When you hear the term "invasive species" you might think of a plant like the Kudzu - the vine that covers the southern US, draping over trees to generate an eerie peaked landscape and blanketing entire forests. Or the icky zebra mussel that clings to manmade structures so well that it clogs industrial water intakes. The Asian long-horned beetle that has munched through the forests of North America does not have many friends, even among animal lovers.
Can something this cute really be an invasive species? source: http://lol-rofl.com/wild-rabbit-habitat/ |
But what about the adorable bunny? There is no Australian equivalent to the European bunny. Bunnies introduced to Australia by Europeans have been ravaging the Aussie countryside for over a century.
Australians call this a "plague of rabbits" Source: http://www.pir.sa.gov.au/biosecuritysa/nrm_biosecurity/pest_animal/pest_animal_programs/european_rabbits |
When Europeans established penal
colonies in Australia in 1788, they brought European culture, including an
affinity for rabbit farming and sport. Starting
in 1859, the Acclimatisation Society encouraged the release of rabbits into the
wild so that settlers could enjoy rabbit hunting (Crisp 2009, Kerr 2008) unaware
that they had started one of the fastest colonization of any invasive species. By 1900, the rabbits had almost spread across the entire continent. By 1950, their population had grown to 600 million. Despite reductions in
population due to disease, rabbits still outnumber humans 13:1 and have significantly
impacted ecosystems throughout Australia (Crisp 2009,
Kerr 2008, DEC NSW 2005). Recent efforts
to halt or reduce rabbit population growth have failed as the rabbits continues
to grow in number (Zuckerman 2009.
Negative Impacts of Rabbits Invading Australia
Despite their cuteness, rabbits have devastated the native ecosystems of Australia through:
• overgrazing
• reduced plant biodiversity
• promotion of non-native plants
• suppression of trees and shrubs with resulting cascading
ecosystem impacts
• increased competition with native herbivores
• increased prey for introduced cats and foxes (Cooke 2012)
• food shortage in Australia
• financial crises for Australian farmers (Zukerman 2009)
The Causes
The spread of rabbits across Australia
can be traced to failures in science, policy and management.
Scientific research provided several biological
control agents that directly reduced the population (Cooke 2012). However, experiments have not been well
controlled, resulting in the accidental early release of a lethal virus into
rabbit populations before experiments had been completed. This early release prevented coordination of
the subsequent dip in population with corresponding management decisions as
well as the release of the disease at a suboptimal time in terms of rabbit life
cycle (Kerr 2008). Biological control is
one of the more cost-effective ways of reducing populations, but even very
lethal viruses will leave some survivors who are resistant to future infection
(Zukermon 2009). The best tactic is to time
biological agent release with other factors and efforts.
Public policy has improved since the
deliberate release of 24 rabbits by the Victorian Acclimatisation Society in
1859 so that settlers would feel more 'at home' (DEC NSW 2005). By 1901, a special Royal Commission meeting
decided on an aggressive rabbit-proof fencing project. But recently, these fences have fallen out of
favor. The Queensland Government disbanded the Board responsible for the last
serviced rabbit proof fence in the country, stretching 555 km to protect 28,000
km of farm land (Crisp 2009).
Inconsistent policies have allowed rabbits time to surge back and thwart
long-term management capacity.
Management failures are more difficult
to pinpoint. The failure of the
rabbit-proof fencing project in 1900-1907 is most likely a failure of management
since the effort had sufficient political will from the Royal Commission . The Commission stated with urgency, "to ensure rapidity of construction, the
contractor [is to] be bound to simultaneously start operations with one party
working north from the railway line … another party working south from the
railway line, a third party working north from Fitzgerald Inlet, and other
parties from any other convenient starting points" (Crawford 2001?). Unfortunately, by the time the fences were
completed, the "rabbits had already moved into the
areas being fenced off." (Zukerman 2009).
This appears to be a time when an adaptive approach would have helped so
that the managers could make decisions on the spot while watching the expansion
of rabbit populations.
The Aftermath
Today, populations are surging again
and the efforts of science, policy and management must coordinate to address
the problem (Williams et al. 1995).
From the scientific realm, a new
biological agent would jumpstart population reduction. Also, gaps in knowledge hinder effective
rabbit population control, in particular, questions of how predators, diseases,
and resource availability interact (Robley et
al. 2004).
Gosling and Mintzberg's five mindsets
of a manager help to frame the management approach (2003). In the reflective mindset, it is important to
take time to understand the system, evaluate past failings, and be sure to ask
the right question. The analytic mindset
helps to understand the circumstances under which widespread rabbit eradication
is possible. Read et al. says it
takes proper timing, sustained effort over time "significant long-term
planning, resources, commitment and dedication" (2011, 52). The worldly
mindset can identify the context that best lends itself to eradication, such as
the optimum scale and the amount of resources needed for long-term impact. The collaborative mindset keeps track of
public opinion and involvement as well as political will. The action mindset ensures that the project
avoids "paralysis by analysis" (Sunstein 2002) and stays nimble
(Meadows and Marshall 2001).
There
is no central information agency with standards for population data and
tracking (Zukermon 2009).
Political support is needed to provide
long-term funding for both management and scientific research (Robley et al. 2004).
Conclusion
What is most needed to address rabbit
populations in Australia is higher coordination between scientific discovery,
legislative support, and management techniques reduce populations and keep them
low. A central repository of scientific
knowledge coordination, management that follows the five mindsets and
consistent political support would go a long way in addressing this issue.
References
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