Migration of Birds
Classification of Animal Chordates of Class 11
Some of the birds have the habit of changing their habitats periodically between two locations, alternating in direction with a view to secure optimum conditions for breeding and feeding. The migration is from their permanent area (breeding ground) to the feeding place (resting place) and again back to the permanent place.
The birds which migrate are known as migratory birds whereas which do not migrate are known as resident birds.
Types of migration
On the basis of direction
Longitudinal migration : The birds migrate from southern hemisphere to east-west direction or from mountainous parts to plains during summer and return to the mountains in winter e.g., Patagonian Plover.
Latitudinal migration : (also known as vertical migration). The birds migrate from plains to hills or from tropical parts to north temperate and sub-Arctic regions, for breeding and nesting but during winter they retire to south for shelter e.g., Common woodcock, Bush chat, etc.
On the basis of period of migration
Birds of passage : These birds may be seen thrice a year for a short time on their way to colder or warmer countries in spring or autumn.
Summer visitors : These birds migrate from warmer southern parts to comparatively colder northern parts for breeding and nestling and return southwards to their natural home in late summer or autumn, e.g., Cuckoo.
Nidifugous (Precocial) and Nidicolous birds
Newly hatched young of birds are of two types:
Precocial or Nidifugous : fully clad with down feathers, have bright eyes, able to feed and run after the parents e.g., poultry birds.
Altricial or Nidicolous : naked, blind, weak and need greater parental care. e.g., sparrow, crow, penguin, etc.
POINTS TO REMEMBER
The chirping of birds at the evening time is known as roosting.
Largest egg of bird-Struthio : 1.5 Litre capacity.
Smallest egg of bird : Mellisuga (Humming bird).
Largest bird-Struthio camelus : 8 feet height, 300 Lbs weight.
Largest sea bird : Diomedea epomorphora (Royal albatross), wing stretch 200-375 cms.
Smallest bird : Mellisuga helenae 5.5 cm long.
Fastest Swimmer bird : Pygoscelis papua (Penguin)
Deepest Diver bird : Aptenodytes forsteri (Emperor Penguin).
Fastest Runner bird : Struthio - 80 km/hr. speed.
Heaviest bird of prey : Vulture gryphus.
Second largest bird is Emu (Dromaeus) as is most primitive living bird.
Recently extinct bird is Dodo (Passenger birds) of Mauritius.
Incubation period of Hen’s egg at 102°F (38.8°C) 21 days.
Though polygamy is common in birds, but Emu is strictly monogamous.
Penguins are flightless birds found in Antarctica, wings are paddle-like, act as flippers during swimming and are covered by scale-like feathers.
T.H. Huxley said “birds are glorified reptiles”. The feathers are highly modified reptilian scales. Birds have scales on their legs. Their eggs resemble reptilian eggs in general and have a calcareous shell.
Among the Indian birds, the sun birds are probably the smallest.
Dove is the emblem of the sign of peace.
The humming bird is the only bird which can fly backward as well as forward.
The Bursa Fabricii is a blind sac with much lymphoid tissue in the cloaca of some young birds. It produces lymphocytes (a type of white blood corpuscles). It is also called “cloacal thymus”.
Colombia has the world’s richest diversity of birds.
Uropygium (tail) : the projecting terminal portion of a bird’s body from which the tail feathers arise.
Nidology : study of nests of birds.
Swifts use saliva for binding nest materials.
Humming birds build the smallest nests.
Bald Eagle has the largest nest.
Flightless birds - Kiwi, Emu, Rhea, ostrich, cassowary, tinamus
Kiwi lays the largest egg in proportion to its own size.
Himalayan Bearded Vulture is the largest Indian bird. Previously the Sarus was considered the largest Indian bird.
Ostrich has the largest eyes of any land animal.
Kiwi is the only bird known to use the sense of smell for finding food on the ground.
Indonesia has the most bird species facing extinction.
Red Billed Quelea (Quelea quelea) of Africa is the most abundant bird. Previously the house sparrow was considered the most abundant species of birds.
Europe is the only continent where there are no parrots today although their fossils have been found.
Jatinga is a village in Assam where a mass suicide of birds occurs.
Why does the owl need to rotate its head through an angle of 270°? Because its eyes do not rotate in their sockets. Each eye is fixed like a car headlight.
Ostriches are beneficial to Zebras because ostriches act as lookouts for Zebra herds, warning them of approaching danger.
Copulatory organ (true penis) is present in ostrich, duck, swan and goose.
Famous Indian Ornithologist - Dr. Salim Ali.
National bird - Pavo cristatus (Pea cock)
Eggs of certain birds are coloured due to presence of ooporphyrin and oocyanin pigments.