Thanks
Andy. I simply feel there are a number of statements that have been made that need some simple hard facts to accompany them. Here’s just a few...
Science puts forward hypotheses to test ideas. A good scientific hypothesis is both testable and based on extensive observations. The term “hypothesis”, and also “theory”, is often used to describe ideas, particularly generalisations, which individuals have generated. This usage does not meet the rigorous criteria required in scientific endeavour. So it must not be accorded the characteristics of same.
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I am not too sure that humans have been causing extinctions from when we first “popped up”, whenever that is meant to be, but there seems little doubt that with their use of fire, hunting weapons and traps, that some populations were hunted to extinction through prehistory. The expected (‘natural’) rate of extinction is 1 to 2 species per year. With current global clearing of remaining rainforest it is estimated that the current rate is at least hundreds times the natural rate and quite likely thousands of times greater.
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The statement: “We cause extinctions just by existing” is both uninformative and technically incorrect to me. I feel it is important that people do have some clear idea of how human activities contribute to declining populations and ultimately extinction. The following list is not exhaustive...
- Direct degradation or total destruction of natural habitat is a major one. Massive land clearing for agriculture, from the wheat belt to the coastal beef and dairy farms, orchards and fruit and vegetable plantations. Urbanisation. Damming rivers for water supplies. Irrigation and loss of arable lands due to salt. Burning areas more frequently or more than occurs in nature.
- Exploitation of natural resources such as forestry, mining and fishing. Use of clear felling, over harvesting of fish stocks and certain mining techniques or failure to implement appropriate environmental safe guards.
- Introduction of exotic plants and animals. Animals introduced for food and/or other products, such as grazing stock, alter the plant species composition of areas and the binding of soil, so in conjunction with stock with hard hooves facilitate soil erosion. We have already mentioned predators and competitors. Invasive exotic plants reduce the biodiversity of areas where they establish. Exotic pests and diseases are also introduced by foreign imports, although legal imports are subject to quarantine in an attempt to eliminate this risk.
- Human activities produce pollution that affects the air, soil and water, including the oceans e.g. oil slicks, dumping of toxic wastes.
- Accelerating climate change through use of fossil fuels for producing power, transport and petrochemicals.
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Australia has had over 20 mammals go extinct in the last 200 years. It is believed nearly all were the result of a combination of predation by foxes and cats and grazing competition with stock and rabbits. Foxes (1845 on) and rabbits (1859 on) were released for hunting. Thomas Austin, first to release 24 rabbits on his property, is recorded as saying: "The introduction of a few rabbits could do little harm and might provide a touch of home, in addition to a spot of hunting." Cats were kept as passengers on ships in order to control rats and mice that would otherwise spoil food stores. Between shipwrecks and their similar use to protect colonists’ food stores, feral cat colonies had become established in the wild by the 1850s.
Given that the knowledge, understandings and attitudes we have today did not exist then, were these extinctions really avoidable by forethought? The releases involved plenty of forethough, much of it by accmplished intelligent individuals.
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Australia is currently facing another potential wave of extinctions. There are 15 frogs, 16 reptiles, 44 birds, 35 mammals and 531 plants on Australia's endangered species list. Professor Corey Bradshaw, director of the Environment Institute's Climate and Ecology Centre at The University of Adelaide, says Kakadu National Park has suffered a 95 per cent decline in mammals. He stated: “The Great Barrier Reef has been suffering biodiversity declines for decades. Now if we can't get it right in our two biggest and most well-known and certainly the best-funded parks and protected areas in Australia, what hope have we for the rest of our national parks?" I would make additional note that the Oenpelli Python and the Arnhem Land Skink are also in trouble, based on the lack of recent sightings and difficulty in locating specimens where they were once common place. The skink has not been sighted in two years.
These losses are occurring in natural habitat. They are happening NOW. There is nothing in the scientific literature that I can locate which talks about either a doomsday scenario for reptiles or a timeline of a couple of centuries.
Blue
Haha
