In recent years there has been an increased desire to acquire greater familiar with the term “Wildlife”. In a broad sense, wildlife means plants and animals in their wild state, embracing all living organisms.
In the earliest stage of civilization, wildlife was a source of fuel, tool, food, clothing etc. but at that time more or less an equilibrium was maintained between man and the ecosystem. As man became more and more civilized, his needs gradually increased. With the help of modern technology, man started to extract the resources of ecosystem carelessly and continuously, without having any idea upon its consequences. Thus the relationship between man and ecosystem started to change rapidly, resulting in the deterioration of the quality of the wildlife and quality of the human life.
Nowadays people are realizing that the global problems like global warming, climate change, famine, sea level rising, deterioration of quality of air, flooding, acid rain, major habitat loss etc. are mainly or truly due to the destruction of the ecosystem by human activities.
Why to conserve?
Wildlife is the greatest heritage and in many ways more important than the temples and historic buildings, because, unlike these man-made structures, if once destroyed wildlife can never be restored. At present, wildlife facing several threats by human activities and very little is left. If the destruction continues in the current pace then our future generations could miss the majestic beauty of the wildlife. If all animal life cease to exist, thus how dull would life be? For better quality of human life conservation effort must be taken before it is too late. This, in essence, is the crux of wildlife conservation.
Various food chains and cycles constitute the life support system which is essential for the survival of wildlife. Any major alteration in any one of these, results in serious disturbance in the balance of nature and may threaten very existence of man himself on this planet.
There is an ever increasing demand by all of us for the better quality of life. We must not lose sight of our specific conservation activities for which efforts to solve the major problems have to be succeeded, and succeed they must, our more finely focused activities might have helped to ensure that the brave new world continues to be populated by creatures which have fascinated us, provided for us and shared this planet with us over the millennia.
Over proliferation or destruction of a species is not good for the global environment. If individuals of a species increases in numbers then there is increase in the need for food and other resources. This increased demand for food and other resources will affect the other species ' survivability in the world. Even though, disappearance of species is a normal process but it should be in a gradual manner and at a constant rate. If one species disappear, other living things may take the role of that species and maintain the biodiversity. There will be chances for the evolution of new species from the old germplasm. The evolution of new species requires conducive environment. Mutation and variation are major factors for the appearance of new species. Dramatic changes in the environmental factors (Global warning, absence of rain, storm, earth quake, falling of celestial bodies on the earth, volcano explosives, increase of sea level etc) will facilitate destruction of most species. Those species having higher adaptability to the extreme environmental changes can only able to survive for some more period of time.
Several extinction events were recorded by scientists that occurred during prehistoric life time. The extinction rate that occurred during the past extinction events is closer to the extinction rate of certain endangered species of today.
Extinction events
If human population increases throughout the world at a higher rate, habitat destruction will be higher, and destruction of several species at higher extinction rate will be expected. At higher population density there will be competition for wealth and resources among humans. This competition makes the people to extract resources as much as possible from the environment. Loss of habitat and essential resources make the wild life become extinct. At one time all the resources available in the earth may be completely used by human. Because of technological development humans may survive by adapting alternative ways (renewable energy, electric vehicles, synthetic materials and products, H2 fuel, atomic energy etc). These alternative ways might help only the wealthy and technologically developed nations. The people from the poor nations will be under threat, because they would be forced to spend lot of money to satisfy only the basic requirements.
Alternative ways may indirectly affect the global environment and may cause dramatic changes (Global warming, larhe scale melting of glaciers, destruction of plant kingdom, disease outbreak, etc.) These factors may destroy human life considerably on the earth. Finally human beings may not find happy and cheerful life on the earth. People all over the world want nothing more than a better life for themselves and their families. Somehow we must redefine our quest for a better life. A better life, a high-quality life, means living with nature, not apart from nature. As thinking creatures of the earth, our prime way is going with the nature and we have to protect the nature in order to make the earth suitable for the survival of the next generation.
The current crisis
Species are not immutable, they appear, persist for a time, and then disappear, a process to which the fossil record bears ample testimony.
Species can be lost either through extinction, in which all individuals die out living no progeny or through pseudo extinction, in which a lineage evolves over time or diverges into two or more daughter lineages.
