Date: 10/3/26 5:14 am From: Peter Saracino <petersaracino...> Subject: [GeneseeBirds-L] Fascinating facts about loon migration
Courtesy the folks at the Vermont Center for Ecostudies;
Loons Take Their Leave
*By Eric Hanson*
Those lucky enough to still be spending time on their favorite Vermont
lakes—and submitting surveys
<https://vtecostudies.org/what-we-do/projects/loon-conservation/loon-volunteer-materials-2>,
thank you—may have noticed the disappearance of their resident adult loons,
even with chicks still around. Or you might observe congregations of up to
18 loons on larger lakes such as Caspian Lake or Norton Pond.
So, when do loons take to the skies? To help answer that question, I’ll
refer to Lee Attix’s work from 2013 to 2017 on loon migration timing for
the Biodiversity Research Institute, which he shared with me some years
back. As reported in Northern Woodlands
<https://northernwoodlands.org/pdf/tos-loon-chicks.pdf>, starting in
September, Lee checked in on 32 banded loon pairs in Maine and New
Hampshire twice a week until late November. He found a lot of variability
in the timing of loon departures, but also some general trends.
Some adults start to move or even leave in September, while others stick
around until late November. Chicks tend to depart in late October and
November, but like the adults, some will leave in late September. Others
never seem to get that migration restlessness (referred to as *zugunruhe*
in textbooks) and are still on the water when ice starts to form. Some of
his findings include:
- Adults left separately; 62% of the time the female departed first.
- Some adults appeared to leave in early September. However, when an
adult leaves his or her breeding lake, it’s often to spend time on a nearby
pond and not to migrate directly to the ocean. There is a chance some of
these early departing adults returned to the territory after being gone for
days or weeks.
- The youngest chick at the time of the first adult’s departure in early
September was eight weeks old.
- The average age of juveniles—fully feathered and ready to fly—when the
last adult departed was 17 weeks old.
- In two-chick clutches, one juvenile occasionally left before the
second adult.
- On average, the last juvenile left three days after the last adult.
There were three cases where the juvenile left 22 to 37 days after the last
adult. The departure of the last adult might be a signal for the juvenile
to also leave, but not always.
Most New England loons spend the winter off the Northeast coast, with a
short migration period of only one to two days. Juveniles figure out how to
reach the ocean on their own and likely take a much longer time getting
there. A 2009 satellite telemetry study
<https://www.usgs.gov/publications/migration-patterns-and-wintering-range-common-loons-breeding-northeastern-united> followed a lone New York juvenile as it left the Adirondacks in late
November and took 56 days to puddle jump from lake to lake, eventually
reaching Long Island Sound in January.
Juveniles that reach their second year are considered immature a.k.a.
subadult <https://vtecostudies.org/blog/loons-the-early-years> birds, and
they usually spend several years on the ocean before returning to their
natal lake region as sexually mature individuals.
Loons from the central part of North America have a lot farther to fly than
New England’s loons! They will overwinter along mid-Atlantic and
southeastern coasts and the Gulf of Mexico. One study that followed two
loons from Saskatchewan
<https://bioone.org/journals/waterbirds/volume-37/issue-sp1/063.037.sp107/Common-Loons-Gavia-immer-Wintering-off-the-Louisiana-Coast-Tracked/10.1675/063.037.sp107.full> revealed that one individual migrated to Lake Michigan and straight down to
the Gulf of Mexico, while the other loon flew to the same location in the
Gulf via Lake Erie, the Chesapeake Bay, and across the Florida Panhandle.
How did they choose which route to take? We don’t really know, but once a
loon learns a route, they stick with it for years to come.
After spending the winter eating seafood on the ocean, loons will return to
northern, forested, freshwater lakes and ponds in the spring, usually in
April or early May. The magic of migration in all animals is fascinating:
What initiates it, and how do species find their way back to the same lake
or forest stand in spring? The sun, stars, Earth’s magnetic field, learned
behavior, and genetics are several of the myriad factors that influence
these amazing journeys.
