mt.gov
Montana Fish, Wildlife & Parks
 

Animal Field Guide

in Partnership with
Montana Natural Heritage Program.
Search Field Guide

Additional Media
(click on image to view)
Common Loon Distribution Map - Bird Distribution generated from Montana Bird Distribution Database Common Loon Nest - Eggs of Gavia Immer Common Loon Call - Copyright by Borror Laboratory of Bioacoustics, Department of Evolution, Ecology, and Organismal Biology, Ohio State University, Columbus, OH, all rights reserved. Common Loon, Distinct Black & White Markings - Gavia immer Common Loon, In Shadow - Gavia immer
Related Information

Please visit the following pages for more infomation from Fish, Wildlife & Parks related to the Animal Field Guide.

About this Guide

The Montana Animal Field Guide is the product of a partnership between Montana Fish, Wildlife & Parks and the Natural Heritage Program. The Natural Heritage Program was established by the Montana State Legislature in 1983, the program is located in the Montana State Library, where it is part of the Natural Resource Information System.


Gavia immer
Common Loon, Closeup of Head
Common Loon

Gavia immer
(Gaviidae)

Montana Species of Concern
Global Rank: G5
State Rank: S2B

Agency Status
USFWS:
USFS: SENSITIVE
BLM: SENSITIVE
 

General Description
The Common Loon is a large and mainly aquatic bird. Males are generally larger than females. Adult body length ranges from 71 to 92 cm (28 to 36 inches) with wingspans to 147 cm (58 inches). Weight varies ranging from 1.6 to 8 kg (3.5 to 17.6 lb.) with an average of about 3 to 4 kg (6.6 to 8.8 lb.) (McIntyre 1988, McIntyre and Barr 1997). The feet are located far back on the body and are large, webbed, and sweep to the side rather than forward under the belly. This trait makes it difficult for loons to walk on land but allows more efficient swimming underwater.

Sexes are indistinguishable based on plumage. The head and neck of breeding adults are black with a green gloss. The back, wings and sides are also black. Scapulars and wing-coverts have large white markings, which is a distinctive field mark. The eye is red. Common Loons have a broad patch of vertical white stripes on the side of the neck and a smaller patch on the upper foreneck. The breast and belly are white and the bill is straight, heavy and black (McIntyre and Barr 1997). In the non-breeding plumage, the head, neck and upper parts are dark gray to dark brown. The cheeks, throat, and underparts are white. The bill is brownish-gray to pale bluish-gray or horn colored. The iris is brown. The tail is dark brown, tipped with white (Bent 1919, Johnsgard 1987, McIntyre 1986, 1988). Juvenile plumage is similar to the adult non-breeding plumage, although the upperparts have paler and more conspicuous feather margins than those of adults, and the throat and sides of the neck are more finely streaked with brown. This plumage is worn until the following summer when the birds molt into more adult-like basic plumage (Palmer 1962, McIntyre 1988).

Common Loons are known for their distinctive calls, three of which are heard on summer breeding lakes. The wail, a long almost mournful cry, the tremolo, a high pitched, rapid, five-beat call, and probably the best known is the yodel which is given only by males during territorial confrontations. Common Loons generally lay 2 subelliptical to ovoid shaped eggs which vary from deep olive to light brown in color, with irregular dark brown or black spots.

Diagnostic Characteristics
The Common Loon is a large loon with a heavy, black bill and an easily recognizable breeding plumage. The large size of the Common Loon distinguishes it from the Pacific Loon (G. pacifica) and the Red-throated Loon (G. stellata), as well as the Arctic Loon (G. arctica), which has never occurred in Montana. Only the Yellow-billed Loon is comparable in size. It, however, has a distinctive yellow bill as well as subtle differences in plumage (McIntyre and Barr 1997).

Migration
In Montana, spring migration begins in early to mid-March. Fall migration starts in late August and may continue through October in Montana. Transient sightings occur throughout the state during spring migration, especially between April and June, and fall migration, between September and November (Montana Bird Distribution 2002). The species is not known to remain on breeding lakes throughout the year, although there are observations of Common Loons remaining in Montana throughout the winter.

