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MOVING AWAY FROM CHANGES
Migration and translocation are two different types of movement of species. Migration is the seasonal or periodic movement of animals due to changes in climate or food availability, or to ensure reproduction. It is generally a round-trip – moving from one area to another and then back again. However, some trips may take a lifetime to complete! For example, various species of Pacific salmon born in freshwater streams, travel to ocean waters, and then return to the stream where they were born to breed before dying. Translocation, on the other hand, is the movement of species from one area to another by people. There are three types of translocations:
 Tanushree: Sometimes, it happens accidentally. Say, when people and goods travel internationally. For example, three species of rat – the Black, Norway and Polynesian – have spread to most of the world as hitchhikers on ships. But often, people shift species intentionally for various reasons like… Why translocate? Translocation has various advantages like – Introduction of new species into an area may have benefits like economic development, improvement of hunting and fishing, ornamentation, or maintenance of cultures by incoming settlers in the area. But, the most important reason is conservation of endangered species. When a certain species becomes extinct due to human activities, over-collecting, over-harvesting, or habitat deterioration, the species is re-introduced for restoring the habitat. For instance, zoological parks play an important role in the re-introduction of captive-bred animals into the wild. Restocking, on the other hand, is done where populations have dropped below critical levels, and cannot be naturally recovered. Say, in populations with slow reproductive rates or inbreeding. Populations of some endangered species become so small that they lose genetic variation. To avoid extinction, individuals from related sub-species or populations are introduced for genetic restoration (recovery to a normal level of genetic variation). Flip side However, translocation, especially introduction of new species into an area, is a highly debated topic. Generally, the damage done by introductions far outweighs their benefits to biodiversity. Even the reviews of translocation projects of birds and mammals suggest that the success rate is low. The chances of getting exotic pathogens in the species, which may cause various diseases, are quite high. But, the biggest fear is that of invasion by the alien species. Invasion Once alien species enter a new location, they establish a breeding population, and spread throughout the new area. They compete for limited resources or prey on the native species. They may even hybridise with them. This may lead to a decline and even extinction of the native species. Their invasion can
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