Gavia immer

A large (28-36 inches) loon, the Common Loon in summer is most easily identified by its black head and bill, black-and-white “crosshatched” back, and conspicuous white breast patch visible immediately above the waterline. Winter Common Loons are dark above and pale on the breast, throat, and head, appearing slightly darker than the related Red-throated Loon (Gavia stellata). Male and female Common Loons are similar to one another in all seasons. The Common Loon inhabits parts of Eurasia (where it is known as the Great Northern Diver) and North America. In the New World, this species breeds across Alaska, Canada, Greenland, and the northern tier of the United States. Red-throated Loons breeding in North America spend the winter along the Pacific coast from southern Alaska south to central Mexico, along the Atlantic Coast from Nova Scotia to Florida, along the Gulf coast from Florida to eastern Mexico, and at a few locations in the interior southeast. In the Old World, this species breeds in Iceland, wintering along the coasts of Northern Europe. In summer, Common Loons breed in large lakes either on the tundra or in evergreen forests. During the winter, Common Loons are found along the coast in near-shore waters and on large bays and reservoirs. On migration, this species may be found on large bodies of freshwater in the interior. Common Loons primarily eat small fish, which they catch by diving. In appropriate habitats in summer, Common Loons may be seen nesting on small islands in lakes or directly on the lake shore. At this time of the year, birdwatchers may hear this species’ haunting “yodeling” calls on calm nights. During the winter, Common Loons are most easily observed out at sea through binoculars or spotting scopes, and may be seen floating low in the water, diving below the surface in pursuit of prey, or flying awkwardly close to the tops of the waves. This species is primarily active during the day, but calls at night during the breeding season.

Threat Status: Least concern

The Common Loon or Great Northern Diver (Gavia immer), with its eerie yodeling and moaning calls, is often viewed as a symbol of the wilderness of the northern portions of North America and Europe, where it breeds (its calls are so evocative that filmakers often use them even in quite unrealistic geographic contexts to achieve a desired atmosphere). The breeding habitat of G. immer is mainly on lakes in the coniferous forest zone, as well as beyond the treeline into open tundra. The North American winter range includes the Pacific coast of North America from the Aleutian Islands south to Baja California and Colima, the Atlantic coast from Newfoundland south to southern Florida and west to Tamaulipas, and, less frequently (especially in the north) around inland waters throughout most of the continental United States. In the western Palearctic, G. immer winters along the Atlantic coast south to northwestern Africa, casually to the eastern Atlantic islands and through Europe to the Mediterranean and Black Seas. In the winter, they are found mainly on the ocean close to shore and on bays and inlets, as well as on large ice-free lakes and reservoirs. They feed mainly (although not exclusively) on small fish (up to around 25 cm), foraging by diving and swimming underwater. (Kaufman 1996; AOU 1998)

This species is most abundant in Canada and the Northern United States. Common loons breed on lakes and other waterways from western Greenland west across Canada and the northernmost United State, including Alaska. They winter along both coasts of North America as far south as Baja California and Texas. There is a breeding population on Iceland, and the species is a frequent winter visitor to the western coasts of Europe.

Biogeographic Regions: nearctic (Native ); palearctic (Native )

W Palearctic and N America; winters to s US and s Palearctic.

Arctic Ocean, Belgian Exclusive Economic Zone, European waters (ERMS scope), Gulf of Maine, Gulf of Mexico, Mediterranean Sea, North West Atlantic, Polish Exclusive Economic Zone, Portuguese Exclusive Economic Zone, Spanish Exclusive Economic Zone, Swedish Exclusive Economic Zone, United Kingdom Exclusive Economic Zone, Wimereux

Newfoundland to the Gulf of Mexico

The Common Loon breeds in much of Canada and Alaska, parts of northern United States, southern parts of Greenland (to Denmark) and in Iceland. It winters on sea coasts or on larger lakes over a much wider area including the Antlantic coast of Europe from Finland to Portugal and the western Mediterranean, the Atlantic coast of North America down to northern Mexico, and the Pacific coast of North America from northern Mexico to the tip of Alaska (USA)¹.

This species is most abundant in Canada and the Northern United States. Common loons breed on lakes and other waterways from western Greenland west across Canada and the northernmost United State, including Alaska. They winter along both coasts of North America as far south as Baja California and Texas. There is a breeding population on Iceland, and the species is a frequent winter visitor to the western coasts of Europe.

Biogeographic Regions: nearctic (Native ); palearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Nesting occurs in Iceland, Greenland, and across Canada and the northern United States to Alaska, and south to California, Montana, the Great Lakes region, New York, New England, and Nova Scotia (AOU 1998). In winter, this loon occurs mainly along the Pacific coast from Aleutians to Baja California and Sonora, along the Atlantic and Gulf coasts from Newfoundland to Florida and west to Texas, and in the western Palearctic along the Atlantic coast to northwestern Africa (AOU 1998). In North America, this species is most concentrated in winter along the South Carolina coast, around Vancouver Island, in northern California, along the Gulf Coast adjacent to the Florida panhandle, and along the Atlantic seaboard from Massachusetts to Maine (Root 1988).

Aleutian Islands east to Iceland and Greenland Spreads south past 30° N in the winter.

Common loons are large swimming birds with long bodies (70 to 90 cm long, 1.6 to 8.0 kg) that sit low in the water. They have straight, thick, "daggerlike" bills that are black in the breeding season and gray during the rest of the year. The plumage of loons is black, white and gray. During the breeding season, common loons have a black head with a white and black striped necklace, and a checkered pattern on their back. During the winter, they are evenly gray on the head and back, with a white neck and underside. The common loon can be distinguished from other loons by its unique plumage patterns during the breeding season and black bill. During the winter, common loons can be distinguished by the indentation of the white neck color at mid-neck. Common loons are also larger than most loon species, except Gavia adamsii.

Male and female common loons look alike, though the males are usually larger than the females. Young common loons look similar to winter adults, but have more white on their head and back. They keep this juvenile plumage through their first summer.

Range mass: 1600 to 8000 g.

Range length: 70 to 90 cm.

Average wingspan: 152 cm.