Habitat
In Montana, Common Loons will not generally nest on lakes less than about 13 acres in size or over 5000 feet in elevation (Skaar 1990). Successful nesting requires both nesting sites and nursery areas. Small islands are preferred for nesting, but herbaceous shoreline areas, especially promontories, are also selected. Nursery areas are very often sheltered, shallow coves with abundant small fish and insects (Skaar 1990). Most Montana lakes inhabited by Common Loons are relatively oligotrophic and have not experienced significant siltation or other hydrological changes.

The quantity and quality of nesting habitat limits the loon population of northwest Montana. Skaar (1990) estimated the state's "carrying capacity" at 185 potential nesting territories, based on the size and number of lakes within the species' breeding distribution. He assumed 100 ha of surface area per pair. Kelly (1992) documented a density of 72.2 surface ha of water per adult loon for the Tobacco, Stillwater, Clearwater, and Swan River drainages.

Food Habits
No food habit data is available for Montana. Generally, Common Loons dive from the surface and feed mainly on fishes but are opportunistic and will eat any suitable prey they can readily see and capture (McIntyre 1988) including amphibians and various invertebrates (Terres 1980). Their primary food on breeding lakes is yellow perch (Perca flavescens), followed by other shallow, warmwater fish and minnows (Cyprinidae) (Olson and Marshall 1952, Palmer 1962, Barr 1973, McIntyre 1986). Salmonids are taken on lakes that have low populations of other fish species (McIntyre 1988). On the Great Lakes, alewives (Alosa pseudoharengus) appear to be the most common prey item (McIntyre 1988). Crustaceans, especially crayfish (Decapoda), are commonly taken, and plant material is occasionally eaten (Palmer 1962, McIntyre 1988). On lakes without fish, loons have been reported feeding on molluscs, insects, amphipods and amphibians (Munro 1945, Parker 1985). Young birds have a diversified diet consisting primarily of small fish and minnows, aquatic insects and crayfish (McIntyre 1988).

Winter foods are reported to include flounder (Pleuronectoidei), rock cod (Gadus morhua), herring (Clupea spp.), menhaden (Brevoortia patronus), sea trout (Salmo spp.), sculpin (Leptocottus armatus), and crabs (Palmer 1962, McIntyre 1988). A detailed study of winter-feeding patterns and preferences has not been conducted.

If nesting on a small lake, they may use an adjacent lake for supplementary foraging (Johnsgard 1987). In Ontario, loons attempting to raise a chick on a fishless, acidic lake fed the chick benthic algae and possibly benthic invertebrates, but flew to other lakes to feed themselves (Alvo et al. 1988). They feed usually in waters less than 5 m deep.

Ecology
In 1985, Montana's population was estimated at at least 105 birds (Skaar 1986). No other information is available for the state. Other ecological data, from different areas in the species' range, indicate lakes smaller than 80 ha generally support only one breeding pair. Typically, territory size is larger on large lakes than on small lakes. Wintering birds may defend feeding territories during the day, and gather into rafts at night. The ecology of wintering loons is not well studied. McIntyre (1978) found that loons off the Virginia coast maintained individual feeding territories of four to eight ha during the day and rafted together at night. Activity patterns were significantly correlated with tidal changes. Maintenance behavior was greatest during the mid-period of tidal rise. Feeding activities peaked late in the flood tide and during the first half of the ebb tide.

In Rhode Island, no winter-feeding territories, feeding assemblages, or tide-correlated activity patterns were noted by Daub (1989).

Reproductive Characteristics
Up to 86 lakes in Montana have had at least one pair of Common Loons present during the breeding season and up to 33 lakes have had Common Loon chicks present. On an annual basis, about 160-180 Common Loons can be found on Montana lakes. Between 1999-2001, 60%-80% of these adults formed territorial pairs, but less than half produced chicks (Bissell 2002). Chick production in Montana has ranged between 33-51 chicks, with an average of 39.5 chicks produced per year. Average clutch size is 1.87 and the average chicks per successful nest (1982-1985) was 1.39 (Skaar 1969).

Most other reproductive data collected on Common Loons comes from studies in other areas of the species' range. These studies indicate the timing of spring arrival is correlated with latitude and dictated primarily by ice-out phenology (McIntyre 1988). Males typically return first, especially in southern breeding areas (McIntyre 1975, 1988; Sutcliffe 1980). However, pairs often arrive together at northern lakes (McIntyre 1988). Territories are established immediately after arrival and may change in size as the breeding season progresses, expanding after the chicks hatch and shrinking for failed pairs (McIntyre 1988).

