Usefulness
of birds
Birds are very useful as destroyer of pests. A big proportion of
birds' diet consists of insects (and their larva), including many that are
highly injurious to man. A large number of birds feed on rodents and mice, both
very destructive for farmers all over the world. Vultures, Crows, Kites and
Egrets feed on carrion and waste in garbage dumps. These birds play an
invaluable part in keeping our environment clean and disease-free.
Birds are also an important food source for humans. The most
commonly eaten species is the domestic chicken (a descendant of the Red
JungleFowl and its eggs, although geese, pheasants, turkeys and ducks are
also widely eaten. Other birds that are used for food include partridges,
grouse, quails, pigeons, emus, ostriches and doves. Along with bees, birds such
as the Purple Sunbird, are important pollinating agents. Birds as seed
dispersers, play an essential for the propagation of many species of trees and
plants. Other examples include Homing pigeons to carry messages, Falcons for
hunting and Cormorants for fishing. Chickens and pigeons are used in
experimental research in biology and comparative psychology.
Many species have become extinct through human activities
like excessive hunting, logging, large scale use of insecticides and pesticides
in agriculture and industrial pollution. Two birds that have become extinct in
India in the not too distant past are Mountain Quail and the Pink-Headed
duck.
Numerous species have
come to depend on human activities for food and are widespread to the point of
being pests. They have adapted well to the rapid urbanization and growth in
human population. For example, the House Crow and Rock Pigeon thrive
near human habitation in large parts of the world. While in addition to these
two species, the Common Myna,Bank Myna and Black Kite are thriving in
India; Vultures (Aegypiinae) and the House Sparrow are facing an
inexplicable decline in their population.Shumpei Kitamura:Seed dispersal consists of the removal and deposition of seeds away from parent plants. Because seeds are not mobile, their movements must be facilitated by dispersal agents such as gravity, wind, water or animals. Numerous plants in the tropics have seed-dispersal mechanisms that are associated with animals (Fig. 5). Therefore, fruit-frugivore interactions, in particular seed-dispersal processes, are considered to greatly affect plant demography in the tropics. Even in central Southeast Asia where the wind- and gravity-dispersed family Dipterocarpaceae dominates the plant community, animal-dispersed plant species diversity is still high and most forest birds and mammals eat at least some fruits. Consequently, the relationships between fruits and frugivores are extremely diverse, and both animal-dispersed plants and frugivorous animals are dominant within their respective groups in tropical forests.
Read more:http://news.mongabay.com/2010/0425-hance_kitamura.html#ixzz1vOQRyRpu
