Biodiversity

Biodiversity is a magic word which conjures up different images to anybody who enjoys the outdoors whether actually, or virtually via TV and print media. The dazzling colours and shapes of the Great Barrier Reef can be appreciated easily whether on a TV screen or through the glass of diving goggles or a glass bottomed boat. Similarly, you don’t have to visit Madagasgar to marvel at its unique plants and animals. The lemurs of that island tend to have a fascination for most of us, even if we have never seen them for real.

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The ducks with the dark heads in this image are Freckled ducks, once classified as a threatened species, their status has improved but they are still protected.

Australia’s dismal extinction record

Australia’s record for animal extinction gives us the unenviable reputation of being the per-capita king of wiping out species. How can so few people on such a vast continent wipe out so many species in such a short time?

What drives species to extinction?

The explanation is simple and should already be obvious if you read the page on deforesation. The quickest and simplest way of wiping out a species is occupying its land and this is exactly what we did in Australia. But it wasn’t humans who occupied the land and drove various wallabies, reptiles and bird species to extinction, it was our livestock. Humans occupy just 1.5 million of the 770 million hectares of the land area of Australia, their crops occupy another 24 million with plantation timber being another couple of million. But our sheep and cattle graze close to 400 million hectares. It is your choice of food and clothing that determines your contribution to the extinction of species in Australia.

 

But what about cats, and foxes, and rabbits. Surely, they had a hand in the extinctions? The short answer is … “yes, but not much”. The long answer is found in careful work by scientists. A study published in 2003 demonstrated how wrong the common myths of feral animals wiping out our wildlife. The study looked at 145 species of marsupials and considered the various factors that could have reduced their range … including of course some who were extinct. They considered the overlap of the habitat of the animals with sheep and with foxes and rabbits. They considered the size of the animals (were they the right size to be fox prey), the diet, the type of habitat, the rate at which the animals reproduce and so on.  They applied some high powered statistics to work out the most important factors influencing the decline or extinction of these marsupials. The most consistent factor predicting a decline in the species population wasn’t foxes, or rabbits, but the overlap with the sheep population. Australia’s sheep population is now about 70 million, but back in 1990 it was 170 million. Even before 1900, sheep were eliminating species as they spread out across the continent. By 1895, the Australian yearbook records 90 million sheep and 11 million cattle.

How to minimise habitat loss?

The way to prevent species extinction is not to occupy their habitat. Some species can deal with human and livestock intrusion, but many cannot and will perish. Minimising our occupation of wildlife habitat is the simplest way to do the least damage to wild populations. Occupation of wildlife habitat is almost entirely dependent on our choice of foods. Consider, for example our use of forests for timber. We have 2 million hectares of plantations and about 17 million hectares of other forests which we use. While we should aim to minimise our intrusion into non-plantation forests, the 2 million hectares of plantation is an unavoidable consequence of being alive. Using less paper and recycling can reduce the size of that 2 million hectares, but it is small to start with. But the vast area occupied by sheep provides just 3% (no that’s not a misprint) of Australia’s food intake (by Calories), cattle provide another 4.5% with about 2/3 of cattle production being for export. By contrast, wheat provides as much protein in the Australian diet as sheep and cattle combined and the amount of land used for the production of wheat for local human use is smaller than the area used to grow wheat for chickens, pigs, sheep and cattle. These considerations make the outcome of the careful work of the scientists obvious. Habitat destruction is the major cause of wildlife decline and extinction and the major influence on habitat destruction is the choice of what you eat.

Put simply, if you want to minimise your destructive contribution to biodiversity loss, then you will minimise your animal food intake.