Lake Learning column: Summer will arrive eventually; the loons are back
Will this winter ever end? Even though the ice is reluctant to leave the lakes and we have been getting weekly snow storms, there are still some undeniable signs of spring. Last week I heard my first loon call, and it gave me goose bumps. Summer will arrive eventually! There's something about hearing loons echoing over the water that is so Minnesotan. On March 13, 1961, Governor Elmer L. Andersen signed the legislation that adopted the common loon (Gavia immer) the official state bird of the State of Minnesota.
I have seen loons in Detroit, Pelican and Muskrat Lakes so far this year. So where do loons go in the winter, and why are they found on some lakes but not others? These are the questions I'll address this week.
Loons are migratory birds, and since our lakes are ice-covered in the winter they are not able to stay here and find food. Loons are diving birds and eat fish. They eat everything from panfish and perch to suckers, bullheads, and minnows. They also may eat frogs, leeches, crayfish, mollusks, salamanders, amphipods, and insects.
In September, the loons leave us to spend the winter on the southeast coast, from North Carolina to Florida along the Gulf of Mexico.
Loons are unique birds, and can dive more than 200 feet below the surface to find food. Since they are built for swimming, they actually cannot walk well on land. Their legs are too far back on their body. Loons can also live up to 30 years.
Minnesota has the largest summer population of loons in the lower 48 states, and approximately three quarters of the common loons in the Midwest. The DNR estimates the total Minnesota Loon population to be around 12,000 adults. The DNR has a Loon Monitoring Program, and each year volunteers collect information on common loon numbers on more than 600 lakes distributed among six regions, or "index areas" of the state. One of the index areas is central Becker County, and loon populations have slightly increased in this area over the past 13 years. In this Becker study area, there are an estimated 1.6-2.5 adult loons per 100 acres of lake. In the Otter Tail area, the loon population has not changed, and there are an estimated 1.3-1.9 loons per 100 acres of lake.
So what type of lakes do loons prefer for their home? Since loons are diving birds that use their eyesight to capture their food, they need clear water and healthy fish populations. This is why they are used as an indicator for lake water quality. Also, loons only nest on undisturbed shorelines or islands with plenty of natural vegetation. They need tall shoreline vegetation for protection of their young. Larger lakes and longer shoreline are associated with more loons. Because loons nest at the waters' edge, they are easily disturbed by excessive boat traffic and wakes, and are displaced by human residential activity. If you are out boating and see a loon, keep some distance between you and the loon so you do not disturb it.
One of the main threats to loon survival is lead sinkers. When lead sinkers are lost during fishing and sink to the bottom of the lake, they are inadvertently swallowed by loons and other diving birds. These birds routinely swallow small pebbles from the bottom of the lake to aid in digestion. If they swallow lead they get lead poisoning, which can cause death. A loon with lead poisoning will act strangely. It may droop, fly poorly or have crash landings. It only takes one lead sinker to poison a loon.
There are many non-toxic types of sinkers available now, so before opening fishing weekend, take a look through your tackle box and dispose of all your lead.
To read more about loons, you can visit the DNR website: http://www.dnr.state.mn.us/birds/loons/index.html.
Until next week, enjoy the lakes!
(Moriya Rufer is the Lakes Monitoring Program Coordinator for RMB Environmental Laboratories in Detroit Lakes, 218-846-1465, email@example.com.)