Partial Migration: Unique Feature Of Birds

Migration is a unique feature of animals and long distance migration is the characteristic feature of birds. According to Salewski and Bruderer (2007) migration is the regular, endogenously controlled, seasonal movement of birds between breeding and non-breeding areas. Although it is a dangerous but it is a necessary journey essential for the completion of various bio-ecological cycles. Fortunately, they are well equipped to survive the task and bring winged enjoyment back to birder's yards year after year. Migration continues to be a widespread phenomenon, with more than half of the world’s approximately 10,000 species of birds classified as migrants (Berthold 1998). However, the percentage of bird species that exhibit migratory behavior

It may be divided into various types on two definite basis – I. Nature of migration II. Nature of bird I. Nature of migration – Migration is the long distance travel by the birds for various purposes. It can be further divided into following types – A) Complete migration – The migration of entire group from one place to another for particular purpose is called complete migration. The distance covered may be hundreds or even thousands of kilometers. The arctic tern (Sterna paradisaea) is an example of a complete migrant. B. Partial migration – The large group when divides into smaller groups for migration is called partial migration. Partial migration is the phenomenon which spares the ecological load. e.g Robins of England show partial migration. Other partial migrant birds are passerine and shorebirds.etc. C. Differential migration – The migration of entire group of the same species at different time and also at different places is called differential migration. Such migration is often based on age, sex or both. Ex-