The underparts are pure white, but have some black on the undertail coverts and vent. [22] In contrast, in the Gulf of Alaska, adults of both sexes reportedly averaged 4.13 kg (9.1 lb). [97], This bird is central to the plot of the children's novel Great Northern? The preceding courtship is very simple, with mutual bill-dipping and dives. [26], A juvenile often has a dark, brownish-grey nape that may look darker than the pale-edged black feathers. This is because it has a large range – more than 20,000 km2 (7,700 sq mi) – and because it has a stable population trend that does not warrant a vulnerable rating. [66] A male that occupies a new territory appears to alter its yodel to be clearly distinguishable from the call of the previous territory owner. Furthermore, males average up to nearly 27% more massive than females in some populations. The adult winter plumage is attained between October and January by partial moult mainly of head, body and tail feathers. [92] In addition, artificial floating nesting platforms have been provided for the common loon in some lakes to reduce the impact of changing water levels due to dams and other human activities. The estimated breeding population ranges from 1,400 to 2,600 mature individuals in Europe. A long-bodied, low-slung diver. [45] (Hence, most adult loons have two or more different mates during their lives.) [57] The eggs are about 88 mm (3.5 in) long and 55 mm (2.2 in) wide[32] and the two eggs are laid with an interval of one to three days between them,[40] and hatch asynchronously. [51] Significantly more nesting sites are found on islands than on mainland shoreline. [16], A number of fossil loon species are known from the Pliocene, and specimens from the Pleistocene of California and Florida appear to represent a paleosubspecies of the common loon. [18], Chicks may be killed by common snapping turtles, large gulls, bald eagles and large fish such as northern pike and largemouth bass. [60] Juveniles leave the breeding ground before ice formation in the fall, weeks after their parents. Common Loon Gavia immer Range map Data ... Common Loon Gavia immer. It is used in the establishment of territorial boundaries and in territorial confrontations, and the length of the call corresponds with the loon's level of aggression. ", "Graded frequency variations of the tremolo call of the common loon (, "Male common loons signal greater aggressive motivation by lengthening territorial yodels". [63], Considerable information on longevity and survival rates has been collected in the past two decades, owing to the implementation of an efficient capture protocol that permits marking and monitoring of large study populations. The adult common loon can range from 66 to 91 cm (26 to 36 in) in length with a 127 to 147 cm (4 ft 2 in to 4 ft 10 in) wingspan, slightly smaller than the similar yellow-billed loon. [36][37] In the east, several thousand winter along western European coasts, probably originating from Iceland, Greenland, and Canada. [2], The common loon is an expert fisher, catching its prey underwater by diving as deep as 60 m (200 ft). [19] It has a skeletal structure made up of a number of solid bones (this is usual for the Gaviiformes and penguins[25] but unlike most flying birds which have bones with extensive pneumatization, hollow and filled with air to make the lighter), which adds weight but helps in diving. Loons from the Great Lakes region migrate to the Gulf of Mexico or Florida coasts. Common Loons migrate from northern lakes to coastal ocean waters. Common Merganser. [83], Elevated levels of mercury have been associated with changes in foraging as well as brooding behavior among adult common loons, especially in higher concentrations. Hunt Jr, G. L., Drew, G. S., Jahncke, J., & Piatt, J. F. (2005). [86] Studies have deduced that elevated levels of mercury in the blood of common loons have detrimental effects on brood productivity. [76], Botulism, acquired by eating infected fish, can lead to paralysis and drowning. [99] An old colloquial name from New England was call-up-a-storm, as its noisy cries supposedly foretold stormy weather. [62], The tremolo call—sometimes called the "laughing" call—is characterized by its short, wavering quality. [97], The common loon appears on Canadian currency, including the one-dollar "loonie" coin and the previous series of $20 bills. [93] The common loon abandons lakes that fail to provide suitable nesting habitat due to shoreline development. They swallow most of their prey underwater, where it is caught, but some larger items are first brought to the surface. This preference is based on two lake attributes: size and pH. [19][20] Sizes vary regionally, especially by body mass, with the smallest bodied loons on average from lower-central Canada and the Great Lakes, while westerly birds are similar or mildly larger, and loons breeding further east can appear to be significantly larger. [77] Outbreaks sometimes lead to thousands of deaths. [60][61], The common loon produces a variety of vocalizations, the most common of which are the tremolo, the yodel, the wail, and the hoot. [52] Breeding pairs patrol their territories routinely, even at night,[53] defending the territory both physically and vocally. Checking their bird book, they believe that these are great northern divers. It is more difficult to separate from the yellow-billed loon, but its breeding plumage has more white markings on the neck and the squares on its shoulders are usually smaller; the non-breeding plumage has darker neck-sides contrasting more sharply with pale areas and bill colour. [2] They migrate in the day, starting about two hours after sunrise and flying at altitudes of 1500 to 2700 m above sea level, above the convective and turbulent layer of air. They overwinter on the ocean but spend most of their time on the freshwater lakes and ponds where they breed and raise their young. One such study found that brood productivity was reduced by half when female blood mercury levels exceeded 4.3 μg/g and productivity completely failed when female blood mercury levels exceeded 8.6 μg/g. [100] Some old Scottish names such as arran hawk and carara are corruptions of old Scottish Gaelic onomatopoeic names representing the bird's call; others, like bishop and ember goose, were used to avoid older names for this sometimes ill-omened bird.

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