Threats to Loons and Their Habitats
These paddlers were recorded by a nest camera on an Adirondack lake. Repeated disturbances like this can cause a loon to abandon its nest.
HUMAN DISTURBANCE
People can easily disturb incubating loons and cause them to abandon their nest. When out on a lake, especially during the spring and summer, please watch for nesting loons or loons with chicks. Remember that loons and other wildlife share the water with us; observing loon families and their behavior from a respectful distance (at least 100’) will benefit both humans and wildlife.
Disturbance of loons by other wildlife or humans can disrupt incubation and cause a nest to fail or be abandoned.
Some easy tips for loon watching:
Use binoculars or a camera with a long lens to watch loons
Follow the ‘Rule of Thumb’ - When you extend your arm in front of you with your thumb up, you should be able to completely cover the animal you are looking at. If any part of the animal is not covered by your thumb, you are too close. Please give them more space!
Learning loon behavior can help you distinguish if a bird is in distress or behaving in a normal manner. Adult loons will vigorously “penguin dance” on the water or call loudly to distract people or predators away from chicks or a nest. If you see this behavior, you are stressing them out and should leave the area.
Exploring the water on your motorboat or jetski? Chicks are not able to dive well, so sometimes they can’t move quickly enough to get away. Be conscientious of your surroundings, and keep your distance from loons. If your wake is making waves on the shoreline or small islands, please slow down so you don’t flood a nest.
Paddling? Stay at least 100 feet from the shoreline to avoid accidentally scaring a loon off its nest or disturbing loon families. If they are constantly moving away from you and tremoloing, you are too close for their comfort.
Visiting an island? Keep an eye out for a nesting loon! They are easily disturbed by people exploring or camping and may abandon a nest if people approach too closely for their comfort.
A black bear predating a loon nest, captured by a nest camera.
Adult loons can also be very aggressive towards each other, fighting fiercely to the point that they sometimes cause serious or fatal injuries to each other.
Wildlife Predation
Many animals prey on loon eggs, including crows, ravens, eagles, bears, gulls, and raccoons. Such opportunistic predators are more abundant near human houses or camps because they are attracted by garbage. Loon chicks are often killed by eagles, snapping turtles, large fish, and other loons.
Fishing line entanglement
The number of loons tangled in fishing line in the Adirondacks and the Northeast rises dramatically during the summer fishing season. Birds can eat fish that have broken a line and still have line or tackle attached.
If a loon swallows a fish that has line attached, it will fling the line around and around its head and bill in a futile effort to get it off, thus entangling itself even more. Fishing line often cuts into a loon’s mouth which can cause infection. Entanglement can also prevent loons from eating, and this can ultimately result in a prolonged and painful death for the loon.
Make sure to collect any fishing line that you find washed up on the beaches, and retrieve any broken line that you can. Our Fishing Line Recycling Program also provides resources for this threat.
Lead fishing tackle
Lead is toxic to animals and humans when eaten or inhaled. Loons, swans, herons, and other waterbirds, as well as eagles, die from lead poisoning after swallowing lead fishing tackle. These birds endure a slow death from lead poisoning as the tackle breaks down in its stomach.
There are several actions that increase the potential for lead poisoning. Anglers attach lead sinkers and jigs to fishing line to sink the hook, bait, or lure into the water. If the line breaks, the lead can be lost to the depths of the lake. Loons and other waterbirds are also exposed to lead if they eat a fish that has broken a line and still has a hook and lead tackle sinker attached.
Research by the Loon Preservation Committee and Dr. Mark Pokras of Tufts Wildlife Clinic found that lead poisoning from ingestion of lead sinkers and jigs accounts for a significant portion of the adult loons found dead in New Hampshire.
Luckily, this problem is easy to prevent! There are many nontoxic tackle options, including stainless steel, ceramic, and bismuth sinkers and jigs. Our Lead Tackle Buy-Back Program partners with local bait shops and allows you to trade in your lead tackle for non-lead tackle.
Climate Change and Water Level Fluctuation
Loons make their nests along the shoreline, often on islands or small mounds of vegetation. If the water level drops, the adults may abandon a nest because it is difficult for them to walk on land, especially if they have to climb uphill.
In a span of several hours, this nest was flooded during an intense early summer storm.
On the other hand, the incidence of torrential rain events during May and June has been increasing in the Adirondacks. Many inches of rain can fall in a matter of a day or two in such storms, and the rising water level can flood nests. As a result, the eggs get chilled and fail to hatch.
Water level fluctuations also causes stirring of the sediments at the bottom of a water body. This results in increased turbidity (low clarity) of the water as well as disturbance of contaminants that have deposited in the lakebed.
Shoreline Development
In the Adirondack Park and may other places in the Northeast, some of the highest rates of development are occurring along the shorelines of lakes. Shoreline development can cause a variety of ecological changes that affect loons, including fewer potential nesting sites, limited high-quality territories, increased numbers of scavenging predators, and increased recreational activity.
Threats on the Coast
Botulism
Type E Botulism (Clostridium botulinum) has caused massive and devastating annual epidemics of fish-eating birds on the Great Lakes during fall migration. Since the early 2000s, an annual outbreak of Type E botulism on Lakes Erie and Ontario has killed thousands of fish and birds, including many Common Loons migrating through the lakes.
Loons and other waterbirds contract botulism, which grows under anaerobic conditions, by eating infected fish, such as alewives and round gobies. These invasive species were introduced by cargo vessels traveling through the Great Lakes. The infected fish acquire the botulism toxin by feeding on another invasive - quagga mussels. This species concentrates the bacteria that produce the botulism toxin as the lake warms up during the late summer.
Within hours of eating a contaminated fish, a bird will experience weakness, inability to fly, respiratory distress, and paralysis. Most affected birds drown due to not being able to hold their head above water. Scientists collect the birds that have washed up along the beach to learn more about how the contaminant affects each species.
Oil Spills
The ecological price of a single marine or inland oil spill is immense - as evident by the many immediate and long-term injurious effects to the ecosystem and its inhabitants. Common Loons and many other species are extremely vulnerable to the toxic effects of oil. Accidents occurring during spring and fall migration in loon staging areas can be especially devastating to regional populations. Federal, regional and local organizations deploy trained response teams and use a variety of management strategies to assess and minimize the impacts of an oil spill on habitat and wildlife.
Gill-Net Fishing
Loons are one of the many “by-catch” species that are accidentally caught in commercial gill-nets set along the coast. It is likely that many loons die annually after they get entangled in fishing nets.