Sexual Dimorphism: sexes alike; male larger

Common loons are large swimming birds with long bodies (70 to 90 cm long, 1.6 to 8.0 kg) that sit low in the water. They have straight, thick, "daggerlike" bills that are black in the breeding season and gray during the rest of the year. The plumage of loons is black, white and gray. During the breeding season, common loons have a black head with a white and black barred necklace, and a checkered pattern on their back. During the winter, they are evenly gray on the head and back, with a white neck and underside. The common loon can be distinguished from other loons by its unique plumage patterns during the breeding season and black bill. During the winter, common loons can be distinguished by the indentation of the white neck color at mid-neck. Common loons are also larger than most loon species, excluding yellow-billed loons.

Male and female common loons look alike, though males are usually larger than the females. Young common loons look similar to winter adults, but have more white on their head and back. This juvenile plumage is maintained through their first summer.

Range mass: 1600 to 8000 g.

Range length: 70 to 90 cm.

Average wingspan: 152 cm.

Sexual Dimorphism: sexes alike; male larger

Length: 81 cm

Weight: 4134 grams

Length: 76 cm, Wingspan: 137 cm

See Stallcup (1994) for information on identification of North American loons.

Loons nest on lakes and large ponds. Weather restricts habitat selection, because loons cannot nest on frozen water. They prefer to nest offshore, on islands, islets, or floating mounds of vegetation in shallow water. In winter, loons migrate to shallow coastal marine habitat.

Range depth: 0 to 80 m.

Habitat Regions: temperate ; saltwater or marine ; freshwater

Aquatic Biomes: lakes and ponds; rivers and streams; coastal ; brackish water

Wetlands: marsh

Habitat and Ecology

Systems

• Terrestrial
• Freshwater
• Marine

Loons nest on lakes and large ponds. Weather restricts habitat selection, because loons cannot nest on frozen water. They prefer to nest offshore, on islands, islets, or floating mounds of vegetation in shallow water. In winter, loons migrate to shallow coastal marine habitat.

Range depth: 0 to 80 m.

Habitat Regions: temperate ; saltwater or marine ; freshwater

Aquatic Biomes: lakes and ponds; rivers and streams; coastal ; brackish water

Wetlands: marsh

Depth range based on 5626 specimens in 1 taxon.
Water temperature and chemistry ranges based on 519 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 0.867 - 24.836
  Nitrate (umol/L): 0.240 - 9.166
  Salinity (PPS): 6.428 - 36.148
  Oxygen (ml/l): 4.687 - 8.067
  Phosphate (umol/l): 0.088 - 0.800
  Silicate (umol/l): 0.868 - 16.169

Graphical representation

Temperature range (°C): 0.867 - 24.836

Nitrate (umol/L): 0.240 - 9.166

Salinity (PPS): 6.428 - 36.148

Oxygen (ml/l): 4.687 - 8.067

Phosphate (umol/l): 0.088 - 0.800

Silicate (umol/l): 0.868 - 16.169
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Comments: Breeding habitat includes usually clear lakes (McIntyre 1988) containing both shallow and deep water areas(McIntyre 1975, 1988; Strong 1985). In studies comparing lakes with and without loons, higher turbidity was suggested as a factor influencing lack of occupancy (Barr 1973, McIntyre 1988). Nest sites are on small islands(Olson and Marshall 1952, Vermeer 1973, McIntyre 1975, Titus and VanDruff 1981, Strong 1985), quiet backwaters (Strong 1985), or mainland shores. Loons have been found nesting in marshy portions of lakes in water depths no greater than 0.5 m (Alvo 1981). Optimal nest sites, as measured by degree of success, include overhead cover to conceal eggs from predators, protection from wind and waves, good visibility by incubating adults, and a steep slope adjacent to the nest for adequate underwater approaches and exits (McIntyre 1975, 1983, 1988). Brood-rearing areas are typically located in shallow coves of fairly uniform depth, sheltered from prevailing winds and wave action, and are independent of nest site location (McIntyre 1983, Strong 1985). Adults tending chicks prefer shallow water areas (< 2 m) close to land (< 150 m) (Strong 1985, Strong and Bissonette 1989). Deepwater areas (> 4 m) distant from land (> 250 m) are avoided by feeding adults and adults tending chicks, but are often used for social interactions (Strong 1985). Breeding adults usually feed outside of nursery areas (Strong 1985), occasionally outside of their territories (McIntyre 1983), and may visit nearby lakes for feeding (Miller and Dring 1988).

In winter and during migration, common loons use inland lakes and rivers and marine and estuarine coastal waters. Most nonbreeding subadults apparently remain in coastal areas during breeding season. Winter primarily in coastal marine habitats, including bays, coves, channels, inlets and other shallow areas (Bent 1919, McIntyre 1988, Palmer 1962). Some individuals overwinter on inland lakes and rivers, although this appears to be largely weather influenced (McIntyre 1988). While shallow, inshore waters appear to be utilized more frequently than deeper, offshore waters (McIntyre 1978, Daub 1989), some use continental shelf waters up to 100 m in depth and 100 km from land (Haney 1990). In the southeastern U.S. (between 29 degrees and 35 degrees North latitude), wintering loons were most common in waters up to 19 m deep but were rare or absent in highly turbid waters five to 15 km from shore. Loon distribution shifted farther offshore during midwinter to avoid increases in these turbid water areas (Haney 1990). Feeding typically occurs in water depths less than five meters, while maintenance activities (e.g., preening and drifting) take place in deeper water (McIntyre 1978, Daub 1989).

Winter: Coastal waters Summer: Large wooded lakes, tundra pools

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Northward migration occurs mainly in April-May, southward return begins late August-early September in the interior, continues until freeze-up (Johnsgard 1987). Migrants arrive in the far north (northern Alaska) in late May or early June. In the southern part of the nesting range, breeding territories may be occupied as early as March.

Migrants move singly or in small groups, mostly by day. They move offshore, along continental shelf, inshore, and inland; loons breeding at Great Lakes migrate eastward to Atlantic coast and then southward to wintering areas along the southeastern U.S. coast. Typically they congregate on staging areas on large lakes following the breeding season and during fall migration.

Atlantic pathways are offshore, along the continental shelf from Nova Scotia to the Carolinas, and farther inshore, following the coast across Cape Cod (Powers and Cherry 1983). Band recovery data document inland pathways along a broad southeast/northwest front between the Atlantic Coast and central Canada, funneling primarily through Lake Michigan and Georgian Bay on Lake Huron (McIntyre 1988). Some birds migrate along a north/south line through the central U.S. to and from the Gulf of Mexico (McIntyre 1988). Loons breeding in Alaska and western Canada appear to move along the western edge of the Rocky Mountains en route to and from the Pacific Coast (McIntyre 1988).