Courtship begins shortly after territory reoccupation and involves quiet, shared displays including simultaneous swimming, head posturing, and short dives. Vocalizations are not extensive. Copulation sequences are stereotyped, typically last from three to ten minutes, and take place on land (McIntyre 1988). Some copulation sites become nest sites (McIntyre 1975). It is believed that pairs re-mate each spring and that courtship serves primarily to renew the pair bond (McIntyre 1988). Nest-building is conducted by both members of the pair and may immediately follow copulation, sometimes lasting over four days (McIntyre 1975, 1988). Egg laying begins one to 4.5 weeks after spring arrival and eggs are typically laid at two-day intervals (McIntyre 1975). Most clutches contain two eggs, and most one-egg clutches result from loss of the first egg (McIntyre 1975, Titus and VanDruff 1981). ). Both pair members incubate, beginning with the laying of the first egg, for an average period of 28-29 days, ranging from 26-31 days (Bent 1919, Olson and Marshall 1952, Palmer 1962, McIntyre 1975). An adult is present at the nest 99 percent of the time, and the eggs hatch within a day of one another (McIntyre 1975).

Chicks leave the nest within 24 hours of hatching and are soon moved to nursery areas (McIntyre 1988). Chicks are fed largely by their parents until eight weeks of age (McIntyre 1988) even though chicks are capable of short dives at the time of nest departure and may capture some fish by the second or third week (McIntyre 1975). Adults aggressively defend chicks underwater and on the surface (McIntyre 1988). Most juveniles are capable of flight at 11-12 weeks (Barr 1973, McIntyre 1975), and some leave their small, natal lakes or parental territories shortly afterwards (McIntyre 1975).

Common Loons appear to be faithful to breeding territories. Banded adults have been recaptured on the same breeding territory in subsequent years (McIntyre 1974, Yonge 1981). Yearly reuse of nest sites and nursery areas has been documented (Strong et al. 1987, Jung 1991), but it is not known whether the same individuals were involved. Sonograms of yodel calls suggest that individual males return to the same territory each year (McIntyre 1988, Miller 1989). Little is known about mate fidelity of breeding pairs.

Management
Management of Common Loons and their habitat in Montana should include multiple methods and techniques based on the management intensity level necessary on a particular lake or area. These techniques include, but are not limited to, monitoring, protection from disturbance by people, and protection of nesting and nursery habitat. The Montana Loon Society monitors Common Loon reproduction each year in Montana. Potential breeding lakes are visited throughout the state and observations are made of adults and chicks. Observing Common Loons on lakes throughout Montana is a productive and valuable method of monitoring, but only reveals limited information; loons use of the lake and the production of chicks. More intensive monitoring should be implemented in areas where loons are known to occur but have low nest success. This increased monitoring activity would reveal valuable information regarding nesting attempts and the timing and causes of nest failure or chick loss (Dolan 1994). Lakes where no evidence of breeding exists, but Common Loons are present, should be monitored in the spring for any sign of nesting. This added measure would assist in determining the cause of failure at these locations and would also provide a better estimate of total breeding pairs in Montana and rates of success in the population (Dolan 1994). Additional monitoring efforts should be focused on effectiveness of signs in nesting areas and nurseries. Posting floating signs is an effective management method to protect Common Loon nesting sites and nursery areas from disturbance by people. Placing informative signs in key public areas, such as boat ramps, detailing the function and reason for floating signs, and issuing press releases about loons and chick sensitivity during the breeding season, are both important aspects of floating sign success or failure (Dolan 1994). Another management option to protect Common Loons from human disturbance is control of new access to lakes. Methods of controlling access to lakes include preventing new access to remote lakes that have little or no access currently, moving existing access sites away from nesting and nursery areas, avoiding removal of cover between a road/trail and a lake, and closing or rerouting trails that are in close proximity to nesting areas (Dolan 1994). Management methods that would protect nesting and nursery habitat are varied in scope depending on the location within the state and the particular situation. Primary to the continued use of Montana lakes by Common Loons is the protection of nesting and nursery habitat from destruction resulting from construction, dredging, or filling. Avoiding artificial water level fluctuations is another technique in protecting nest site habitat. Keep water levels consistent and only allow flooding or drawdown practices to occur after the breeding cycle has been completed. Other ways of protecting loon habitat includes implementing no-wake zones to prevent erosion of nesting habitat and working with homeowner associations and other owners, thereby allowing the public to become active in the protection of Common Loons and loon habitat on their lake (Dolan 1994). Common Loons are listed as a sensitive species by the USFS, Region 1 and they are a Species of Management Concern in Region 6 (U.S. Fish and Wildlife Service 1995).

