Loons encounter unlikely threat: ice

Missed migration cues cause some birds to get stuck

By Cayte Bosler 

The call of the loon holds great meaning for many in the Adirondacks. 

To some, it is an ethereal sound like a lurking spirit. Or it harks back to childhood memories. Or perhaps it is a symbol for the wilderness as a whole evoking reverence and mystery. Their iconic yodel can be all of those things, and more.

But these aquatic birds, Gavia immer, so tied to the Adirondacks face increasing threats like unprecedented winter conditions and sudden storm floods, which can disturb their migrations and nests. Recent loon rescues have underscored the importance to conservationists for strategic plans needed to support them in the coming years. 

Iced in

In early March, staff from the Adirondack Center for Loon Conservation (ACLC) took part in a rescue of five common loons that were the victims of an “ice-in” on Lake Champlain. Rescuers found them stuck in a small hole where they were vulnerable to exhaustion and predation and brought them to safety. 

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Before lakes freeze over in December and early January, breeding loons typically depart for either the Atlantic coast or southern reservoirs. Prompted by seasonal cues such as slowly encroaching frozen water, they leave before the ice can trap them. The last decade or so, however, has brought milder winters where the larger lakes are more likely to stay open, enticing loons to stick around longer.

“Loons that are migrating through the Adirondacks from farther north or loons who breed in the Adirondacks may see the open water on the larger lakes and decide to stay there instead of flying farther to the coast,” said Nina Schoch, executive director of the loon center. Migration requires loons to fly nonstop for over eight hours and unlike many bird species, they didn’t evolve to glide. They depend on their strong shoulder muscles for every inch. “It takes a lot of effort, they need to find open water where they can feed and gain more energy before flying again,”  Schoch said.

According to ice records, some of which are maintained by Brendan Wiltse and Curt Stager of Paul Smith’s College, lakes are freezing less frequently than in the past. “This is a pattern we are seeing on lakes across the northern hemisphere,” Wiltse explained. “The Lake Champlain Basin program predicts that if this trend continues the lake will only freeze once per decade by 2050.” 

The loons drop to rest or stay later on lakes like Champlain and George, taking advantage of the milder temperatures, when suddenly what seemed an opportunity to restore turns into a desperate situation. Cold snaps plunge temperatures below zero and the lakes quickly harden with ice. 

This is life-threatening to the common loon for at least two reasons. One is that they molt their flight feathers in the winter and are flightless for up to a month –  meaning if they miss their migration window and molt before they reach the coast then they are stuck when the ice hits. This is known by ornithologists as a “molt-migration mismatch.” The other is that even if equipped to fly, the species requires a “runway,” at least a quarter of a mile of water to gain the speed necessary to propel their dense bodies into the air. 

A growing problem

Nine loons needed intervention from being iced in this winter, a record for the center. It’s not only the Adirondacks seeing a surge in this problem — throughout New York, New Hampshire and Vermont all have had an increase in the number of  such rescues over the last 10 years, according to Schoch. 

Schoch has been studying Adirondack loons since the late 1990’s and recalls first rescuing iced-in loons in February 2013, after an ice fisherman reported  five in a hole on Lake George. “Prior to that, I only remember hearing reports of the occasional iced-in loon,” she said.

Now, loon rescues are expected to become more frequent, even annual events, and the center has prepared management techniques to reflect this. 

“Our plan is to establish and coordinate several trained loon rescue teams throughout the Adirondacks, who will be available to respond to a distressed loon within a few hours,” Schoch said. The work will be coordinated with the state Department of Environmental Conservation and the SUNY College of Environmental Science and Forestry’s  Adirondack Ecological Center in Newcomb, where a loon rehabilitation facility will be established. “That will enable us to conduct a variety of diagnostic analyses and treat and rehabilitate the birds if needed prior to release,” Schoch said.

This work is made possible in part by almost $800,000 recently granted to the center from the Bouchard Barge B-120 oil spill settlement which in 2003 killed more than 500 loons when the ecological disaster struck in Buzzards Bay off the coast of Massachusetts. 

Nesting sites at risk

In addition to the iced-in intervention, researchers anticipate loons being adversely affected by brash fluctuations in the aquatic ecosystem. “We are seeing an increase in precipitation in the region over the past century and climate models predict this trend will continue,” Wiltse said. “As well as an increase in periods of intense and heavy rainfall.” According to research done by Wiltse and Stager reconstructing hydroclimate variability over the past 1,600 years, the region may see bigger swings between wet and dry conditions under a warmer climate. 

Loon nests are vulnerable to sudden shifts in water levels. Strong storms with torrential rain, occurring with more frequency and intensity in the Adirondacks, can drown a nest within hours. “The loons float, but the eggs don’t,” said Jennifer Denny, communication and education coordinator for the loon center. “They tend to nest right at the level of the lake. They evolved to swim well, but not walk. With these intense rain events, they are less likely to have a robust population of chicks.” Surveys show that Adirondack loons typically lay 1-2 eggs per year.  “Because loons do not produce a lot of chicks each year, even one egg lost can affect the future of the population,” Denny said.

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The center’s next five-year management strategy includes nest rafts, signage, buoys and rope lines around the loon nest sites, Schoch said. The nest rafts have shown success in other regions experiencing similar problems. 

Paul Smith’s Adirondack Watershed Institute is working on building a lake level monitoring network to better understand how climate change is impacting lake levels moving forward.

Community-led efforts

“When you protect the loon, you protect the ecosystem,” Denny explained. “They are a biological indicator for Adirondack waterbodies.” In the past, sick loons alerted community members to toxic levels of mercury in the water due to atmospheric deposition. Methylmercury bioaccumulates in the birds’ bodies, acting as a neurotoxin. 

The center launched its Loon-Friendly Lake Certification Program which “promotes community-based environmental stewardship to better protect loons and their aquatic habitats” –  offering ways for the public to directly report threats and to take action in their backyards through citizen science initiatives. 

“People gravitate toward loons,” Denny said. “I think a lot of it has to do with past success addressing the mercury problem. Their comeback from that is representative of how people can change their act.” 

“They are such a part of the North Country experience,” Denny added. “If you ever hear them call at night, you associate it with good memories. They are important to people’s personal histories.”