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Midwest Science Podcast Series
“Unraveling Mysteries of the Common Loon”
Welcome to an episode of Midwest Science brought to you by the U.S. Geological Survey and the Upper Midwest Environmental Sciences Center.
I’m Randy Hines.
The Common Loon, a majestic diving waterbird, is a symbol of northern lakes and wild places. Breeding adults are readily identified by their black head and checkered black-and-white upper back.
At a population of more than 30,000 adult loons in the U.S., about half of these reside during the breeding season in the Great Lakes states of Minnesota, Wisconsin, and Michigan.
Because loons are long lived, and feed primarily on fish and other aquatic life, they are at risk for contaminant exposure (such as mercury), susceptible to oil spills, red tide (a harmful marine algal bloom), avian botulism, and predation from bald eagles and others.
Loons fulfill a role as a sentinel species, alerting us to issues that occur in aquatic ecosystems and other fish-eating waterbirds. Scientists often use the effects on wildlife as a sentinel for human health.
One USGS scientist, Kevin Kenow, is studying loons using modern technology to provide insights into the life history of this migratory bird for conservation planning.
“We’re collecting information on migratory movements of common loons breeding in the upper Midwest, identifying their staging areas during migration and wintering areas, and also collecting information on dive behavior to look at foraging patterns of the birds during migration and on the wintering grounds.”
In order to study a migratory bird, field work and modern technology are combined to gather insight on loon habits and movements.
“We have a couple of opportunities to capture loons on the breeding grounds. They are most vulnerable during mid-summer, when they are with chicks; and the adults are very protective of those chicks; and we capture them using a night-lighting technique. We also have an opportunity to capture adults in the spring when they are defending their territories. In that case we use a lift-net technique, where we lure the birds into a trap using a decoy and taped calls, and then capture them with a net. So this provides a couple different opportunities during the breeding season to try and recapture the birds.”
Each loon was marked with an aluminum numbered U.S. Fish and Wildlife Service band and a unique combination of colored leg-bands to aid with field identification of individuals.
Both adults of a territorial pair were fitted with an archival geolocator tag. Tags were programmed for a particular focus to document foraging patterns and dive depths while on the Great Lakes during fall migration.
The geolocator tags do not transmit any data, so loons need to be recaptured and data downloaded to a computer.
Satellite transmitters were incorporated into the study to provide detailed location data on a small set of adult common loons fitted with geolocator tags.
Transmitters were implanted in loons by a veterinarian trained in techniques developed by USGS scientists.
“The satellite transmitters provide us information on locations of the loons during migration. The information is emailed to me daily and so we get a near real-time idea of where the birds are located. This information is then presented to the public on a flash animation at our loon migration website.”
The use of this modern technology has yielded interesting insight on loon migration and wintering behavior. Scientists have developed a loon tracking web-tool available to partners and the public to follow loon movements.
Satellite telemetry has identified movements of breeding adult loons from Minnesota, Wisconsin, and Michigan.
Most of the radiomarked loons staged on the Great Lakes before moving to wintering grounds along the Gulf of Mexico and Atlantic coasts.
We have also documented the use of many lakes and reservoirs along their migration routes, and in a few cases reservoirs have served as overwintering sites.
Most of the radiomarked loons have been found to overwinter up to 80 miles off shore along the Florida coast in the Gulf of Mexico.
Males tend to leave the overwintering grounds in spring before the females, and are usually the first to arrive back on breeding lakes following ice-out.
Conclusions & Science Impact:
The use of modern satellite and geolocator technologies allow USGS researchers to identify potential sites of exposure to diseases and pollution throughout the loons annual cycle.
These critical pieces of the puzzle are necessary for state and federal resource agencies tasked with managing populations of common loons.
In the future, as private companies and collaborative partnerships continue to develop improvements to tracking technology and science, hopefully more mysteries will be unraveled for loons and other migratory species.
This podcast is a product of U.S. Geological Survey, Department of the Interior.
For more information please visit the USGS Upper Midwest Environmental Sciences Center website.
Title: Unraveling Mysteries of the Common Loon
This podcast provides insight in to the life of the common loon as captured by research scientists with USGS using modern technologies. Scientists used satellite telemetry and archival geolocator tag technologies to gain critical information on migratory movements of breeding loons in the Upper Midwest to guide conservation planning. Critical pieces of the puzzle included identifying migration staging areas and wintering areas, and also important information from dive profiles to describe foraging patterns. This information is necessary for state and federal agencies tasked with managing populations of loons in the face of stressors such as disease, pollution, and climate change.
Location: WI, Northern Wisconsin, including the Counties of Iron and Vilas,, USA
Date Taken: 1/1/2012
Video Producer: Midwest Science Podcast Team , USGS Upper Midwest Environmental Sciences Center
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