Water: It is essential for life. Where there is mpore water, more organisms are found there . availability of water in a habitat can greatly influence its organisms. Migration: Another factor that changes the size of populations of a habitat. When a few individuals come to an area , it increases the size of the population in that area. organisms migrate in search of better living places.
Habitat changes can take a large number of forms. The wildlife manager will be mainly concerned with how habitat change will affect wildlife populations. Changes to habitats will cause changes to food supply, changes to migration patterns and stress in wildlife populations. These things can have profound effects on wildlife populations.
The type of habitat alteration directly affects the type of influence it has on the wildlife there – whether it be altered breeding cycles, age structure of the population, animal health, etc.
Physical Changes
Physical changes to habitats include destruction and reduction in habitat. One thing that many people do not think about is a reduction in the size of habitat due to fragmentation of a natural area. When a natural area becomes fragmented or even just divided, it can have a big impact on both the vegetation and wildlife in the area. Vegetation in fragmented areas has weedy edges, and the altered microclimate can cause changes in the vegetation composition. These changes alone can impact animals. In small fragments, there may not be enough resources such as food, shelter and nesting sites to support a viable population of animals. If animals are migratory, fragments can prevent the animals from moving in their traditional way. Wildlife corridors and road crossings have been experimented with as a way to link fragments and decrease division - but with mixed results.
Biological Changes
All over the world, there are examples of unwanted species – such as possums and deer in New Zealand, foxes and rabbits in Australia, and cats in many other countries. The introduction of new species into an ecosystem can have profound effects on wildlife. Introduced species can actually displace native species by taking over their role in the ecosystem; compete with native animals for resources, or simply predate upon native species.
Sometimes, wildlife managers will intentionally introduce an exotic species so that it will have some beneficial impact on the ecosystem. This is known as biological control. For example, the North American Screw Worm fly has been a pest in cattle grazing areas in the past. Scientists introduced sterile male flies into the ecosystem, knowing that the female flies only mate once. The male flies mated with the female flies, who then did not reproduce – thus the population dropped dramatically. Introducing individuals from outside can actually have a beneficial effect on the ecosystem.