The loons belong to family Gaviidae and of order Gaviiformes. They are the size of a large duck or small goose. There are 5 species found worldwide and only 2 species are found in Pakistan. Following are the names of species found in Pakistan
- Black-throated Loon (Gavia arctica)
- Great Northern Loon (Gavia immer)
- Black-Throated Loon
Species: G. arctica
Binomial name : Gavia arctica
Subspecies : G. a. arctica
G. a. viridigularis
The Black-throated Loon (Gavia arctica) is a migratory aquatic bird. They have a grey head, black throat, white underparts and chequered black-and-white mantle. Non-breeding plumage is drabber with the chin and foreneck white. Its bill is grey or whitish and dagger-shaped. In all plumage a white flank patch distinguishes this species from all other divers including the otherwise almost identical Pacific Diver. Breeding adults are 58 to 77 cm (23 to 30 in) in length with a 100 to 130 cm (39 to 51 in) wingspan, shaped like a smaller, sleeker version of the Great Northern Diver Body mass is reportedly from 2–3.4 kg (4.4–7.5 lb) .
Black-throated Loon is a specialist fish-eater and catching its prey underwater. It feeds on fish, insects, crustaceans and amphibians. It flies with neck outstretched.
The calls include a yodeling high-pitched wail and harsh growls, similar but lower pitched than Pacific Loon.
- Great Northern Loon
Species: G. immer
Binomial name : Gavia immer
The Great Northern Loon is one of the five loon species that make up the genus Gavia, the only genus of the family Gavidae and order Gaviiformes.
Adults can range from 61 to 100 cm (24–40 inches) in length with a 122–152 cm (4–5-foot) wingspan.The weight can vary from 1.6 to 8 kg (3.6 to 17.6 lbs). On average a Great Northern Loon is about 81 cm (32 inches) long, has a wingspan of 136 cm (54 inches), and weighs about 4.1 kg (9 lbs). Breeding adults have a black head, white underparts, and a checkered black-and-white mantle. Non-breeding plumage is brownish, with the chin and fore neck white. The bill is black-blue and held horizontally. The bill colour and angle distinguish from other species.
The female lays 1 to 3 eggs on a hollowed-out mound of dirt and vegetation very close to water. Both parents build the nest, sit on the egg or eggs, and feed the young.
Great Northern Loon is a specialist fish-eater, catching its prey underwater. Freshwater diets consist of pike, perch, sunfish, trout, and bass; salt-water diets consist of rock fish, flounder, sea trout, and herring. It is small sea-duck which is black-and-white in color which swims and dives for fish. They may dive as deep as 200 feet (60m), occasionally staying submerged for several minutes at a time.
The bird needs a long distance to gain momentum for take-off, and is ungainly on landing. Its clumsiness on land is due to the legs being positioned at the rear of the body: this is ideal for diving but not well-suited for walking. When the birds land on water, they skim along on their bellies to slow down, rather than on their feet, as these are set too far back.
The loon swims gracefully on the surface, dives as well as any flying bird, and flies competently for hundreds of kilometers in migration. It flies with its neck outstretched, usually calling a particular tremolo that can be used to identify a flying loon. Its flying speed is about 120 km/h (75 mph) during migration. Its call has been alternately called "haunting," "beautiful," "thrilling," "mystical", and "enchanting"
Great Northern Loon nests are usually placed on islands, where ground-based predators cannot normally access them.When approached by a predator of either its nest or itself, divers sometimes attack the predator by rushing at it and attempting to impale it through the abdomen or the back of the head or neck.