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Facts about Loons

Conservation

Q. What are the threats to loons today?

A.
Human activities are causing loons to disappear from many lakes. Traditional nesting areas have been destroyed by development of shorelines and islands for summer homes, campgrounds, and marinas. Being disturbed by tourists, pets, motorboats, jet skis, etc., especially during sensitive nesting and chick-rearing periods, can reduce or wipe out loon populations. Pollution of lakes where loons nest can lead to build-up of toxins in eggs and young. Water pollution can also harm food supplies for chicks and adults--pesticide run-off, mercury, and lead are some of the worst. And even today people find dead loons with pellets or bullets in their bodies. One researcher found that 32% of loon cadavers he autopsied had embedded pellets.

Q. If a loon were trying to elude a motorboat, would it be more likely to dive or to sink into the water? How about if it were trying to elude a distant Bald Eagle?

A.
When a loon wants to get away in a hurry, to avoid a motorboat or other fast danger, it dives fast! To avoid a distant Bald Eagle, and to escape detection in the first place while the eagle is still far away, the loon will slowly sink into the water, without leaving a ripple.

Q. How does mercury from the atmosphere end up in a loon?

A.
Most, if not all, of the mercury entering Earth's surface waters comes from the atmosphere. It gets into rivers, lakes and streams when it rains. Once in the water, it gets in the food chain.


Q. What kinds and sizes of fish are worst for mercury contamination?

A.
Large fish like walleye concentrate the mercury because they are high on the food chain. The larger amount of mercury in larger fish comes from the many minnows they've eaten, all of which have also taken in mercury.


Q. What are some effects of mercury poisoning on loons?

A.
Adult loons can pass mercury on to the egg, and the chick will have higher mercury levels. The effect is not eggshell thinning, as with DDT, but is lack of motor coordination in chicks because the mercury affects their nervous system.


Q. How widespread is mercury pollution in North America?

A.
Dave Evers reports: "Substantial mercury pollution of lakes and streams already exists on our continent. Global mercury levels are now 3 to 4 times higher than natural background conditions. Recently, studies have found elevated levels of methylmercury in the body burden of loons. Although average whole blood mercury concentrations for Minnesota and Wisconsin loons are not as high as those found in New England and the Canadian Maritimes, they are double Alaskan samples that represent background levels. These blood studies show that loons are exposed to too much mercury."


Q. Does the mercury in lakes ever "go away," or must it forever be part of the food chain, ending up in fish and loons?

A.
Dave Evers says, "Mercury can settle out into bottom sediments and become less available to the food chain. In contrast, if lakes become acidic, mercury that's in the bottom sediments can actually be dissolved into the water."


Q. What methods are available to remove mercury from lakes?

A.
There are no current methods used on lakes.


Q. How do scientists study mercury levels in loons?

A.
They take samples of the feathers and blood. These samples show how much mercury is stored in loons' bodies. As more samples are collected, scientists hope to have a clearer picture of how mercury and the loons' health are related. Read more on the Journey North Website.


Q. What can studying a loon's feathers tell about mercury in its body?

A.
Scientists Joe Kaplan and Keren Tischler are working to figure out when and where mercury (Hg) gets into the loons' blood. Because feathers are grown at a known time of year, they are like a snapshot in time. "Using feather mercury values from hatch year loons found in the winter, we can hopefully extrapolate what the blood mercury level was at the time the bird fledged. Mercury tested in these feathers indicates the levels the young loon had on its natal lake in the north. Then, with a new blood sample, we can determine changes in the amount of mercury found in blood since the bird has been on the ocean. An additional bonus is that many of the young loons have already begun replacing feathers, so we can compare old and new feathers and determine the changes in mercury over the last 4-5 months. We will do the same thing with 2 to 3-year-old loons that have spent at least a year on the ocean. Eventually Joe and Kerin would like to develop an exposure model of mercury that can account for year-round accumulation of mercury from both the summer and winter territories.


Q. Does intake of mercury cause loons to live shorter lives?

A.
There have been cases of loon die-offs with mercury poisoning suspected as the cause, but the worst problem from mercury is reducing loon reproduction. Dave Evers repies: "Loons have reproductive FAILURE if they eat fish with higher than .4 parts per million. Reproduction is impaired when the fish have .3 parts per million. (Reproductive failure means the young do not survive.)"


Q. Are food eaten in the summer more likely to give loons mercury than fish they eat on the wintering grounds?

A.
Dave Evers says, "We believe that fish eaten in the summer are the problem. Here's why: Feathers can be tested for mercury, and feathers that have grown during the wintertime (on the wintering grounds, before migration) do not seem to contain high mercury levels."


Q. Why is research on mercury contamination of loons important for human health?

A.
Since loons are so high up in the food chain they may also be a very good indicator of how mercury could affect humans. Since it's estimated that 95% of human mercury exposure is from eating fish, these long-them studies are important to humans. In fact, human consumption of fish is not recommended on many lakes due to mercury pollution. In the state of Minnesota for example, 1/3 of the state's 10,000 lakes have mercury advisories, cautioning people too not eat too many fish from those lakes.


Q. What factors make loons good "early warning" indicators for human health?

A.
Common Loons are ideal indicators for human health because we can study individual birds over the long-term. This is because loons (1) can be easily captured and recaptured, (2) are easy to monitor throughout the day, (3) show fidelity to a breeding territory, (4) are long-lived and (5) are highly sensitive to the bioaccumulation of methylmercury.

Q. What does the term bioaccumulate mean?

A.
It refers to a substance building up, or accumulating, in living organisms.

Q. Could someone have a pet loon?

A.
Absolutely not! It is against laws in the U.S. and Canada to have loons for pets. Dave Evers points out that there have been a few people who have kept loons in captivity, sometimes before they were protected, and a few with research permits. Mostly loons are "taken care of" at animal rehabilitation centers if they have been injured or are sick. These birds are treated and the goal is to release them to the wild again. The Minnesota Zoo has had the most intensive loon rearing program. They raised several loon chicks but were not able to keep the young birds alive to adulthood. Loons do not appear to do well in captivity. There are also a few stories of people who have "tamed " loons on their lake. This is an unusual situation and in the few instances it has occurred the loons were not tame enough to be touched.


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