Both adults and juveniles typically congregate on staging areas on large lakes following the breeding season (e.g., Bull 1974, McIntyre and Barr 1983, McIntyre 1988). Large concentrations also build on the Great Lakes and other inland lakes during the fall migration. Loons may linger on freshwater lakes until freeze-up before moving to maritime wintering sites (McIntyre 1988). The spring migration is direct and closely follows the northward retreat of ice (McIntyre 1988). Loons are diurnal migrants, and most flights, whether coastal or overland, appear to be initiated in the early morning (Williams 1973, Kerlinger 1982, Powers and Cherry 1983). The movements of juveniles during their three to four years as nonbreeders are not well understood. Most appear to remain on the coast, but some may move hundreds of miles northward, possibly tracking fish movements (McIntyre 1988).

Travel singly or in small flocks.

Loons eat fish and other aquatic animals, including crayfish, shrimp, leeches and some aquatic vegetation. Minnows are good-sized food for young, which also eat insects occasionally.

Loons are visual predators, locating fish by sight and diving deep to catch them. They generally hunt in water 2 to 4 meters deep. Because they rely on sight, clear water is critical to common loons. Adult loons ingest most of their food items underwater where they catch them. They bring larger items to the surface before eating them.

Loons drink water by scooping it up with their bill and tilting their head back in order to swallow.

Animal Foods: fish; insects; terrestrial worms; aquatic crustaceans

Loons eat fish and other aquatic animals, including crayfish, shrimp, leeches and some aquatic vegetation. Minnows are good-sized food for young, which also eat insects occasionally.

Loons are visual predators, locating fish by sight and diving deep to catch them. They generally hunt in water 2 to 4 meters deep. Because they rely on sight, clear water is critical to common loons. Adult loons ingest most of their food items underwater where they catch them. They bring larger items to the surface before eating them.

Loons drink water by scooping it up with their bill and tilting their head back in order to swallow.

Animal Foods: fish; insects; terrestrial worms; aquatic crustaceans

Primary Diet: carnivore (Piscivore )

Comments: Common loons dive from the water's surface, feed mainly on fishes; also amphibians and various invertebrates (Terres 1980). If nesting on a small lake, they may use an adjacent lake for supplementary foraging (Johnsgard 1987). In Ontario, loons attempting to raise young on a fishless acidic lake fed chick benthic algae and possibly benthic invertebrates but flew to other lakes to feed themselves (Alvo et al. 1988). Feeding occurs usually in waters less than 5 meters deep.

These loons are primarily piscivorous but are opportunistic and will eat any suitable prey they can readily see and capture (McIntyre 1988). 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 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.

Small fish mostly. Also feeds on crustaceans, aquatic insects, leeches, frogs, pondweeds and algae.

Common loons are provide food for their predators. They are also host to at least forty different body parasites. Most of these are cestodes and trematodes.

Adult loons have few known predators, but may be vulnerable to large marine mammals such as Enhydra lutris and large raptors, such as Haliaeetus leucocephalus and Pandion haliaetus. Larus, Corvus, Corvus, Haliaeetus leucocephalus  Procyon lotor, Mephitinae, Mustela, Chelydra serpentina and large fish are predators of loon eggs and chicks.

Loons avoid predation by nesting on islands, where ground-based predators are less common. When approached by a predator, loons sometimes attack the predator by rushing at it and attempting to impale it through the abdomen or the back of the head or neck.

Known Predators:

• gulls (Larus)
• crows (Corvus)
• ravens (Corvus)
• raccoons (Procyon_lotor)
• skunks (Mephitinae)
• minks and weasels (Mustela)
• snapping turtles (Chelydra_serpentina)
• large fish (Actinopterygii)
• sea otters (Enhydra_lutris)
• bald eagles (Haliaeetus_leucocephalus)
• osprey (Pandion_haliaetus)

Common loons are provide food for their predators. They are also host to at least forty different body parasites. Most of these are cestodes and trematodes.

Adult loons have few known predators, but may be vulnerable to large marine mammals such as sea otters and large raptors, such as bald eagles and ospreys. Gulls, crows, ravens, bald eagles  raccoons, skunks, minks and weasels, snapping turtles and large fish are predators of loon eggs and chicks.

Loons avoid predation by nesting on islands, where ground-based predators are less common. When approached by a predator, loons sometimes attack the predator by rushing at it and attempting to impale it through the abdomen or the back of the head or neck.

Known Predators:

• gulls (Larus)
• crows (Corvus)
• ravens (Corvus)
• raccoons (Procyon lotor)
• skunks (Mephitinae)
• minks and weasels (Mustela)
• snapping turtles (Chelydra serpentina)
• large fish (Actinopterygii)
• sea otters (Enhydra lutris)
• bald eagles (Haliaeetus leucocephalus)
• osprey (Pandion haliaetus)

Gavia immer preys on:
Paralichthyes albigutta
Strongylura marina
Leiostomus xanthurus
Actinopterygii
aquatic or marine worms
Crustacea
Insecta

Based on studies in:
USA: Florida (Estuarine)

This list may not be complete but is based on published studies.

Hectares of water area per territorial pair: 503 (New Hampshire); 44, 73 (Minnesota); 39 (Saskatchewan); 351 (New York) (Johnsgard 1987). Lakes smaller than 80 ha generally support only one breeding pair. Typically, territory size is larger on large lakes than on small lakes. Generally, loss of eggs to predators is not a primary cause of breeding failure (Johnsgard 1987). Wintering birds may defend feeding territories during the day, gather into rafts at night.

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).

Common loons use visual displays and vocalizations to communicate. Stokes and Stokes (1983) counted six different visual displays and five types of calls used by common loons. These calls and are used to attract mates, defend territory, signal danger and to communicate between flock members and family members.

Communication Channels: visual ; acoustic

Common loons use visual displays and vocalizations to communicate. Stokes and Stokes (1983) identified six visual displays and five types of vocalizations used by common loons. These displays and vocalizations are used in courtship, territorial disputes, communication between pairs and offspring, and between flock members, and to signal alarm.

Communication Channels: visual ; acoustic

Common loons are thought to be relatively long-lived birds. However, there is little information available about common loon survivorship. The oldest known wild common loon lived at least 9 years.

