That we humans have a dismal record exterminating other species is clear, but less well known is the Great Dispersal. We have carted vast numbers of plants and animals around the globe to places they don't belong. It's a long list, including foxes, rats, pigs, prickly pear and European wasps. These are both facets of the new geological epoch called the Anthropocene.
Every continent has been affected by introduced species, but few more than Australia. Some are accidental, but some are deliberate. Among them are one of our favourite travel mates, the cat. They're compact, companionable and they eat vermin. This makes them an ideal passenger on long ship voyages.
Aboard his ship, the HMS Reliance, Matthew Flinders had a cat named Trim. It won his affection by climbing up a rope after falling overboard. Together they circumnavigated Australia on the HMS Investigator. Later they were shipwrecked when The Porpoise struck Wreck Reef in 1803.
Trim's survival skills show what a hardy creature they are. It's prescient because it gives a clue to how cats fared when they arrived in Australia.
Cats originated in West Asia and first became attached to humans in ancient Egypt. Evidence suggests our association may go back even further, to 9500 years ago where a co-burial site has been unearthed.
Cats most likely first came to Australia about 200 years ago during European settlement. Research on their genetics suggests they arrived at coastal sites around 1820. By 1890, they had achieved the remarkable feat of colonising most of central Australia. It took them only 70 years to establish over an area of 7.6 million square kilometres. It appears they originally spread westwards from Sydney, and eastwards from Perth.
Since then, their numbers have been joined by domestic cats, and there are few parts of the continent, and even the surrounding islands, where they are absent.
Cats are well adapted to the Australian environment. They do not require free water when live prey are available. They are agile and stalk prey. Where food is plentiful, such as around tips, there can be as many as 700 to 2000 cats per square kilometre. Typical densities in natural environments are less than one per square kilometre, the number varying greatly in arid environments between boom and bust conditions.
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