Citations & Sources
  • Alexander, L. L. 1985. Trouble with loons. Living Bird Quarterly. 4:10-13.
  • Alvo, R. 1981. Marsh nesting of common loons (GAVIA IMMER). Can. Field Nat. 95:357.
  • Alvo, R., D. J. T. Hussell, and M. Berril. 1988. The breeding success of common loons (GAVIA IMMER) in relation to alkalinity and other lake characteristics in Ontario. Can. J. Zool. 66:746-752.
  • American Ornithologists` Union. 1983. Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 p.
  • Barklow, W. E., and J. A. Chamberlain. 1984. The use of the tremolo call during mobbing by the common loon. Journal of Field Ornithology 55:258-9.
  • Barr, J. F. 1973. Feeding biology of the common loon (GAVIA IMMER) in oligotrophic lakes of the Canadian shield. University of Guelph, Guelph, Ontario, Canada. Ph.D. dissertation.
  • Barr, J. F. 1986. Population dynamics of the common loon (GAVIA IMMER) associated with mercury-contaminated waters in northwestern Ontario. Occas. Paper No. 56, Canadian Wildlife Service, Ottawa, Ontario, Canada.
  • Bent, A.C. 1919. Life histories of North American diving birds. U.S. Natl. Mus. Bull. 107. Washington, D.C.
  • Bissell, G. 2002. Second annual common loon report. Montana Fish, Wildlife and Parks. 9 pp. plus appendices.
  • Bull, J. 1974. Birds of New York state. Doubleday/Natural History Press, Garden City, New York. Reprint, 1985 (with Supplement, Federation of New York Bird Clubs, 1976), Cornell Univ. Press, Ithaca, New York.
  • Daub, B.C. 1989. Behavior of Common Loons in winter. Journal of Field Ornithology 60:305-311.
  • Dolan, P. M. 1994. The Common loon (GAVIA IMMER) in the northern region: biology and management recommendations. Unpublished report. U.S.D.A. Forest Service Region 1. 76 pp.
  • Dulin, G. S. 1987. Pre-fledging feeding behavior and sibling rivalry in common loons. Central Michigan University, Mt. Pleasant, Michigan. M.S. thesis.
  • Fair, J. S. 1979. Water level fluctuations and common loon nest failure. Pages 57-63 in S. Sutcliffe (editor). Proceedings of the second North American conference on common loon research and management. National Audubon Society, New York, New York. 162 pp
  • Fay, L. D. 1966. Type E botulism in Great Lakes water birds. Pages 139-149 in Trans. Thiry-first N. Amer. Wild. and Nat. Res. Conf.
  • Fox, G. A., K. S. Yonge, and S. G. Sealy. 1980. Breeding performance, pollutant burden and eggshell thinning in common loons GAVIA IMMER nesting on a boreal forest lake. Ornis Scand. 11:243-8.
  • Frank, R., H. Lumsden, J.F. Barr, and H.E. Braun. 1983. Residues of organochlorine insecticides, industrial chemicals, and mercury in eggs and tissues taken from healthy and emaciated common loons, Ontario, Canada, 1968-1980. Archives of Environmental Con
  • Haney, J. C. 1990. Winter habitat of common loons on the continental shelf of the southeastern United States. Wilson Bull. 102:253-263.
  • Heimburger, M.D., D. Euler, and J. Barr. 1983. The impact of cottage development on common loon reproductive success in central Ontario. Wilson Bulletin 95:431-439.
  • Johnsgard, P. A. 1987. Diving birds of North America. Univ. Nebraska Press, Lincoln. xii + 292 pp.
  • Jung, R. E. 1991. Effects of human activities and lake characteristics on the behavior and breeding success of common loons. The Passenger Pigeon 53:207-218.
  • Kaveney, D. E., and C. C. Rimmer. 1989. The breeding status of common loons in Vermont--1989. Vermont Inst. Nat. Sci., Woodstock, Vermont. Unpublished report.
  • Kerlinger, P. 1982. The migration of common loons through eastern New York. Condor 84:97-100.