The world appears to be experiencing an extinction event comparable in magnitude to many of those indicated in the fossil record. Current and predicated future extinctions are much higher than the estimated natural (or) back ground levels. Most extinctions appear to be caused either directly or indirectly by human population.
Past extinction events
The fossil record indicates the extinctions occurred in a few, relatively short (as measured on the geological time-scale) intervals, known as “extinction events”. From the start of Cambrian period, 580 million years ago, to the present day, five major extinction events have been documented, in the late Ordovician, Devonian, Permian, Triassic and Cretaceous periods. The most severe was in the late Permian, 245 million years ago, when the number of marine animal families decreased by 54 %, and marine animal species may have declined upto 96 %. The process of evolution took about 50 million years to regain the number of families lost during the Permian mass extinction. The most famous is the extinction of the late cretaceous, 65 million years ago during which dinosaurs became extinct and mammals achieved dominance in terrestrial communities.
There is some evidence that the late cretaceous extinction event was associated with an extra-terrestrial impact, an instantaneous event in geological terms.
Background extinction rate
A very coarse estimate of the ‘Natural” or background rate of animal extinction prior to human-influence is 2.5 species per million years, calculated as,
Estimated total number of species (approximately around 10 million described and not described vertebrates and invertebrates)
Extinction rate = ------------------------------------------
The average persistence time (around four million years).
Recent extinction rates
There are more species on earth at the present geological time than in any other period. As a result of human activity, the current rate of extinction of species is greater now than at any time in the past. Known extinction since AD 1600 is concentrated amongst certain taxa. Although vertebrates constitute only approximately 2.5 % described animal species, they account for around 50 % of known extinctions. The majority of these are two scientifically best known taxa, mammals and birds.
The recent documented extinctions in these two taxa are 10-15 times more than expected. If these rates of extinction were to continue, all birds and mammals would be lost in just 30,000 years.
Extinctions among other vertebrate taxa are not as conspicuously high as for birds and mammals, but as a group vertebrates have still experienced five times more extinctions than predicted from the estimated background extinctions rate. Conversely, for an invertebrate group except molluscs fewer extinction have been documented than predicted.
Some 1.4 % of recognized mammal species and 1.3 % of birds are known to have become extinct, compared with only 0.3 % of molluscs and 0.017 % of insects. In total, 0.5 % of described vertebrates and 0.002 % of invertebrates have become extinct since AD 1600.
Invertebrates : Vertebrates
Mollucs-191 species : .Birds-122 species
.Insects-59 species : .mammals-60 species
------ : ------
Total 250 : 182
------- : ------
Although there are actually fewer known vertebrate extinctions than invertebrate extinctions, vertebrates have expected 25 times more extinctions while considering the proportion of extinct species with the total number of known species.
The extinction rate for birds and mammals was about one species every 10 years during the period 1600-1700, but it rose to one species every year during the period 1850-1950. This increase in the rate of extinction is an indication of the seriousness of the threat to biological diversity. Many species are not completely extinct and persist only in very low numbers. Those species may be considered “ecologically extinct”, in that they no longer play a major role in community organization. About 2 % of the world’s remaining bird species and 5 % of the mammals are in imminent danger of extinction, if present threat to their existence is not halted.
Future extinction rates
A number of authors have made prediction about present and future extinction rate based on estimates of habitat loss coupled with assumptions derived from bio-geography.
The number of species remaining in a reduced area of habitat is calculated from the species-area relation, in which
S = CZA
Where, S = number of species
A = Area
C and Z are constants. Value of Z depends on the type of species involved, climate and geography of the area of consideration.
The most widely quoted generalization is that the loss of 90 % of a habitat results in the loss of half the species present.
Bio Diversity
The variety of living organisms considered at all levels of organization including the genetic, species and higher taxonomic levels and the variety of habitats and ecosystems as well as processes occurring there in.
Causes of Extinction
The major threats to existence of wildlife or biodiversity are habitat destruction, habitat fragmentation, habitat degradation, (including pollution), the introduction of exotic species, the increased spread of disease, and over exploitation of many species for human use.
