Haunting calls symbolic of wild lakes, and they have distinct purposes

Fri, 06/27/2014 - 09:44

(Photo courtesy Paul Cyr)

Anyone who has spent time on Megunticook Lake is familiar with common loons. Their haunting calls are symbolic of wild lakes across the Pine Tree State. Throughout human history, vocalizing loons have enchanted us, especially at night. The ringing tremolo suggests maniacal laughter; the wail sounds like the distant cry of a distressed person. Despite their humanlike qualities, though, loon vocalizations are acoustically complex and poorly understood by people.

Even when not vocalizing, loons are highly charismatic birds. They are strikingly handsome in appearance: clad in black with lines of bright white ovals on their wings, intricate white necklaces on the sides of their long necks and delicate white “chinstraps.” Their mesmerizing burning red eyes can see equally well above and below water. Kayakers and canoeists most often encounter loons foraging, diving a minute or more in pursuit of fish and crawfish underwater. Known in Europe as the Great Northern Diver, loons are propelled by their powerful legs and webbed feet, which can take them to depths of 200 feet. After watching the speed and agility of a loon passing beneath one’s canoe, it’s easy to pity a yellow perch or a small bass. Loons are an iconic species in Maine, loved and admired by humans who share our lakes with one of the planets oldest living birds.

One of the most captivating features of loons is their remarkable voice. Loons are most vocal from mid-May to early-July (height of the nesting season). They have four distinct calls to communicate with their mate, youngsters and neighboring loons; these are the tremolo, wail, yodel and hoot.

To listen to the four loon vocalizations, click on this Cornell University link.

The Tremolo

The tremolo, a palpitating vibrato, is often called the loon’s "laughing call" or “crazy laugh.” However, the call represents the opposite of laughter because the tremolo is an alarm call, often produced at night to vocally advertise and defend its territory against intruders. It’s most frequently given during threatening situations, such as when a boat approaches too closely to a chick or a nest. Tremolos are frequently given to draw intruders away from the chicks by distracting them to the location of the disturbance.

Flying loons also produce tremolos — especially loons being chased from another’s territory. The tremolo commonly triggers a "nocturnal chorus" among loons. Members of a pair will duet using tremolo calls. Tremolo duets are performed by pairs when young are threatened, but also as a territorial proclamation in early spring. Adults give this call especially while dancing nearly upright or running across the water. Tremolos may also be given in association with escape by diving or take off. Tremolo Types I, II and III vary in intensity and generally are in order of the birds increasing concern and agitation. If given in the presence of a human, the loon is very upset and should be left alone. If the human disturbance continues, loons may leave its nest, exposing its eggs or young to predators. If disturbance happens repeatedly, loons will completely abandon their nest site.

The Wail

The wail, which sounds like the howl of a wolf, is two or three note call used in situations when loons move closer to one another, or when one loon is attempting to maintain contact with another or trying to locate a mate or a chick. Parents will wail to their chicks to encourage them to leave the nest, approach the parents when they have food, or emerge from a hiding place. It’s the loon version of “come here” and “here I come.” The wail has also been called the night call, and the storm call.

The Yodel

The yodel is the territorial call of the male loon. Females do not yodel. The yodel consists of loud undulating notes. This call is used in establishing territories, establishing territorial borders and in aggressive encounters with other loons. Males will also yodel if a predator is seen approaching the chicks, such as when an eagle flies overhead. Floatplanes also trigger yodel calls. The yodel is most frequently given during the nesting season. Yodeling males crouch flat to the water with their head and neck extended and the lower bill just over the water.

The Hoot

The hoot is a soft note, given intimately among loons. It is a one note contact call between birds. Adults will hoot to each other, and parents will hoot to chicks, enabling them to keep in touch on the whereabouts of each other. It is specifically used when a loon is maintaining close contact with another family member or a small flock. So powerful is the instinct to locate the hoot of their young, adult loons are easily captured at night by researchers imitating a young loon hooting. I’ve been with loon researchers at midnight when adult loons have swum up to our boat to be temporarily captured in large salmon nets. In fact, an imitation chick hoot call is the most effective technique used by researchers to capture loons to draw blood for mercury analysis. (Sadly, our loon population has some of the highest levels of mercury in the country. Mercury is carried into Maine on prevailing west to east winds, known as atmospheric deposition. Maine’s mercury sources originate out of state, mostly from coal fired electric power plants in the Midwestern U.S., and from industrial incinerators in the Northeastern U.S.) Hoot calls are also commonly heard among loon social gatherings after the nesting season when “rafts” of loons can be seen on lakes. The hoot is the most frequently given winter call when loons are largely silent in the ocean waters of the Gulf of Maine.

Enjoy listening to loons but please give them ample space when approaching them on the water. We recreate on Megunticook and many other Maine lakes. For loons, though, the lakes are their homes.

Ron Joseph of Camden is a retired Maine wildlife biologist.