Range lifespan
Status: wild: 9 (high) years.

Average lifespan
Status: wild: 204 months.

Common loons are thought to be relatively long-lived birds. However, there is little information available about common loon survivorship. The oldest known wild common loon lived at least 9 years.

Range lifespan
Status: wild: 9 (high) years.

Average lifespan
Status: wild: 204 months.

Maximum longevity: 20 years (wild) Observations: While age at sexual maturity is unknown, it may take several years for young to begin breeding (http://www.dec.state.ny.us/).

Common loons breed once per year in the summer. They are thought to be monogamous, remaining with the same partner for life. Male and females arrive on the breeding territory together early in the spring. They establish a territory of 60 to 200 acres, which they patrol regularly. Common loons use physical displays and vocalizations to defend their territory and for courtship. For example, a loud yodeling call is used by males to let other males know that their territory is occupied. Following courtship displays, the male and female may swim to shore, where copulation occurs. To copulate, the male stands on the female's shoulders, with his head extended over and beyond hers.

Mating System: monogamous

Common loons breed once per year in the spring and summer, beginning at age 2 or 3. The male and female build a nest about two feet wide and made of soil, grasses, moss or plant matter. The nest is usually in a sheltered location near deep water so that the male and female can swim to and from the nest without being seen by predators. Nests are usually built on islands or peninsulas. When the nest is finished, the female lays 1 to 3 (usually 2) brown eggs, one to two days apart. The male and female both incubate the eggs, beginning after the first egg has been laid. Incubation lasts for 29 days. The first chick hatches up to a day before the others. They stay in the nest for a day or two after hatching, and then leave the nest with the parents. They spend the 2 to 3 months swimming around the territory with their parents, sometimes riding on the back of one parent. The chicks are able to dive short distances at two days old, and are able to fly at two to three months. Once they are able to fly, the young loons can become independent of their parents.

Breeding interval: Common loons breed once yearly.

Breeding season: Common loons breed in the spring, beginning soon after the ice covering the lakes breaks up.

Range eggs per season: 1 to 3.

Average time to hatching: 29 days.

Range fledging age: 1 to 2 days.

Range time to independence: 2 to 3 months.

Range age at sexual or reproductive maturity (female): 2 to 3 years.

Range age at sexual or reproductive maturity (male): 2 to 3 years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Average time to hatching: 28 days.

Average eggs per season: 2.

During incubation, male and female common loons take turns incubating the eggs and protecting the nest. After hatching, the chicks leave the nest with the parents. The parents feed the chicks whole food every hour from the time of hatching until they are up to three months old. They also protect the chicks from predators by vocalizing and swimming away from the predator to distract it from the chicks. Parents often carry the chicks on their back during the first few weeks of the fledging period. If the chicks are cold, a parent may return to shore with the chicks, where it shelters them under its wing. Chicks remain with their parents for up to three months, until they are able to fly.

Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

Common loons breed once per year in the summer. They are thought to be monogamous, remaining with the same partner for life. Male and females arrive on the breeding territory together early in the spring. They establish a territory of 60 to 200 acres, which they patrol regularly. Common loons use physical displays and vocalizations to defend their territory and for courtship. For example, a loud yodeling call is used by males to signal that their territory is occupied. Following courtship displays, the male and female may swim to shore, where copulation occurs. To copulate, the male stands on the female's shoulders, with his head extended over and beyond hers.

Mating System: monogamous

Common loons breed once per year in the spring and summer, beginning at age 2 or 3. The male and female build a nest approximately two feet in diameter of soil, grasses, moss or vegetation. The nest is usually in a sheltered location near deep water, allowing the male and female to swim to and from the nest undetected by predators. Often nests are built on islands or peninsulas projecting into the water. When the nest is completed, the female lays 1 to 3 (usually 2) brown eggs, one to two days apart. The male and female both incubate the eggs, beginning after the first egg has been laid. Incubation lasts for 29 days. The chicks hatch asynchronously, up to a day apart. They stay in the nest for a day or two after hatching, after which time they leave the nest with the parents and return to shore only rarely. The fledgling phase lasts 2 to 3 months, during which the young chicks accompany their parents around the territory, sometimes riding on the back of one parent. The chicks are able to dive short distances at two days old, and are able to fly at two to three months. Once they are able to fly, the young loons can become independent of their parents.

Breeding interval: Common loons breed once yearly.

Breeding season: Common loons breed in the spring, beginning soon after the ice covering the lakes breaks up.

Range eggs per season: 1 to 3.

Average time to hatching: 29 days.

Range fledging age: 1 to 2 days.

Range time to independence: 2 to 3 months.

Range age at sexual or reproductive maturity (female): 2 to 3 years.

Range age at sexual or reproductive maturity (male): 2 to 3 years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Average time to hatching: 28 days.

Average eggs per season: 2.

During incubation, male and female common loons take turns incubating the eggs and protecting the nest. After hatching, the chicks leave the nest with the parents. The parents feed the chicks whole food every hour from the time of hatching until they are up to three months old. They also protect the chicks from predators by vocalizing and swimming away from the predator to distract it from the chicks. Parents often carry the chicks on their back during the first few weeks of the fledging period. If the chicks are cold, a parent may return to shore with the chicks, where it shelters them under its wing. Chicks remain with their parents for up to three months, until they are able to fly.

Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

BRIEF SUMMARY: Egg-laying begins one to several weeks after spring arrival, usually during mid-May in the south, and well into June farther north. Replacement clutches may be initiated as late as early July. Incubation lasts around 4 weeks. Chicks leave the nest within 24 hours of hatching and are soon moved to nursery areas. Chicks may be carried on their parents' backs until they reach three weeks of age. Most juveniles are capable of flight at 11-12 weeks, and some leave their small, natal lakes or parental territories shortly afterward.

ARRIVAL AND TERRITORY ESTABLISHMENT: Timing of spring arrival is correlated with latitude and dictated primarily by ice-out phenology (McIntyre 1988). In southern portions of the breeding range, pairs may reoccupy territories in March, while at northern latitudes arrival may be delayed until mid or late May (McIntyre 1988). In Minnesota, an average of eight days elapsed between ice break-up and loon arrival in an early ice-out year, five days in an average year, and three days in a late year (McIntyre 1975). 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 chicks hatch and shrinking for failed pairs (McIntyre 1988).

