In this video segment excerpted from the “The Road North” episode of the PBS series NATURE, guide and host Chris Morgan travels to Anchorage, Alaska to observe the increasingly close and sometimes uneasy co-existence of humans and black bears. While not particularly aggressive, black bears have proven all too adaptable to urban environments and are increasingly common within the city limits, testing the limits of “how much wild… people in Anchorage [are] willing to tolerate.”
- Why are humans more likely to encounter black bears than brown bears in the streets and backyards of Anchorage?
- What measures could be taken to reduce the black bear presence in Anchorage? Could these measures be considered our own “adaptations” to black bears, just as they’ve adapted to us?
- How large is the “home range” of a mother black bear and her cubs?
- What adaptations to urban life might future generations of black bears exhibit?
With close to 300,000 residents, Anchorage is Alaska’s largest city, but it is still a relatively small enclave of human settlement in the vast Alaskan wilderness that surrounds it. While this untamed natural environment is perhaps Anchorage’s biggest attraction, it also presents the city with some unique challenges–not least of which is residents’ sometimes uneasy co-existence with bears.
While the approximately 60 brown “grizzly” bears local to Anchorage tend to avoid humans, preferring to remain in the woods and salmon-filled streams on the outskirts of town, the 200-300 strong population of smaller black bears has proven much more adaptable to urban environments. The black bears’ foraging and scavenging skills–originally developed to better locate carcasses and other sustenance in often harsh sub-arctic environments–are well suited to locating easy meals in unsecured garbage cans dispersed throughout Anchorage’s residential neighborhoods.
Anchorage residents are divided about how best to deal with the black bears. Their presence is regarded by many as a charming–if occasionally inconvenient–element of their uniquely natural environment. The bears aren’t hunting for people, they maintain, but rather left-behind food scraps, and they are fairly easily scattered back into the woods. Those with this more permissive perspective are more likely to accept their own relative newcomer status to Alaska and adapt themselves to the wildlife–including black bears–more native than themselves.
On the other side of the debate are those who argue for stricter controls on the bear population by allowing freer hunting of the animals. They point to a rising incidence of human-bear encounters as the human population grows and pushes out further into the wilderness. While violent encounters have been rare–mostly involving larger and rarer grizzlies–black bears have become very common sights, and many residents are concerned about how future generations of these readily adaptive black bears will interact with humans. Unlike the more solitary and evasive grizzlies, black bears have lived unhunted among Anchorage’s neighborhoods for years, growing accustomed to humans, and perhaps no longer having what many would consider to be a healthy respect for us.
What most people in Anchorage can agree on is that greater public awareness of bear behavior is necessary. The Alaska Department of Fish and Game has conducted a door-to-door outreach campaign to heighten awareness of what attracts bears and how to avoid provoking dangerous reactions from them, and laws have recently been passed prohibiting trash from being put out except on pickup day.
Life Science, Content Standard C
As a result of their activities in grades 9-12, all students should develop understanding of
- Biological evolution
- Species evolve over time. Evolution is the consequence of the interactions of (1) the potential for a species to increase its numbers, (2) the genetic variability of offspring due to mutation and recombination of genes, (3) a finite supply of the resources required for life, and (4) the ensuring selection by the environment of those offspring better able to survive and leave offspring.
- Interdependence of organisms
- Organisms both cooperate and compete in ecosystems. The interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years.
- 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.
- Like other aspects of an organism’s biology, behaviors have evolved through natural selection. Behaviors often have an adaptive logic when viewed in terms of evolutionary principles.