about 160 to 180 Common Loons can be found on Montana lakes. Between 1999 and 2001, 60 to 80 percent of these adults formed territorial pairs, but less than half produced chicks.

There is not a lot known about the few loons that nest in Northwest Montana (north and east of the Lower Clark Fork watershed, near Troy and in the Thompson chain of lakes), reports Hall. “Within the past 10 to 15 years, we have increased awareness of their needs, especially regarding nesting,” he says.

During the relicensing process for the two dams on the Lower Clark Fork River, loons had been occasionally observed in Lake Pend Oreille and the Cabinet Gorge and Noxon Rapids reservoirs. As a result, Avista conducted a survey for five years in the Reservoirs, as well as in the Clark Fork Delta. The survey was conducted every week or two during breeding season, which is April through June.

Based on the surveys, along with asking volunteers to observe, it was discovered that the loons do, in fact, have “stop-over sites” during migration, but there is no nesting on the reservoirs. Now, Avista conducts the surveys only on established loon-monitoring days; mid-May to determine if nesting sites exist, and in mid-July to count numbers of young hatchlings in the reservoirs and the Clark Fork Delta.

“The results of the survey weren’t surprising,” says Hall, “as loons have a high affiliation with the lakes where they were born.”

Because they are a more lake-like nesting bird, the reservoirs were not lake-like before the dams; loons were not nesting there historically. Lake Pend Oreille might have more potential for nesting loons because it’s always been a lake.

“They don’t generally pioneer new areas, which is one reason why the populations are struggling,” says Hall.

In the reservoirs, the peak number of individuals counted to date is around 20 in early to mid-April on their way to Canada. They also see a few in July, when the “unsuccessful nesters” return to the area. The numbers peak again in October when they are heading south, to San Francisco, Baja, or other large lakes in the New Mexico area.

On Lake Pend Oreille and throughout the Panhandle, common loons are seen mostly during migration periods. When a sighting is reported in the summer, Idaho Dept. of Fish and Game non-game biologist Sonya Knetter says they really key in, as that suggests they could be nesting. “Since they are known to nest in Washington and Montana, it would suggest that they nest here, but we have yet to confirm a nest location,” she says.

In Idaho, common loons are recognized as a “species of the greatest conservation need,” which is identified in the Comprehensive Wildlife Conservation Strategy (see it online at http://fishandgame.idaho.gov/cms), a plan that guides conservation efforts for states that receive federal funding. There are several locations in the Panhandle where IDFG and other entities have placed “nesting rafts” (artificial nesting platforms) for loons. In Lake Pend Oreille, there is a loon raft in Denton Slough.

Young loons reach maturity at three or four years; the juveniles spend their first few years in the ocean. Then, when the nesting urge kicks in, the females leave for their native lakes. The males follow. Loons migrate through Montana in route to Canadian lakes and can be observed on large reservoirs and lakes in many parts of the state during the spring and fall seasons.

Loon chicks rest, feed, and grow in and around the territory where they were born during the months of June, July, and August. Look for them in backwaters and along the shoreline. Young chicks are not waterproof. They need to be able to climb up on their parents’ backs to stay warm and dry. When watercraft comes close, parents leave their chicks to defend their territory. This also leaves them vulnerable to being snatched by eagles, large fish, or other predators. Young chicks are very buoyant. They can’t dive quickly to get out of the way and can be run over. Chicks tire easily. The presence of watercraft causes them to keep swimming instead of feeding and resting; this can weaken their ability to survive. If you are boating and see loons, back off and view them from a distance.

“Human influence and boating activities are likely one of the greatest influences on loons in our region,” says Knetter. “Shoreline development surely has an impact, as loons are known to nest on the shorelines and islands.”

Loon parents leave the nest if watercraft come within 150 yards (1.5 football fields), leaving the eggs without warmth or protection. If disturbed often, loons abandon the nest. A pair may re-nest if it isn’t too late in the season, but they only have time for one more try. If two loons are seen together in May or June near an inlet, marshy cove or backwater, a nest site has probably been disturbed.

Loons let you know if you are too close. Their distress calls sound like laughter. If you see a loon “dancing,” flapping its wings and raising its chest out of the water, it is no laughing matter and is urgent that you move away.

Lead sinkers from anglers cause many mortalities for common loons, reports Hall. They dive down for fish, catch the sinkers, and get lead poisoning. Also, loons are very susceptible to boat traffic and people getting too close. They will flee the area and often not return. Onlookers are urged to enjoy them from a distance.

For more specific viewing information contact Montana Fish Wildlife and Parks at 406-752-5501. In Idaho, to get more information or report a sighting, call the Coeur d’Alene Regional Office at 208-769-1414.

Statewide in Montana, the numbers of common loons are “stable to decreasing,” says Hall. This special bird, if most numerous in Montana of all of the western states, needs our protection more than ever. You can help by learning to identify them, report sightings, but most importantly, by keeping your distance.

Loon photos on pages 1 and 8 courtesy of USFW.

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Author info

Kate Wilson Kate Wilson was a Project Journalist for Avista's Clark Fork Project. She has been interested in environmental issues since she was a youngster.

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