COURTSHIP: It is believed that pairs remate each spring and that courtship serves primarily to renew the pair bond (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).

NESTING PERIOD: 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, usually during mid-May in the south, and well into June farther north (Palmer 1962, McIntyre 1975). Eggs are typically laid at two-day intervals (McIntyre 1975). Replacement clutches following failures of first nests are common (McIntyre 1975, 1988). Renests have been reported to occur within five days of a nest loss (Olson and Marshall 1952), but intervals of 10-14 days appear to be most common (Olson and Marshall 1952, McIntyre 1975, Sutcliffe 1980). Up to three laying cycles have been recorded in a season (Olson and Marshall 1952, McIntyre 1975). Nests lost early in the season are more likely to be replaced than those lost later (McIntyre 1988). Replacement clutches have been initiated as late as early July in Vermont (Kaveney and Rimmer 1989). If waters rise during incubation, loons continue adding to the nest's height to prevent flooding (McIntyre 1988). Replacement nests tend to have smaller outside dimensions (McIntyre 1975). Nest bowls are often reused in subsequent years, and occasionally within years for replacement clutches (Strong et al. 1987).

CLUTCH SIZE AND INCUBATION: Most clutches contain two eggs, and most one-egg clutches result from loss of the first egg (McIntyre 1975, Titus and VanDruff 1981). Three-egg clutches are very rare (Bent 1919, McIntyre 1988), and only two four-egg clutches have been reported (Nelson 1983, Zicus et al. 1983). Second eggs are smaller than first eggs, and eggs in replacement clutches are smaller than those in original clutches (McIntyre 1988). 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).

CHICK REARING: Chicks leave the nest within 24 hours of hatching and are soon moved to nursery areas (McIntyre 1988). In Saskatchewan, nurseries were located an average of 500 m from nest sites and occupied about 15 percent of territory size (McIntyre 1983). Both adults tend the young by feeding, carrying and defending them for several weeks. Chicks are carried on their parents' backs until they reach three weeks of age (McIntyre 1975). Although 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), they are fed largely by their parents until eight weeks of age (McIntyre 1988). 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).

NESTING SUCCESS: Breeding success varies considerably among populations. Most failures occur during incubation, from factors such as predation, flooding or stranding due to water level fluctuations, and human intrusion (Olson and Marshall 1952, McIntyre 1975, Wood 1979, Titus and VanDruff 1981, Rimmer and Kaveney 1988). In Ontario, lack of attempted breeding was associated with small, brown, low-alkalinity lakes; successful breeding associated with large, clear, high-alkalinity lakes; unsuccessful breeding resulted primarily from brood mortalities on acidic lakes, most likely due to shotage of suitable food for young (Alvo et al. 1988).

Chick survival is relatively high, especially after chicks reach two to three weeks of age (McIntyre 1988). However, Alvo et al. (1988) recently found higher mortality of older chicks on highly acidified lakes in Ontario, due to presumed starvation from an inadequate food base. Fledging success (percent of hatched chicks fledged) from a sample of 1,500 pairs across the breeding range averaged 80 percent (range = 67-94 percent ) (McIntyre 1988). Productivity (number of fledglings per pair) of this sample averaged 0.60 and varied widely between 0.22 for nine pairs in Minnesota (McIntyre 1975) and 0.97 for 132 pairs in New York (Parker and Miller 1988).

SITE FIDELITY: Appear to be faithful to breeding territories. Banded adults have been recaptured on the same breeding territory in subsequent years (McIntyre 1974, Yonge 1981, Eberhardt 1984). 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.

Breeds in solitary pairs near freshwater. First breeds at 2 years old. Both partners build the nest which is close to the water. 2 eggs laid, both partners incubate for 24-31 days. Both partners are involved in caring for young. Young can fly at 10-11 weeks old.

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 6 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

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Barcode of Life Data Systems (BOLDS) Stats
Public Records: 5
Specimens with Barcodes: 8
Species With Barcodes: 1

Common loons are threatened because their habitat is being destroyed. Loons are very sensitive to human disturbance, including recreation or development on their lakes. They are also threatened by pollution, such as mercury and other heavy metals that build up in the loons' bodies and slowly poison them. Acid rain is another pollutant that kills the aquatic plants and animals that many fish eat. This means that there are less fish for the loons to eat.

Oil spills are also deadly to loons. When loons become covered in oil, they are unable to fly, dive or swim. Loons can also be poisoned by accidentally eating lead fishing lures that are left in lakes and by getting tangled up in fishing nets.

Common loons are not federally endangered or threatened. However, they are specially protected in some states, including Michigan, where they are listed as threatened. They are also protected by the U.S. Migratory Bird Act.

IUCN Red List of Threatened Species: least concern

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: threatened

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2008
  Least Concern
• 2004
  Least Concern

Common loons are threatened primarily by habitat loss and/or degradation. Loons are highly sensitive to human disturbance through recreation or development on formerly secluded lakes. They are also threatened by industrial pollutants, such as mercury and other heavy metals that accumulate in the loons' bodies and slowly poison them. Acid rain kills phytoplankton, collapsing the aquatic food chains that loons depend on for food.

Oil spills are deadly to loons, which are unable to fly, dive or swim when their plumage becomes saturated with oil. Lead poisoning from ingestion of lead sinkers and entanglement in fishing nets are other sources of mortality.

Common loons are not considered federally endangered or threatened. However, they do have special conservation status in some states, including Michigan, where they are listed as threatened. They are also protected by the U.S. Migratory Bird Act.

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: threatened

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

United States

Rounded National Status Rank: N4B,N5N : N4B: Apparently Secure - Breeding, N5N: Secure - Nonbreeding

Rounded Global Status Rank: G5 - Secure

Acid rain and human disturbance are concerns, but there is no official conservation status for the species.

Global Short Term Trend: Relatively stable (=10% change)

Comments: In the heart of their breeding range, populations appear to be stable or increasing. Breeding Bird Surveys in Canada indicate a non-significant positive trend of 0.3 per cent annually, 1990-2000 (Downes et al. 2002). See Rimmer (1992) for details on status in northeastern U.S., where breeding populations in the early 1990s were stable or slowly increasing and wintering populations were variable but without a significant upward or downward trend.

