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The Enemies of
Butterflies
1
- Predators
2
- Parasites, Parasitoids & Pathogens
3 - Human impact - habitat destruction
Human impact
A few
centuries ago, when the human population on Earth was smaller and
less affluent, mankind required less land and consumed far less of
the planet's resources. Enough contiguous wild habitat existed to
ensure that butterflies could move easily between their breeding
sites. Since then the human population has grown and has become
increasingly wasteful and greedy. Wild places have consequently
diminished in size and become increasingly fragmented and isolated.
Shrinking habitats mean smaller butterfly
populations. As breeding sites become smaller and more isolated, gene
interchange reduces to insignificant levels. Butterflies then lose
their adaptability and become become dependent on highly localised and
specialised habitats. The isolated populations of
Papilio machaon in England e.g. can only
now survive at a handful of flooded Norfolk fenland sites, whereas in
mainland Europe where habitats are larger and less isolated, the
species breeds over a very wide area and utilises a broad range of
habitat types.
Habitat destruction across the world is caused
almost entirely by human activity. Urban
expansion has the greatest impact, but governmental policy on farming,
forestry and road planning also has a very profound effect on the
distribution and abundance of butterflies.
The destruction of the rainforests
In
excess of 10000 square miles ( 2.6 million hectares ) of Amazon
rainforest is deliberately burnt down every year to clear land for
soya and oil palm plantations. The notion that vegetarianism is
beneficial to wildlife is utterly absurd, as wonderful rainforests
that support billions of animals and plants are wantonly destroyed,
burnt down and replaced with these lifeless and sterile plantations.
Amazon rainforest, Brazil, yesterday
Amazon rainforest, Brazil, today
Soybean plantation, former Amazonian
rainforest, Brazil © Paulo
Fridman/Corbis
In addition to the gargantuan areas of land destroyed to make way for
plantations, vast expanses of forest are devastated by slash and burn
farming. This normally occurs on a smaller scale as it is carried out
by small farming communities rather than by multi-national companies.
Nevertheless it accounts for the loss or severe degradation of many
thousands of sq kms of rainforest every year. Land which once
supported 750 species of trees, 1500 species of flowering plants, 500+
species of birds and perhaps 1000 species of butterfly, is cleared to
make way for cattle ranches. The bounty is short-lived however. The
resulting pastures are poor in nutrients, and only capable of
supporting cattle at very low densities. The pastures are burned
annually to promote new grass growth and to destroy cattle parasites.
The fires rage uncontrolled, devastating vast areas of land. The
deforested land is much hotter and drier than the rainforests -
consequently the average temperature of the entire region rises and
the humidity falls dramatically. This causes major changes in the
vegetation structure of the remaining areas of forest, leading to
reduced biodiversity even in protected areas.
Please
support rainforest conservation :
sign
on-line petitions
reduce
consumerism
reduce your mileage
boycott tropical hardwoods
boycott South American beef
boycott oil palm products
support eco-tourism
support
rainforest conservation organisations
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