• This goat wants to eat all your endangered plants. Image by Paul O'Donnell / CC BY 2.0 (Flickr)Source: Flickr
Goats are wreaking havoc in Oregon - but Australia knows only too well what happens when you introduce animals that don't belong in your ecosystem.
By
Rebecca Shaw

4 Mar 2016 - 12:18 PM  UPDATED 4 Mar 2016 - 12:18 PM

If you were asked to write down facts about goats, what is the first thing you would come up with?

Likely appearing high on the list would be the popular belief that goats will eat absolutely anything, especially if it resembles plant matter. But it seems that the people in charge of running the city of Salem in Oregon have not heard that widespread goat fact, according to a report recently submitted by Salem’s public works department.

The report described an ambitious project, launched by Salem last October, to hire a team of 75 goats to eat through invasive plants such as Armenian Blackberry and English ivy, which were choking the native vegetation in the 23-hectare Minto-Brown Island Park.

The plan backfired when the goats began to do what goats do best. They went off-track, eating native plants alongside the invasive species, and chewing on tree bark for good measure.

The project ended up costing the city almost US$21,000 (including the cost of removing the blackberry canes the goats didn’t eat). That's more than five times the amount it would have cost to hire a person in a Bobcat unit to do the same job.

Oregon council members should not feel bad - this is not the first time an introduced species has wreaked havoc on native land, as Australia knows all too well.

The spread of the red fox

The European red fox (Vulpes vulpes) was introduced to Australia in the 1800s for the purpose of recreational hunting in Victoria. Within 100 years, the foxes had spread to most of Australia.

They are a serious threat to biodiversity in Australia, becoming the main predator to certain native wildlife, and has played a big role in the decline in numbers of some birds and animals such as the bilby and the black-footed rock-wallaby.

The Government has an entire 'threat abatement plan' to coordinate Australia's response and try to fix the problem caused by just this species alone. 

Cane toads let loose
A cane toad, probably waiting to breed

80 years ago, cane-growers were worried about the damage that cane-beetles were doing to their crops, so an entomologist called Reginald Mungomery had the idea of bringing in toads to eat the grubs. Problem solved, right? Well, not quite.

Approximately 101 cane toads were initially released around Cairns and Innisfail, and within one week the toads had started laying eggs, with hatching occurring just three days later.

The toads turned out to be very bad at controlling the cane pests, but highly successful at reproducing and releasing poison from their bodies - without natural predators to thin the numbers, we now have an extensive toad problem on our hands. There are millions of cane toads spreading throughout Australia’s northern landscape, and moving westward at an estimated 40 to 60km per year.

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Macquarie Island overrun

Macquarie Island, located about halfway between Australia and Antartica, has been through a lot. In the 1800s cats were introduced to the island, with the introduction of rabbits following 60 years later.

The grazing habits of the rabbits began to have destructive effects on the native vegetation, so in the 1960s they were controlled using the Myxoma virus. The vegetation recovered, but this meant the cats had fewer rabbits to eat, so they began eating the native seabirds instead.

To protect the seabirds, the cats were then eradicated, and that was when the rabbit population exploded once more. After major pest eradication projects, the island was finally declared pest-free only in 2014, but the sorry tale is used as a lesson for conservation agencies, reminding them that risk assessments should be comprehensive.

Indian Myna - major problem
Indian Myna

We've probably all seen these bullies of the sky, terrorising birds and humans alike. The Indian Myna (Acridotheres tristis) was introduced to Australia in the... yes, 1800s - to help control insects, and has grown to become one of the biggest threats known to native birds.

Mynas are aggressive, chasing away other birds, and are even known to defecate in other bird's nests and to go so far as to throw competitor chicks out of nests.

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Rabbits breeding like rabbits
Wild Rabbit (Agriculture Victoria)

For over 150 years, rabbits have been a problem in Australia. This can be blamed on a man named Thomas Austin from The Victorian Acclimatisation Society, who had the idea in 1859 to release 24 wild rabbits to hunt for sport and to make settlers "feel more at home".

If they felt at home amongst 10 billion rabbits, the project was a success – rabbit population numbers hit that target less than 70 years later.

During their spread from Victoria to New South Wales to Queensland to Western Australia, they have caused soil erosion, the loss of billions of dollars to the agricultural industry, lead to local extinction of various trees, and in turn had an effect on other native wildlife numbers.

Although biological methods such as the Myxoma virus have drastically reduced rabbit numbers, there is still an estimated 200 million rabbits in Australia, and they are here for the foreseeable future.

One million camels

Camels were first introduced to Australia in the 1840s to assist with the exploration of inland Australia. It is estimated that between 10, 000 to 20, 000 camels were initially imported, with numbers reaching an estimated one million camels before culling began in the late 2000s.

Camels are sort-of our version of goats - they cause broad environmental damage, feeding on 80 per cent of the available plant species (including rare and threatened flora), damaging wetlands, and competing with native animals for food and shelter.

There have been recent renewed calls for culling of the remaining camels, with some farmers calling for action to keep numbers under control. 

Really, the Salem council could have just consulted us before deploying those goats.

The obvious lesson to take from 19th century Aussies is that introducing species is a very risky endeavour, and should not be undertaken lightly - no matter how many plants you want goats to eat.