Loons are the quintessential symbol of wilderness. Just watch any TV show or movie that has a “wilderness” scene and you will hear loon calls in the soundtrack (even if it is in the desert). A stroll through any gift shop in the Adirondacks, Canada or Maine proves that they are probably the number one animal associated with the outdoors (competing only with moose and bears). There is nothing quite like the mournful wail of a loon floating through the night air as you lie in the dark trying to sleep. It is easy to see how people might once have associated them with unhappy or restless spirits.
Today loons might indeed be considered unhappy spirits because their future isn’t looking too bright. We usually hear about animals rushing towards the brink of extinction because of habitat loss, and while this may also apply to loons, the big concern these days is toxins, which are reducing their productivity. To be more precise, we are talking about mercury and its biproducts. For nineteen years the Wildlife Conservation Society, the BioDiversity Institute, and others, have been studying loons and the effect mercury emissions have had on their reproductive rates, and the picture is pretty grim.
Being at the top of the food chain, loons are ultimate repositories of toxins because of a process called biomagnification. Let’s say a plant accumulates one unit of toxin, perhaps absorbing it through its roots. An herbivore comes along and eats several of those plants, its body adding one unit of toxin for every plant it eats. For argument’s sake, we’ll say it eats ten plants, so now it has ten units of toxin. Next, a predator comes along eats ten of these herbivores; it now has 100 units of toxin in its body. Another predator eats ten of those predators and it gets 1000 units of toxin. This is biomagnification and, as you can see, it adds up pretty quickly. We add to this bioaccumulation, which is when the body acquires more of a toxin than it can eliminate. The result: toxin overload.
The toxin in question here is methylmercury (MeHg). MeHg comes to us via coal-burning power plants, incinerators (which is why you should recycle your batteries instead of tossing them in with the rest of your trash), and some forms of industry. In these instances, mercury (Hg0 – the “0” is a superscripted zero, not an “O”, which would be “Oxygen”) is released from the smokestacks. It could fall back to earth as a dry deposition and remain Hg0, or it could mix with water in the atmosphere and fall to earth as a wet deposition (rain, snow), Hg2+ (the “2+” is also superscripted). If this wet deposition gets into environments where there is a lack of oxygen (wetlands, saturated soils, lake bottoms), microbes start working on it in process known as methylation, converting it into methylmercury. This is the stuff that gets into the food chains and is deadly to those that ingest it. Why? Because MeHg is a neurotoxin. This is why there are limits on the number of fish it is safe for you to catch and eat. And it is why pregnant women are strongly cautioned to avoid eating fresh fish from Adirondack lakes.
Loons (and other wildlife) cannot read the fishing warnings put out by the EPA, so they blithely go along eating fish and accumulating MeHg in their bodies, and the results are not good. The WCS (et al) data show that loons with high levels of MeHg in their bodies are not spending enough time at their nests, which means their eggs are likely to chill or be eaten by predators. Affected loon pairs are fledging 41% fewer offspring than unaffected pairs. Additionally, the MeHg makes the birds sluggish and thus unable to catch enough fish to feed themselves and their young. Adult birds have also been shown to have malformed flight feathers, which likely affect their ability to fly and, therefore, migrate.
So where does the volunteering bit come in?
Every year the Wildlife Conservation Society asks folks who live in the Adirondacks to help them conduct a survey of loon populations within the Blue Line. They are especially interested in assessing the status of breeding birds.
This year the Annual Adirondack Loon Census is scheduled for Saturday, July 18th, from 8:00 AM to 9:00 AM. All you need is a boat and a lake (or pond). If you go to www.wcs.org/adirondacklooncensus you will find all the details, including the Census Lake Selection Table. You’ll want to pick a lake (or pond) that no one else has selected. Then you let the folks at WCS know which one you’ve picked ([email protected] or 518-891-8872). Give them your name, address, phone number, the name of the lake, and the county and township where the lake is located. They will send you a census form to fill out. What they are looking for is the presence of loons on these bodies of water.
If you sign up, please remember to respect the loons’ privacy. These birds get antsy if people (you are a predator as far as they are concerned) get too close. Some birds will even abandon their nests if they feel threatened enough. Because they are pretty showy birds and easy enough to identify, you can readily observe and count them from a safe distance.
Photo: Dr. Nina Schoch, 2002