Does climate change threaten the common loon in Wisconsin?

Michael W. Meyer is the owner of NOVA Ecological Services and a retired wildlife researcher at the Wisconsin Department of Natural Resources.

Who are you/what is your role?

I am a former WICCI Wildlife Working Group co-chair (2007–2014) and a retired wildlife toxicology research scientist in the Wisconsin Department of Natural Resources, Bureau of Research and Science Services. I have spent 25 years studying loons from many different angles.

Currently I own an environmental consulting company, NOVA Ecological Services, in Manitowish Waters, Wisconsin, and serve on the Wisconsin Green Fire Board and Climate Change Working Group. Wisconsin Green Fire is a non-profit organization whose mission is to promote science-based natural resource policy in Wisconsin.

What has been happening with the common loon?

Loon populations have been slowly rebounding in Wisconsin the past 30 years, but there is some evidence this trend is changing. Survey results from the Wisconsin LoonWatch program have shown the statewide Wisconsin loon population had been slowly increasing from 1985-2015 but recent research in north-central Wisconsin by Dr. Walter Piper and his research crew from Chapman University provide evidence the population may be at a tipping point and may soon begin to decline due to lower reproductive success and reduced adult loon survival.

While loons historically nested in southern Wisconsin into northern Illinois, current survey results find few loons nesting south of central Wisconsin. Kevin Kenow, with the United States Geological Survey in La Crosse, has documented the historic and current range of common loons in Wisconsin. He quantified an approximate 200-mile recession of loon breeding range since pre-settlement times, likely due to changes in land use, increased disturbance, and nutrient run-off to lakes.

With the loon, we have always suspected that climate could contribute to their range recession into the future as Wisconsin, Minnesota, and Michigan are at the southern extent of the range in the Upper Midwest.

Loons have pretty prescribed nesting habitat requirements, and factors that influence nesting habitat have the potential to alter reproductive performance. When possible, loons prefer to nest offshore, away from mammalian predators, but always close to the water’s edge. This is because they are relatively immobile on land, they cannot walk or stand upright, thus search for a nest site with a quick escape route to water when threatened by predators or other disturbance.

During the nesting period, they are also vulnerable to extreme precipitation events and drought. Inundation in the spring can flood nests and droughts can make some traditional nesting sites unusable because of the need to be at the water’s edge — when lake levels are low some nesting sites are high and dry and abandoned for nesting. In certain years, blackfly infestations on the nest can cause wholesale abandonment of the nests, up to fifty percent abandonment in bad years. Whether or not the intensity of blackfly infestations can be attributed to changes in climate is not known. Also, Common loons are “cold-adapted,” residing in cool to cold waters much of the year. As Wisconsin lake waters warm (as has been documented), it is not known whether there is an upper level of water temperature loons can tolerate.

Another risk to loons on the breeding ground is lead toxicity — upward of 20 percent of adult loon mortality in Minnesota and Wisconsin have been attributed to ingestion of lead fishing tackle or entanglement with fishing line and lures.

Away from the breeding grounds, Botulism E. toxicity has caused large scale adult mortality, most recently 2006-2012 on Lake Michigan and Lake Erie. Migrating loons from the Upper Midwest spend several weeks in the fall staging in northern Lake Michigan. While there, Kevin Kenow and colleagues found they were ingesting large quantities of round gobies, an invasive fish, which had accumulated botulism toxin from ingesting quagga and zebra mussels, also invasive species. The mussels filter feed and ingest toxic algae byproducts that formed along the shores of Lake Michigan.

Hundreds of adult loons were lost during those years of very warm summers with low Great Lakes water levels, which favor algae overgrowth. That type of climatic condition will probably continue to cause these episodic mortality events. The loss of adult loons can have significant population effects as individuals can have a life span of over 20 years.

Other risks for Wisconsin loons occur on their wintering grounds. Wisconsin loons primarily winter offshore in the Gulf of Mexico, most from Gulf Shores, Alabama, south to Tampa Bay, Florida. Those wintering grounds are also threatened by toxic algae blooms and are near the Deepwater Horizon oil well blowout where many loons were lost to oiling ten years ago. So, Wisconsin loons face threats not only on the breeding grounds, but throughout their annual migration cycle

What is being done to help? 

To me, the most impactful ways to help loons in Wisconsin is to protect existing nesting habitat, increase nesting habitat through artificial nest platforms, getting lead fishing tackle out of fishermen’s tackle boxes (there are alternatives!), and supporting wildlife rehabilitation efforts. The loons take readily to artificial nesting platforms when placed in appropriate locations (check with LoonWatch for guidance) and they can help maintain loon breeding on lakes that are becoming developed. Outreach programs should focus on making lake users aware that we are losing loons because of lead fish tackle ingestion (up to 20 percent of loon mortality in the Upper Midwest is due to lead poisoning), entanglement with fishing line and lures, and trauma from boating accidents. Again, this education has been a primary focus of LoonWatch at Northland College through the years.

The Raptor Rehabilitation Center in Antigo, Wild Instincts in Rhinelander, and the Northwoods Wildlife Center in Minocqua have been active in rehabilitating injured loons in the Northern Highlands Lake District. There are other wildlife rehabbers as well working throughout the Upper Midwest. Supporting their efforts financially would be a great way for you to get involved in loon conservation as one adult loon saved can lead to many loon chicks produced over the years.

Do you have hope for the future of loons in Wisconsin? 

Yes, unless there is some climate variable that is insurmountable. Some work needs to be done to continue conserving and improving nesting habitat, reducing human-caused mortality such as exposure to lead and accidental trauma, and we need to continue to do education and outreach and rehabilitation. Because Wisconsin loons have such a built-in fan club there are a lot of people that go out of their way to make certain that the loons on their lake are protected. Many Wisconsin citizens are already motivated to conserve the common loon.

The loon is often described as the poster child for wild Northern Wisconsin lakes and “keeping the North the North.” Some consider the loons a sentinel species for how well the northern lakes are doing. Because they’re so vulnerable to human disturbance like shoreline development and boating behavior, it’s important to try to see things like that through the loon’s eyes. The wellbeing of the loon is, in a sense, also part of the wellbeing of us all.

Learn More

• Migration patterns and wintering distribution of common loons breeding in the Upper Midwest
• USGS | Science Explorer-Common loons
• The Loon Project Plunging floater survival causes cryptic population decline in the Common loon
• Northland College | LoonWatch
• Raptor Rehabilitation Center in Antigo
• Wild Instincts in Rhinelander
• Northwoods Wildlife Center

The views and opinions expressed in this interview are those of the authors and do not represent official policy or position of the University of Wisconsin-Madison or the Wisconsin Initiative on Climate Change Impacts.