Tuesday, June 26, 2012

Loon Language

The mournful wail of a common loon echoes across the glassy water. From a neighboring lake, another loon replies with the same smooth cry. The loons are keeping track of one another, maybe as neighbors, maybe as mates, maybe as rivals.

Sometimes the still night air is pierced by the maniacal laughing yodels of two male loons. This signifies a battle over territory. Home territory means a lot to loons. The longer a male resides in the same territory, the greater his chance of raising chicks to adulthood. The resident male will fight to the death if necessary to defend his island, lake or bay. Even if the invading male wins, the resident female will stay on the territory with the new male.

An invading loon, looking for his own place to raise a family, will fly over an occupied territory and first give the wavering tremolo flight call. If the resident male is willing to fight for the prime real estate, he will reply with a yodel. The invading loon can tell by the lowest note in the tremolo approximately how big the defender is, and use this information to decide whether a fight is in his favor or not. If he chooses to fight, the invader replies with his own unique yodel. Loons can tell each other apart by their calls, and even third-graders can tell loons apart by looking at sonograms of their yodels!

The male chooses a nest site hidden in tall vegetation near the water. The female builds the nest by pulling plants around her body to form a low bowl. After that, they share the parenting duties 50/50. Alternating incubating and eating, they wait for 26-31 days until the two eggs hatch a day apart. The parents communicate with the chicks using a soft, short “hoot.” If eagles are present, the parents may give a version of the tremolo flight call. Bald eagles are a known predator of loons, and the alarm call tells the chicks to “DIVE NOW!”

Eagles are not the only danger for loon chicks. Gulls are also nest raiders. In the Boundary Waters Canoe Area, fish guts left by anglers allowed the population of gulls to increase. More gulls meant fewer loons – and now the Minnesota DNR and others encourage anglers to dispose of fish remains in the woods, away from aerial scavengers.

Many anglers enjoy watching loons on their favorite lakes, while others may see the loons as competition. Loons mostly eat smaller fish like yellow perch, and do not have a significant impact on game fish. Humans can negatively affect loons in several ways, though. Excessive wakes near nesting sites can knock eggs in to the water. Snagged fishhooks and line can entangle many kinds of wildlife. Lead sinkers are also a major issue.

Loons do not have teeth, and neither do they have a mechanism like owls to cough up pellets of undigested hard parts. The fish bones and fish scales have to go all the way through their digestive system. To achieve that, loons have incredibly strong gizzards, and they ingest small, round rocks to help pulverize their food. Unfortunately, lead sinkers look like good gizzard stones. Many loons and other wildlife die a prolonged and painful death by lead poisoning every year.

Lead is not the only toxin we introduce into lakes. Every year around the Fourth of July, and sometimes throughout the summer, we sprinkle a wide assortment of toxic elements into the lakes. We are usually so awed by the spectacle of the beautiful fireworks reflecting on the water that we do not think about the morning after. The noise of the explosion itself can frighten loons of their nests – leaving the eggs open to predators. The plastic casings of the fireworks can sneak into the food chain, causing malnutrition problems. Plus, those interesting, but sometimes carcinogenic elements in the fireworks – the ones that make the cool colors when they burn – can end up in the lake.

This time of year we can see days-old chicks so fluffy they pop up like corks, and awkward teenage chicks just learning to dive. Some loons are still incubating eggs – trying to nest for a second or third time after their first attempts were foiled by thunderstorms, raccoon raids, or other bad luck. Please try not to make their tough parenting job any harder!

You can see adult and baby loons and learn more about their amazing features every Thursday morning from July through September on the Loon Pontoon tours I host on Lake Namakagon. Last summer we watched two chicks grow up week by week until they migrated south for the winter!

Loons are icons of our beloved Northwoods. Their sight and songs bring joy to many residents and visitors of the area. As you enjoy their home, please consider how your behavior can affect them. Thanks!

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