Major Threats

Comments: Susceptible to human disturbance at breeding lakes (via development of shoreline areas and aquatic recreational activities), acid rain alterations of lake ecosystems, and mercury poisoning (USFWS 1987, Rimmer 1992; St. John, 1993). Also may be jeopardized in some areas by fluctuating water levels at the nest site and by increasing numbers of predators such as raccoons (Rimmer 1992).

HABITAT LOSS AND DEGRADATION: Direct and indirect effects of shoreline development may reduce the suitability of lakes for nesting. Although radical shoreline alteration and cottage construction appear to only rarely inhibit nest site selection, increased human activity around developments often does (McIntyre 1988, Sutcliffe 1980, Zimmer 1979). Hatching success decreased as the number of cottages within 150 meters of nests increased on lakes in central Ontario (Heimberger et al. 1983). McIntyre (1988) found that the number of lakes with territorial loons decreased with increasing shoreline development and recreational use in Minnesota between 1971-86. Water-level fluctuations resulting from human-made dams can also reduce the suitability of a lake for breeding. Fair (1979) documented nest abandonment and predation following lake drawdowns in New Hampshire. On Stillwater Reservoir in New York, McIntyre (1988) found that nests were lost to inundation when water levels rose more than 20 cm. Breeding loons in an area of regulated water levels in Minnesota had significantly lower productivity than other populations on naturally fluctuating lake systems (Reiser 1988). Nesting may be delayed by water levels that fail to recede after snowmelt (Fair 1979, Strong 1985). Although poorly regulated lake levels can lead to nest losses, creation of reservoirs has increased the availability of suitable nesting habitat in some areas (e.g., McIntyre 1988).

HUMAN DISTURBANCE AND HUNTING: Recreational pressures may have contributed to declines in some populations, but loons generally can acclimate to moderate recreational lake use. While Ream (1976) suggested that disturbance of nest sites by canoeists in the Boundary Waters Canoe Area in Minnesota was the primary factor limiting productivity, Titus and VanDruff (1981) later found few negative impacts from recreational activities in the Boundary Waters Canoe Area. Smith (1981) reported identical productivity on both remote lakes and on lakes with established canoe routes in Alaska. In Maine, no significant difference in breeding success was found for loons on high human-use versus low human-use lakes (Christenson 1981). However, densities may be lower on heavily developed than on relatively undeveloped lakes (McIntyre 1988).

When incubating loons leave nests because of disturbance, they may not return for an hour or more, leaving the eggs vulnerable to predation and cooling (McIntyre 1975, Titus and VanDruff 1981). Loons exhibit behavioral modifications in response to moderate recreational activity on many lakes. On high human-use lakes, loons flush at shorter distances (Smith 1981, Titus and VanDruff 1981), flush less readily and less vigorously, vocalize less once flushed, and return to the nest more quickly than loons on remote lakes (Titus and VanDruff 1981).

Motorboats may impact loons more negatively than canoes due to differences in peak use and breeding periods. On Boundary Waters Canoe Area lakes, motorboat use is heaviest early in the season, when loons are nesting, while canoe use peaks in August after the nesting season (McIntyre 1988). Loons are more easily able to avoid canoes than motorboats, and chicks are less likely to be separated from their parents by canoes. Motorboat wakes in combination with high water levels may cause nest destruction (Vermeer 1973).

Although the sport shooting that impacted populations around 1900 is now illegal, loons continue to be intentionally killed on occasion, primarily by sport and commercial fishers who consider the birds to be direct competitors (McIntyre 1988). Of 29 dead loons necropsied in New York from 1972-86, three had been shot (Okoniewiski and Stone 1987). Loons are still taken for food by American Indians and Inuits. In northern Quebec, the annual harvest ranges from 2,500-6,500 loons, most of them common loons (Desgranges and Laporte 1979). This harvest is thought to be too high to support the region's current population of 12,000 pairs.

COMPETITION: Intraspecific competition may limit productivity. Sibling aggression can be severe, especially during food shortages, and may result in the death of the subordinate, usually younger, chick (Dulin 1987). Chicks that wander into adjacent territories may be killed by neighboring adult loons (McIntyre 1988). Severe fighting by adults has been documented, presumably over territorial ownership, and can lead to injury or nest abandonment (e.g., Kaveney and Rimmer 1989). Competition with aggressive, non-native mute swans (CYGNUS OLOR) has been documented in Michigan (McPeek and Evers 1989).

ENTANGLEMENT: Mortality is known to occur from entanglement in monofilament sports fishing line and in commercial fishing nets (Vermeer 1973, Okoniewski and Stone 1987). Commercial fish traps and nets in the Great Lakes pose a serious, although unquantified, threat to loons (McIntyre 1986, 1988). Loons are also caught in nets used during coastal fishing operations (McIntyre 1978). Most mortality from these sources goes unreported.

ENVIRONMENTAL POLLUTANTS: Organochlorines and their residues have been detected in eggs and carcasses. DDE levels in tissue from Minnesota in the 1960s may have had adverse, sublethal effects (Ream 1976, McIntyre 1988). Eggs with higher levels of DDE residues tend to have thinner shells than eggs with lower residue levels (Vermeer 1973, McIntyre 1975, Sutcliffe 1978, Fox et al. 1980), although no studies have demonstrated evidence of shell breakage. There appears to be no documentation of lowered productivity as result of elevated pesticide loads (Fox et al. 1980), and organochlorine levels have generally declined in loon tissue in recent years (Frank et al. 1983).

Heavy metal contaminants may pose the most widespread, irreversible and deadly threat (McIntyre 1988). Methylmercury poisoning has been implicated in lowered productivity (Barr 1986) and winter mortality (Stroud and Lange 1983, Alexander 1985). Mercury is released into the environment during the operation of chlor-alkali and wood pulp plants, and through treatments of agricultural seeds (McIntyre 1988). Lake acidification may accelerate the release of mercury into the water column, hastening its uptake through the aquatic food chain (Barr 1986, McIntyre 1988). In Ontario, Barr (1986) found significantly higher mercury residues and lower successful use of territories in loons on lakes within 160 kilometers downstream of a chlor-alkali plant. High mercury levels in many necropsied loons following a large winter die-off along the Gulf Coast of Florida in 1983 (as many as 7,500 birds) (Alexander 1985) may have contributed to the emaciation and subsequent death of these individuals. In New York, Okoniewiski and Stone (1987) tentatively diagnosed mercury intoxication in three of 29 carcasses examined between 1972-86.

