Are loons on thin ice with climate change? An outbreak of winter loon rescues in the Northeast

In the Northeast, after experiencing a body molt, Common Loons (Gavia immer) typically migrate in the fall (mid-October through late November) in response to shortening day length, to winter along the mid-and north Atlantic... [ view full abstract ]

In the Northeast, after experiencing a body molt, Common Loons (Gavia immer) typically migrate in the fall (mid-October through late November) in response to shortening day length, to winter along the mid-and north Atlantic coast. In late winter, they undergo a complete remigial molt prior to returning to the breeding lakes, and so, are unable to fly for approximately a month until their flight feathers grown in. Hatch year loons migrate to the coast after the adults, as their natal lakes freeze up, and do not molt into adult plumage until at least 2-3 years old.
Winter, 2016 was mild until early January, when temperatures rapidly dropped below zero oF. In January, 16 loons in NH, NY, and VT were reported needing rescue after being “iced-in” or landing on a road. Temperatures fluctuated in subsequent weeks, and in February, an additional 10 loons were reported being “iced-in” on the VT side of Lake Champlain. Of the 26 birds, 5 died or were predated prior to rescue, 3 were treated at rehabilitation centers (2 for underlying lead toxicity and 1 for injuries related to fishing line entanglement), and 2 had landed on a road and were released. The remaining 16 loons were all released; 2 were hatch year birds who hadn’t migrated, and at least 5 others had molted their flight feathers prior to below-zero temperatures causing the lakes to freeze, and were incapable of flight. Similarly, in 2007, 20 loons in NH had failed to migrate prior to a late winter freeze-up, and required rescue because they had molted their flight feathers and couldn’t fly. It is expected that the incidence of Northeastern loons being iced-in due to loss of flight feathers will increase with later freeze-up dates as climate change causes more variable winters in the future.