  • Lenard, S., J. Carlson, J. Ellis, C. Jones, and C. Tilly. 2003. P. D. Skaar's Montana Bird Distribution, 6th Edition. Montana Audubon, Helena, Montana. vi + 144 pp.
  • Locke, L. M., S. M. Kerr, and D. Zoromski. 1982. Lead poisoning in common loons (GAVIA IMMER). Avian Diseases 26:392-6.
  • McIntyre, J. W. 1974. Territorial affinity of a common loon. Bird-Banding 45:178.
  • McIntyre, J. W. 1975. Biology and behavior of the common loon (GAVIA IMMER) with reference to its adaptability in a man-altered environment. University of Minnestoa, Minneapolis, Minnesota. Ph.D. dissertation.
  • McIntyre, J. W. 1978. Wintering behavior of common loons. Auk 95:396-403.
  • McIntyre, J. W. 1983. Nurseries: a consideration of habitat requirement during the early chick-rearing period in common loons. Journal of Field Ornithology 54:247-53.
  • McIntyre, J. W. 1986. Common loon. Pages 679-95 in R. L. Di Silvestro (editor). Audubon Wildlife Report 1986. National Audubon Society, New York, New York.
  • McIntyre, J. W. 1988. The common loon: spirit of northern lakes. Univ. Minnesota Press, Minneapolis. x + 200 pp.
  • McIntyre, J. W., and J. F. Barr. 1983. Pre-migratory behavior of common loons on the autumn staging grounds. Wilson Bulletin 95:121-5.
  • McPeek, G. A., and D. C. Evers. 1989. Guidelines for the protection and management of the common loon in southwest Michigan: a recovery plan. Kalamazoo Nature Center, Kalamazoo, Michigan. Unpublished report.
  • Miller, E. 1989. Population turnover rate and early-season usage of multi-lake territories by common loons in upper Michigan/Wisconsin. North American Loon Fund, Meredith, New Hampshire. Unpublished report.
  • Miller, E., and T. Dring. 1988. Territorial defense of multiple lakes by common loons: a preliminary report. Pages 1-14 in P. I. V. Strong (editor). Conf. on Common Loon Res. and Manage., North American Loon Fund, Meredith, New Hampshire.
  • Montana Bird Distribution Committee. 1996. P.D. Skaar's Montana Bird Distribution, fifth edition. Montana Natural Heritage Program Special Publication No. 3.
  • Munro, J. A. 1945. Observations of the loon in the Cariboo Parklands, British Columbia. Auk 62:38-49.
  • NatureServe Explorer: An online encyclopedia of life [web application]. 2002. Version 1.6 . Arlington, Virginia, USA: NatureServe. Available: http://www.natureserve.org/explorer. (Accessed: March 20, 2003 ).
  • Okoniewski, J. C., and W. B. Stone. 1987. Some observations on the morbidity and mortality of, and environmental contaminants in, common loons (GAVIA IMMER) in New York, 1972-1986. New York State Department Environmental Conservation, Delmar, New York. Un
  • Olson, S. T., and W. H. Marshall. 1952. The common loon in Minnesota. Minnesota Mus. Nat. Hist., Occas. Paper No. 5, University of Minnesota Press, Minneapolis, Minnesota.
  • Palmer, R. S. 1962. Handbook of North American birds. Vol. 1. Loons through flamingos. Yale University Press, New Haven. 567 pp.
  • Parker, K. E. 1985. Foraging and reproduction of the common loon (GAVIA IMMER) on acidified lakes in the Adirondack Park, New York. College of Environmental Science and Forestry, State University of New York, Syracuse, New York. M.S. thesis.
  • Parker, K. E. 1988. Common loon reproduction and chick feeding on acidified lakes in the Adirondack Park, New York, New York. Canadian Journal of Zoology 66:804-10.
  • Parker, K. E., and R. L. Miller. 1988. Status of New York's common loon population--comparison of two intensive surveys. Pages 145-56 in P. I. V. Strong (editor). 1987 Conference on Common Loon Research and Management. North American Loon Fund, Meredith,