Other heavy metals, such as lead, cadmium and selenium, are actual or potential hazards (McIntyre 1988). Lead poisoning from ingestion of lead fishing sinkers is implicated as a cause of mortality (Locke et al. 1982, Okoniewiski and Stone 1987, Pokras and Chafel, 1992.

Acid precipitation may reduce the quality of nesting lakes. Alvo et al. (1988) monitored reproductive success on 68 small lakes (5.3-75 hectares) near Sudbury, Ontario that varied in pH from 4.0-8.4. Nesting success was higher on lakes with high alkalinity, which was negatively correlated with pH, than on low-alkalinity lakes. Unsuccessful breeding resulted primarily from brood mortalities on acidic lakes and appeared to result from lower prey fish densities. On acidified lakes in New York's Adirondack Park, chicks were fed prey much smaller or larger than those typically preferred (Parker 1988).

Oil spills pose a serious, although localized, threat to habitat. Most spills have occurred on marine wintering areas, and reports of mortality from coastal spills are common (McIntyre 1988). Spills on inland waters, particularly on staging grounds, could be disastrous to migrating loons (McIntyre 1988).

PREDATION: The major predators on nests and chicks include scavengers such as American crows (CORVUS BRACHYRHYNCHOS), common ravens (CORVUS CORAX), herring gulls (LARUS ARGENTATUS) and raccoons (PROCYON LOTOR), all of which have increased due to the proliferation of garbage dumps and other human refuse (McIntyre 1988). Raccoons caused 75-80 percent of nest losses on New Hampshire's two largest lakes in 1977 (Sutcliffe 1980). Other predators include snapping turtles (CHELYDRA SERPENTINA), northern pike (ESOX LUCIUS), muskellunge (ESOX MASQUINONGY), walleye (STIZOSTEDION VITREUM), red fox (VULPES FULVA), mink (MUSTELA VISON), skunk (MEPHITIS MEPHITIS), and occasionally other mammalian carnivores (Olson and Marshall 1952; McIntyre 1975, 1988). Otters (LUTRA CANADENSIS) and bald eagles (HALIAETUS LEUCOCEPHALUS) have been reported as possible predators (Titus and VanDruff 1981, McIntyre 1988). Harassment or disturbance by herring gulls, beavers (CASTOR CANADENSIS) and muskrats may lead to nest abandonment (Titus and VanDruff 1981). Predation on adults appears to be rare (Barklow and Chamberlain 1984, Riedman and Estes 1988).

DISEASES AND PARASITES: Susceptible to epidemics of both type C and type E botulism (McIntyre 1988). Type E botulism has killed up to 3,570 loons on Lake Michigan in a single year (Fay 1966, in McIntyre 1988), probably through ingestion of alewives during migration. Also susceptible to aspergillosis from airborne ASPERGILLUS spp. spores, which destroy the functioning of air sacs, particularly in stressed birds (Okoniewski and Stone 1987, McIntyre 1988). An extensive list of internal parasites has been documented (McIntyre 1988). Carcasses in emaciated condition from a massive die-off along the Gulf coast in 1983 had abnormally high numbers of microphallid trematodes (flukes), as well as tapeworms, spiny-headed worms, renal trematodes and renal coccidia (Stroud and Lange 1983). These parasites are believed to have caused hemorrhagic entritis and contributed to the pronounced emaciation of many dead birds. Loons are afflicted by a host-specific black fly (SIMULIUM EURYADMINICULUM), which may act as a vector and transmit a blood parasite (McIntyre 1975, 1988).

Restoration Potential: The ability to habituate to moderate levels of lakeshore and recreational use indicates that populations may continue to survive if suitable breeding, staging, stopover and wintering habitats are available. Loons are currently increasing in Vermont, New Hampshire and Massachusetts, and populations appear to be stable in New York and Maine. Just as human-induced habitat changes and recreational pressures probably caused the widespread declines noted prior to the 1970s, integrated management programs have contributed to the recovery in much of their northeastern U.S. breeding range. The potential for continued recovery is favorable (Rimmer 1992).

Preserve Selection and Design Considerations: Because of vulnerability to habitat loss or degradation, lakes that support breeding loons or serve as important migratory stopover sites need protection (Rimmer 1992). Identification and protection of known nesting areas is an important strategy because loons exhibit strong year-to-year fidelity to old nest sites (Strong and Bissonette 1985). When possible, two or three alternate sites with characteristics of preferred nesting areas (e.g., islands, deadwaters, marshes, protected coves) should be protected on each breeding lake. Small islands (< 5 ha) and deadwaters should receive complete protection from development. Undeveloped buffer zones of at least 150 m should be left on either side of mainland nest sites or deadwater entrances (Strong and Bissonette 1985). Shoreline areas adjacent to known traditional nursery areas should also be protected, with minimum undeveloped buffer zones of 150 m from both ends of the nursery (Strong and Bissonette 1985). Purchase of known nesting areas or suitable lakeshore breeding habitat by state or private conservation organizations, or acquisition of options to protect such lands from development (e.g., easements and zoning ordinances), may preserve loon nesting habitat (McPeek and Evers 1989).

Management Requirements: Protection techniques have focused on the breeding season and have involved primarily management of both habitat and people (Rimmer 1992). Loons have responded successfully to management by private conservation groups and state agencies. Most of the organizations that conduct statewide monitoring programs also coordinate management efforts.

CONTROL OF WATER LEVELS: Nest losses caused by flooding can be reduced by maintaining constant water levels during the peak nesting period (Fair 1979, Wood 1979), usually mid- May to mid-July in New York and New England. Rises in water level are more detrimental than drawdowns, and small drawdowns may be acceptable if distances between nests and the water's edge are not greatly increased (Strong and Bissonette 1985). In areas of recent flooding, all flooded timber should be cut and removed to minimize the amount of driftwood on shorelines (Strong and Bissonette 1985).

NESTING PLATFORMS: Artificial nesting platforms may improve nesting success on lakes that lack natural islands and have poor shoreline nesting habitat, fluctuating water levels, or a history of low productivity. Platforms rise and fall with water levels and can counteract extreme fluctuations on lakes where loons are not considered in water management plans (Wood 1979). Platforms have increased nesting success in Minnesota (McIntyre and Mathisen 1977), New Hampshire (Sutcliffe 1979, Fair 1989), Vermont (Rimmer and Kaveney 1988), and Massachusetts (Lyons 1987). Platforms alone are unlikely to induce nesting on unoccupied lakes or territories (McIntyre and Mathisen 1977, Sutcliffe 1979) and should not be used as mitigation to development or water level manipulation (Strong and Bissonette 1985). Plans for the construction of loon platforms are available from the North American Loon Fund.

