This video resource examines how koalas have adapted to their new suburban environment, and how that environment is attempting to adapt to koalas.
- What do the Amazon basin and Queensland, Australia have in common? What is the driving force behind this? Which do you think is more important—the needs of human populations or the need to conserve natural habitats and protect the species which live in them? How would you propose striking a balance between the two?
- What are some of the hazards faced by koalas in the suburban habitats in which they now find themselves living?
- Are large highways impassable for koalas? How did scientists learn the answer?
- What measures are Australian authorities taking to protect koala populations from cars? Are they working? How do they know?
Despite being one of the most recognizable and beloved icons of Australia, the koala is a threatened species. Although the exact size of the current koala population is unknown—ranging from several hundred thousand to as few as 43,000—what is clear is that environmental trends are all working against the species, which once roamed freely across eastern Australia.
As is so often the case, the primary threat to the species has been human activity. The koala population never recovered from the early 20th century, when millions of koalas were hunted and trapped for their fur. Laws have since been passed throughout Australia prohibiting the harming of koalas, or even ownership of them as pets. Today, the main threat from humans is far less intentional, but far more difficult to stop: land development.
It’s a story familiar to anyone who’s followed the plight of bears, wolves, and many other formerly wild animals whose natural habitat has been cleared and converted into an ever-growing mass of suburban sprawl. Koalas are especially vulnerable as their habitat is restricted to their single food source: eucalyptus gum trees. Koalas require large expanses of healthy, connected eucalyptus forest in which to travel in search of new mates to maintain their genetic diversity. As Australia’s suburbs have expanded over the course of the past century, 80% of its eucalyptus forests have been cleared and partitioned by roads, isolating koala populations in ever smaller and more crowded pockets of “bush.” This isolation in itself presents a serious problem, as increasingly inbred koala populations have proven highly susceptible to sexually transmitted diseases like chlamydia—symptoms of which have been noted in 50% of the koala population of the Australian state of Queensland.
Although individual humans generally regard their furry new neighbors with affection, their suburban environment presents challenges like traffic accidents and dog attacks with which koalas are ill-equipped to contend. Having identified cars as the number one killer of koalas—accounting for over one third of all deaths—Australian authorities have begun planting eucalyptus trees on highway overpasses, building highway underpasses along identified corridors of koala travel, and establishing protected habitats where koalas can live without the hazards of modern human conveniences.
Life Science – Content Standard C
As a result of their activities in grades 9-12, all students should develop understanding of:
- Interdependence of organisms
- Living organisms have the capacity to produce populations of infinite size, but environments and resources are finite. This fundamental tension has profound effects on the interactions between organisms.
- Human beings live within the world’s ecosystems. Increasingly, humans modify ecosystems as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening current global stability, and if not addressed, ecosystems will be irreversibly affected.
- Behavior of organisms
- Organisms have behavioral responses to internal changes and to external stimuli. Responses to external stimuli can result from interactions with the organism’s own species and others, as well as environmental changes; these responses either can be innate or learned. The broad patterns of behavior exhibited by animals have evolved to ensure reproductive success. Animals often live in unpredictable environments, and so their behavior must be flexible enough to deal with uncertainty and change. Plants also respond to stimuli.
Science in Personal and Social Perspectives – Content Standard F
As a result of activities in grades 5-8, all students should develop understanding of
- Populations, resources, and environments
- When an area becomes overpopulated, the environment will become degraded due to the increased use of resources.
- Causes of environmental degradation and resource depletion vary from region to region and from country to country.
- Natural hazards
- Human activities also can induce hazards through resource acquisition, urban growth, land-use decisions, and waste disposal. Such activities can accelerate many natural changes.
As a result of activities in grades 9-12, all students should develop understanding of
- Natural resources
- Humans use many natural systems as resources. Natural systems have the capacity to reuse waste, but that capacity is limited. Natural systems can change to an extent that exceeds the limits of organisms to adapt naturally or humans to adapt technologically.
- Environmental quality
- Human activities can enhance potential for hazards. Acquisition of resources, urban growth, and waste disposal can accelerate rates of natural change.
- Science and technology in local, national, and global challenges
- Humans have a major effect on other species. For example, the influence of humans on other organisms occurs through land use—which decreases space available to other species—and pollution—which changes the chemical composition of air, soil, and water.