  • Pokras, M. A. In press. Lead toxicosis from ingested fishing sinkers in adult common loons (GAVIA IMMER) in New England. J. of Zoo. and Wildl. Medicine.
  • Powers, K. D., and J. Cherry. 1983. Loon migrations off the northeastern United States. Wilson Bulletin 95:125-32.
  • Ream, C.H. 1976. Loon productivity, human disturbance and pesticide residues in northern Minnesota. Wilson Bulletin 88:427-432.
  • Rimmer, C. C. 1992. Common loon, GAVIA IMMER. Pp. 3-30 in K. J. Schneider and D. M. Pence, (eds.), Migratory nongame birds of management concern in the Northeast. U.S. Fish and Wildlife Service, Newton Corner, Massachusetts. 400 pp.
  • Rimmer, C. C., and D. E. Kaveney. 1988. The breeding status of common loons in Vermont--1988. Vermont Inst. Nat. Sci., Woodstock, Vermont. Unpublished report.
  • Root, T. 1988. Atlas of wintering North American birds. An analysis of Christmas bird count data. Univ. Chicago Press. 336 pp.
  • Skaar, D. 1990. Montana common loon management plan. Unpublished report prepared for U.S. Forest Service, Region 1. 61 pp.
  • Strong, P. I. V. 1985. Habitat selection by common loons. University of Maine, Orono, Maine. Ph.D. dissertation.
  • Strong, P. I. V. and J. A. Bissonette. 1989. Feeding and chick-rearing areas of common loons. J. Wildl. Manage. 53:72-76.
  • Strong, P. I. V., Bissonette, J. A. and J. S. Fair. 1987. Reuse of nesting and nursery areas by common loons. Journal of Wildlife Management 51(1):123-127.
  • Stroud, R. K., and R. E. Lange. 1983. Information summary: Common loon die-off winter and spring of 1983. Natl. Wildl. Health Lab., U.S. Fish and Wildlife Service, Madison, Wisconsin.
  • Sutcliffe, S. A. 1978. Pesticide levels and shell thickness of common loon eggs in New Hampshire. Wilson Bulletin 90:637-40.
  • Sutcliffe, S. A. 1980. Aspects of the nesting ecology of common loons in New Hampshire. University of New Hampshire, Durham, New Hampshire. M.S. thesis.
  • Terres, J. K. 1980. The Audubon Society encyclopedia of North American birds. Alfred A. Knopf, New York.
  • Titus, J. R. and L. W. Van Druff. 1981. Response of the common loon to recreational pressure in the Boundary Waters Canoe Area, northeastern Minnesota. Wild. Monog. No. 79.
  • Vermeer, K. 1973. Some aspects of the breeding and mortality of common loons in east-central Alberta. Canadian Field-Naturalist 87:403-8.
  • Williams, L. E. 1973. Spring migration of common loons from the Gulf of Mexico. Wilson Bulletin 85:238.
  • Wood, R. L. 1979. Management of breeding loon populations in New Hampshire. Pages 141-6 in S. Sutcliffe (editor). Proceedings of the Second North American Conference on Common Loon Research and Management. National Audubon Society, New York, New York.
  • Yonge, K. S. 1981. The breeding cycle and annual production of the common loon (GAVIA IMMER) in the boreal forest region. University of Manitoba, Winnipeg, Manitoba. M.S. thesis.
  • Zicus, M. C., R. H. Hier, and S. J. Maxson. 1983. A common loon nest from Minnesota containing four eggs. Wilson Bulletin 95:672-3.
  • Zimmer, G. E. 1979. The status and distribution of the common loon in Wisconsin. University of Wisconsin, Stevens Point, Wisconsin. M.S. thesis.
 

Website Navigation
 
State of Montana
Privacy & Security PolicyAccessibilityContact Us
This page is from the Montana Animal Field Guide. [http://fwp.mt.gov/fieldguide/speciesDetail.aspx?elcode=ABNBA01030]
Friday, February 06, 2009 - 6:40:20 AM