PREDATOR MANAGEMENT: Predators can be the major cause of breeding failure in some areas. Removal of raccoons by hunting or trapping has met with some success in New Hampshire, but is labor-intensive and expensive (Wood 1979), and probably of only temporary benefit. Nesting platforms may reduce mammalian predation, which often increases after water levels drop (Fair 1979, Sutcliffe 1979). Improved methods of garbage disposal could reduce nest predation by crows, gulls, and raccoons, which are often attracted to human refuse (Hands et al. 1989).

FISH TRAPS: Mortality on the Great Lakes from commercial fishing operations could be reduced by using traps that open at the top to allow loons to escape and also by more frequently checking traps for captured loons. A cooperative program must be developed between commercial fishers and government agencies (McIntyre 1986).

PUBLIC EDUCATION: Human disturbance during the nesting and chick-rearing periods can be controlled in many ways. Activities such as boating, fishing, swimming, camping and picnicking should be prohibited near nest sites and in nursery areas. Closures of nest and brood-rearing sites through posting are recommended only in situations of heavy boat traffic where the closure can be reinforced through steady monitoring by law enforcement officials or volunteers (Wood 1979; J. Fair, pers. comm.). Interpretive signs posted at boat ramps, beaches, campgrounds and other public access points should inform recreationists about the natural history and conservation needs of loons. The number of visitors to wilderness areas could be restricted and specific travel routes established. Visitors could be required to attend an educational program before entering a recreational area with breeding loons (Titus and VanDruff 1981). No camping should be allowed on small islands, and other uses should be discouraged (Titus and VanDruff 1981) or, if necessary, prohibited. Boat engine horsepower limitations or speed limits should be established on smaller breeding lakes or in designated areas of large lakes.

Informational brochures, posters, press releases and other educational paraphernalia should be produced and distributed (Strong and Bissonette 1985, McIntyre 1986). Educational programs, including filmstrips and slide lectures, should be presented to schools, lake associations and other groups. Personal contacts with lakeshore residents should be established and maintained. Monitoring by volunteers may be especially important on lakes with relatively low human use where the presence of law enforcement officials may not be feasible. Involvement of volunteers in lake patrols and population surveys may stimulate public interest and reduce levels of human disturbance.

Management Research Needs: The North American Loon Fund annually provides small grants to researchers studying a diversity of topics on loon biology, behavior and conservation. A list of current and past projects that have received funding, as well as grant application guidelines, can be obtained by contacting the fund.

Wintering Distribution and Ecology. Detailed information on the precise wintering distribution and abundance is lacking. Little is known about the distribution of discrete breeding populations, the ecological requirements and social structure of wintering loons, the relationship between adults and juveniles, causes and rates of mortality, the impacts of environmental contaminants or oil spills, the effects of weather, the impacts of commercial fishing, the site preferences of individual loons or different age and sex classes, and the mobility of loons during winter. In addition to research addressing these topics, monitoring programs such as a coordinated coastal winter watch or midwinter aerial survey should be initiated.

More information is needed on migration routes and staging areas in spring and fall. Little is known about the habitat and feeding requirement during migration, the residence times of individuals on staging areas, the effects of weather or human disturbance on migrating loons, and age and sex differences in the timing, route selection and ecology of migrant loons. Coordinated migration watches should be conducted at strategic coastal and inland sites.

Studies are needed on the life history of juveniles between fledging and their return to northern lakes. Little is known about their ecological needs and habitat use, diet, migration routes, wintering distribution, movements during their two or more years as nonbreeders, causes and rates of mortality, social relationships and behavior, age at which the definitive alternate plumage is acquired, age at first breeding, and degree of philopatry to natal lakes.

Research is needed on the energetic requirements of adults and young, recruitment patterns of young and nonbreeders into breeding populations, effects of intraspecific competition on breeding status and success, site fidelity and territory turnover patterns, duration of pair bonds, and patterns of lake colonization or recolonization.

Levels of chemical contaminants in adults and eggs should be monitored on a regular basis. Studies should attempt to determine the biological consequences of chemical and heavy metal toxification so that discharge practices can be modified if necessary. Monitoring should be continued on the effects of lake acidification on breeding loons.

Studies should be undertaken to quantify and assess the impacts of entrapment in commercial fishing nets and traps.

Research is needed on the causes of type E botulism and how outbreaks can be prevented or minimized.

The answers to many important questions on loon movements, behavioral ecology and demography require the banding and marking of individual birds. The development of improved capture methods is essential. Protocols must be designed for individually marking discrete populations on both the breeding and wintering grounds. Feasibility studies should be initiated to design and test radio transmitters that can be used on loons (Rimmer 1992).

Needs: Coastal wintering areas need protection from the damages of oil spills (Rimmer 1992).

Because common loons eat fish, they are viewed by some people as competition for fishermen.

Common loons are a source of food to the Cree Indian tribe of Canada. They were once hunted for sport, and are now an important symbol of wilderness to many people.

Positive Impacts: food

Because common loons eat fish, they are viewed by some people as competition for fishermen.

Common loons are a source of food to the Cree Indian tribe of Canada. They were once hunted for sport, and are now an important symbol of wilderness to many people.

Positive Impacts: food

Stewardship Overview: Nest on islands or backwater areas on lakes with adequate fish prey. Pairs typically raise one or two chicks, but failure is common and compensated sometimes by renesting. On the northern breeding grounds in Canada, populations appear to be stable or increasing. However, at the southern edge of their range in the Northeast, breeding loons have gradually drawn northward in the past century. Many types of disturbances threaten loons at their breeding sites, including lakeshore development, human recreational disturbance, predation, fluctuating water levels at nest sites, entanglement in fishing gear, environmental pollutants, and loss of prey due to acidic rain. Identification, monitoring and protection of nest sites in areas of human use are essential to the continued nesting success. Wintering areas along the Pacific and Atlantic coasts also require protection from the damages of oil spills. More information is needed about wintering areas, distribution, and numbers (Rimmer 1992).