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Loon Program - Maine and New Hampshire
Loon Program - Maine and New Hampshire

Loon Research in Maine and New Hampshire

BRI biologists have been conducting loon research in Maine since 1994. Key projects include current monitoring efforts in the Rangeley Lakes area, including Lake Umbagog on the Maine-New Hampshire border, and establishing new breeding loon populations in portions of Massachusetts through the translocation of loon chicks from Maine and New York.

For more than 25 years, BRI has also conducted investigations in contaminant loads (e.g., mercury, lead, persistent organic pollutants), baseline health assessments, and other efforts to better understand Maine’s loon population. A total of 692 adult loons and 206 loon chicks have been banded in Maine and 102 (84 adult/18 chicks) have been recovered outside of their banding location (i.e., recoveries).

Lead Investigator: Alex Dalton
Contributing BRI Staff: David Evers, Bill Hanson, Jeff Fair

Rangeley Lakes

Rangeley Lakes

The Rangeley Lakes study is the longest running monitoring effort of a uniquely color-marked loon population in North America and is conducted in association with Brookfield Renewable Energy as part of their need to meet requirements of the Federal Energy Regulatory Commission (FERC). Shoreline nest placement and the loon's limited mobility on land make loon nests vulnerable to failure caused by water level fluctuations. Due to this sensitivity, the U.S. Fish and Wildlife Service, Maine Inland Fisheries and Wildlife, and other wildlife agencies identified Common Loons as a species to be evaluated in connection with the Federal Energy Regulatory Commission relicensing of reservoirs.

Overall Study Goals:

  • Maintain nearly 80 artificial nesting rafts for Common Loons on reservoirs in the Rangeley Lakes region and monitoring egg laying rates and hatching success.
  • Capture and color-band adult and juvenile loons (more than 400 loons from this area have been banded to date).
  • Monitor breeding territories on a weekly basis for overall breeding success, site fidelity, and individual performance of uniquely color-banded adult loons.
  • Determine local and long-distance movements of breeding loons.
  • Develop a long-term baseline for methylmercury availability and monitor the relationship of mercury body burdens and effects of mercury on physiology, behavior, productivity, and survival.
Lake Umbagog FERC Relicensing

Lake Umbagog FERC Relicensing

In association with Brookfield Renewable Energy and Errol Hydroelectric Company, BRI is conducting field studies to assess water level management on the reproductive success of loons and other waterfowl for the Federal Energy Regulatory Commission relicensing requirements.

Overall Study Goals:

  • Collect loon productivity, nest site measurements, and water level data on control lakes in the Upper Androscoggin watershed and from Umbagog Lake.
  • Use historic loon productivity data from Umbagog Lake and compare to reproductive parameters on local control lakes.
  • Understand reproductive success in associated waterbirds, including the Ring-necked Duck and American Black Duck.
Translocation and Restoration

Translocation and Restoration

Begining in 2015, BRI researchers developed the techniques and methodology to create a safe and replicable approach for translocation and captive rearing of loon chicks—moving them to a new lake location and confirming that they fledged from that lake. From 2015-2017, a total of 24 chicks were successfully translocated from lakes in Maine and New York to Massachusetts. 

As of spring 2020, nine adult loons returned to the lake area in Massachusetts to which they were translocated and captive-reared, and then from which they fledged. Their return marked a major milestone in the efforts to translocate Common Loons.

BRI is currently proposing to translocate up to 24 more loon chicks from Maine to Massachusetts in 2020-2021. 

Download our Loon Translocation Brochure to learn more.

Mount Desert Island

Four Common Loons were banded in Acadia National Park by BRI in 1997. Following this initial effort, the monitoring of Common Loons in Mount Desert Island began in 2002 as collaboration between BRI, Acadia National Park and the Somes-Meynell Wildlife Sanctuary. This long-term effort was initiated to provide an assessment of mercury concentrations in loons on Mount Desert Island. As part of this effort, productivity and movements of loons are annually monitored.

Overall Study Goals:

  • Capture, band and sample loon blood, feathers, and abandoned eggs to assess mercury levels in the region.
  • Color mark loons to gain specific information on territory boundaries and life history.
  • Float artificial nesting islands in loon territories where nesting success is impacted by shoreline predation or water level fluctuations.


Peer-reviewed Publications

  • Mitro, M. G., D. C. Evers, M. W. Meyer, and W. H. Piper. 2010. Common Loon survival rates and mercury in New England and Wisconsin. Journal of Wildlife Management 72:665-673.
  • Evers, D.C., L. Savoy, C.R. DeSorbo, D. Yates, W. Hanson, K.M. Taylor, L. Siegel, J.H. Cooley, M. Bank, A. Major, K. Munney, H.S. Vogel, N. Schoch, M. Pokras, W. Goodale, and J. Fair. 2008. Adverse effects from environmental mercury loads on breeding common loons. Ecotoxicology 17:69-81.
  • DeSorbo, C.R., K.M. Taylor, D.E. Kramar, J. Fair, J.H. Cooley, Jr., D.C. Evers, W. Hanson, H.S. Vogel, and J.L. Atwood. 2007. Reproductive advantages for Common Loons using rafts. Journal of Wildlife Management 71 (4):1206-1213.
  • Evers, D.C., Y.J. Han, C.T. Driscoll, N.C. Kamman, M.W. Goodale, K.F. Lambert, T.M. Holsen, C.Y. Chen, T.A. Clair, and T. Butler. 2007. Identification and Evaluation of Biological Hotspots of Mercury in the Northeastern U.S. and Eastern Canada. BioScience 57:29-43.
  • Evers, D. C., N. M. Burgess, L. Champoux, B. Hoskins, A. Major, W. M. Goodale, R. J. Taylor, R. Poppenga, and T. Daigle. 2005. Patterns and interpretation of mercury exposure in freshwater avian communities in northeastern North America. Ecotoxicology 14:193-221.
  • Evers, D.C. and T.A. Clair. 2005. Mercury in Northeastern North America: a synthesis of existing databases. Ecotoxicology 14:7-14.
  • Haefele, H. J., I. Sidor, D. C. Evers, D. E. Hoyt, and M. A. Pokras. 2005. Hematologic and physiologic reference ranges for free-ranging adult and young Common Loon (Gavia immer). Journal of Zoo and Wildlife Medicine 36:385–390.
  • Evers, D.C., K. M. Taylor, A. Major, R. J. Taylor, R. H. Poppenga, and A. M. Scheuhammer. 2003. Common Loon eggs as indicators of methylmercury availability in North America. Ecotoxicology 11:6981.
  • Evers, D.C., J.D. Kaplan, M.W. Meyer, P.S. Reaman, W.E. Braselton, A. Major, N. Burgess, and A.M. Scheuhammer. 1998. Geographic trend in mercury measured in Common Loon feathers and blood. Environmental Toxicology and Chemistry 17:173-183.

Visit our Multimedia Library for details on these and other BRI peer-reviewed publications.

Photo Credits: Header photo © BRI-Jonathan Fiely; Rangeley Lake © BRI-Deborah McKew; Loon nesting on shore © BRI-Jonathan Fiely; Loon on Raft © BRI-Jonathan Fiely; Infographic © BRI-Adelaide Tyrol/RavenMark
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