These threats to biological diversity are all caused by an ever increasing use of the world’s natural resources by the expanding human population. The greatest destruction of biological communities has occurred during the last 150 years, during which the human population went from 1 billion in 1850 to 5.3 billion in 1990, and increasing at higher rates in recent years.
People use natural resources and convert vast amounts of natural habitats into agricultural lands and residential areas, so the population growth itself is partially responsible for the loss of biological diversity.
Habitat Destruction
The most important means of protecting biological diversity is habitat preservation. In many countries of the world, particularly on islands and where human population density is high, most of the original habitat have been destroyed.
Rainforests, tropical dry forests, wet lands and aquatic habitats, mangroves, and grasslands are the major habitats destroyed severely by human activity.
Habitat fragmentation
This is the process whereby a large, continuous area of habitat is both reduced in area and divided into two or more fragments. Fragmentation may limit a species potential for dispersal and colonization. It reduces the foraging ability of animals. Many animal species, either as individuals or social groups, need to be able to move freely across the landscape to feed on widely scattered sources. Species confined to a single habitat may be unable to migrate over their normal home range in search of that scarce resource.
Habitat fragmentation may cause population decline and extinction by dividing an existing widespread population into two (or) more sub populations. These smaller populations are then more vulnerable to inbreeding depression, genetic drift and other problems associated with small population size.
Habitat degradation
Biological communities can be damaged and species driver to extinction by external factors that do not change the structure of dominant plants in the community. For example, in temperate deciduous forests, physical degradation of a habitat might be caused by frequent uncontrolled ground fires; these fires might not kill the nature trees, but the rich perennial wildflower community and insect fauna on the forest floor would be gradually eliminated.
Pollution
Pesticides
The dangers of pesticides were brought to world attention in 1962 by Rachel Carson’s influential book “Silent Spring”. The central thesis of this book was that DDT and other organochlorine pesticides which are used on crop plants to kill insects and sprayed on water bodies to kill mosquito larval, were finding their way up the food chain and harming wildlife. Birds that ate large amount of insects, fish or other animals exposed to DDT frequently concentrated the pesticide in their tissues. Birds with high pesticide levels tended to lay eggs with abnormally thin shells, which cracked during incubation. As a result of failure to raise young, populations of these birds particularly raptors (pray) such as hawks and eagles showing dramatic declines throughout the world, (Use of pesticides is banned in some of the countries).
Water pollution
Water pollution often severely damages aquatic communities. Rivers, lakes and oceans are used as open sewers for industrial wastes and residential sewage. Toxic wastes released in aquatic environment can diffuse over a wide area and be actively carried by currents. Toxic chemicals even at low levels can be concentrated to lethal level by aquatic organisms. Species that feed on aquatic species are exposed to the concentrated levels of toxic chemicals. High concentration of nutrients in river or lake or pond water by release of human sewage, fertilizers etc will result in the development of thick “blooms” of algae at the water surface. These algal blooms may outcompete other plankton species and shade out bottom dwelling plant species. Without oxygen much of the remaining like dies off and removed from that eco system.
Air Pollution
The air that surrounds the terrestrial environment has become contaminated and altered by human activities.
Acid rain
Industries such as coal and oil fired power plants release large quantities of nitrates and sulfates, which combine with moisture in the atmosphere to produce nitric and sulfuric acid. These acids become part of cloud systems and dramatically lower the PH of rain water. As the acidity of water increases by acid rain, many fish either fail to spawn or die. The acidity also inhibits the microbial process of decomposition, lowering the rate of mineral recycling and ecosystem productivity.
Ozone
Automobiles, power plants, and other industrial activities release hydrocarbons and nitrogen oxides as by-products of the burning of fuels in internal combustion engines. In the presence of sunlight, these chemicals react with the atmosphere to produce Ozone and other secondary chemicals producing photochemical smog. Although Ozone in the upper atmosphere is important in filtering out harmful UV radiation, high concentrations of Ozone at ground level damage plant tissues and make them brittle.
Toxic metals
Industrial activities release large quantities of lead, Zinc, mercury, cyanide and other toxic metals into the atmosphere. These compounds are directly poisonous to plant and animal life.
