| Dear
EarthTalk: What is the status of the hyena
in the wild? Though unloved by many, the hyena has always
struck me as one of God’s survivors.
-- Jim Reddoch, Portland, TX
| |
The
striped hyena and the brown hyena are both considered
„near threatened‰ by the International
Union for the Conservation of Nature, which maintains
a „Red List‰ of at-risk and extinct species
around the world. The spotted hyena, pictured here,
is doing well comparatively, but its population is
also declining, primarily due to habitat loss.
© Ikiwaner, courtesy Wikipedia |
Among
the most intelligent animals on Earth, three species of
hyenas still roam in wilder parts of Africa and Asia. Of
them, the striped hyena and the brown hyena are most at
risk. Both are considered “Near Threatened”
by the International Union for the Conservation of Nature
(IUCN), which maintains a “Red List” of at-risk
and extinct species around the world. The spotted hyena
is doing well enough to be considered of “Least Concern”
by IUCN, but its population is also declining, primarily
due to habitat loss.
In
general, hyenas are large, strong, flesh-eating animals
that hunt a wide range of prey but mostly feed on carrion
(the kills of other predators). They most closely resemble
dogs but are in fact more closely related to cats. When
full-grown, hyenas range from about 3 1/2 to 5 1/2 feet
long and weigh between 75 and 175 pounds. Considered as
smart as some primates, hyenas work in teams to hunt zebras
and wildebeests. They communicate through a series of yells
and growls, and their cries resemble human laughter.
The
striped hyena roams a very large, patchy range stretching
from northern Africa through the Middle East to India. Biologists
estimate that only 5,000 to 14,000 individuals exist today
in the wild. According to the IUCN, major reasons for the
animals’ decline include persecution (especially poisoning)
by humans, decreasing sources of carrion due to declines
in the populations of other large carnivores (wolves, cheetahs,
leopards, lions and tigers) and their prey, and changes
in livestock practices. “Humans are consistently indicated
as the major source of mortality…largely because the
[hyena] is loathed as a grave robber, and because of incidents
of damage to agriculture…and livestock,” reports
the IUCN. Also taking a toll is illegal hunting for striped
hyena skins and body parts for use in traditional medicine.
Meanwhile,
only 5,000 to 8,000 Brown hyenas today roam parts of sub-Saharan
Africa. The brown hyena is relatively safe in protected
areas, but clashes with humans elsewhere have taken their
toll. The IUCN reports that negative attitudes toward brown
hyenas prevail across South Africa and elsewhere, with many
ranchers and farmers shooting, poisoning, trapping and hunting
them with dogs. The UK-based Predator Conservation Trust
has established the Brown Hyena Research Project to help
form strategies to promote the long-term survival of the
species and its southern Africa habitat.
As
many as 47,000 spotted hyenas live in sub-Saharan Africa.
They suffer similar forms of persecution as other hyenas
but have fared better due to their ability to adapt to life
in proximity to humans.
The
IUCN’s Hyena Specialist Group focuses on developing
hyena conservation strategies worldwide through integrated
research and public education to change attitudes toward
these much maligned animals. Conservationists underscore
the importance of preserving hyenas because, if for no other
reason, we can learn much from them. For one, hyenas possess
unique immune systems that allow them to withstand diseases
that kill other animals. “Only if hyenas are available
to study will we be able to unravel the mysteries of their
immune responses,” reports IUCN.
CONTACTS:
International
Union for the Conservation of Nature; Predator
Conservation Trust; IUCN
Hyaena Specialist Group.
Dear
EarthTalk: I ride my bike to work along busy
urban streets. Should I be worried about inhaling pollutants
from vehicle emissions and other sources?
-- J. Kaufman, San Francisco, CA
| |
Aside
from the obvious physical safety considerations (especially
when talking on a cell phone!), biking on highly trafficked
roads exposes riders to considerable amounts of fine
particles, nitrogen dioxide and volatile organic compounds
spewing out of tailpipes.
© Getty Images |
The short answer
is, yes, probably. Cars, trucks and buses emit considerable
amounts of airborne pollution as they make their ways along
city streets and highways. The fine particles, nitrogen
dioxide and volatile organic compounds (VOCs) spewing out
of tailpipes have been linked to a wide range of human health
problems, from headaches to respiratory illness to cancer.
Though Australian researchers found that exposure to these
pollutants is actually higher while riding inside a vehicle
than while riding a bike, turning your handlebars in the
direction of back roads might still be a good idea, for
safety’s sake as well.
Western Washington
University Geophysicist Bernie Housen, concerned about the
air quality on his own bicycle commute along busy Bellingham
roads, recently launched a study of the magnetism in local
trees to gauge air quality along his route and elsewhere
in his region. The magnetism in a tree’s leaves is
created by tiny particles of iron oxides and other pollutants
that drift through the air, emanating primarily from eroding
vehicle brake pads and diesel exhaust. The particles are
small enough to pass through our nasal passages and get
lodged in our lungs. Housen and his colleagues found 10
times as much magnetism on urban roadside tree leaves as
on their rural counterparts that contend with little traffic.
Housen has also
altered his own bike route to campus to avoid the more polluted
thoroughfares. “One underlying concern is that if
you are riding your bike, you are being more physically
active; you are breathing deeper and breathing more air
in, and so if you are doing that in an area where there
is a concentrated elevation of this material it might not
be such a good thing,” he added.
Ironically, many
cities that offer dedicated bike lanes often lay them out
right next to busy bus lanes, unintentionally ensuring that
bicyclists breathe in as much diesel exhaust as possible.
“I ride along one of these high-traffic bus routes,”
Housen says, “and … there was between two and
five or six times more magnetic fine particulate matter
along the bus route than [on less-busy streets].”
Housen would like to expand his research so it could be
used by urban planners to better design bike and pedestrian
routes so as not to intermingle so much diesel transit and
pedestrian/bicycle traffic.
Of course, there
are other ways to track urban pollution levels. In the UK,
for instance, researchers from the government-funded Engineering
and Physical Sciences Research Council have created the
Urban Pollution Monitoring Project, which builds and distributes
GPS-enabled mobile pollution sensing systems that can be
carried by hand or placed on a bike rack. The group is using
data gleaned from the sensors to map where and when pollution
levels are at their highest around London and other UK cities,
and hopes to use its research to influence the way roads
and urban areas are planned in the future as well.
Those who want
or need to keep on riding through polluted areas should
consider wearing an anti-pollution respiratory mask, many
of which can filter out upwards of 95 percent of particulate
pollution before it enters the human lung. Some leading
manufacturers include Totobobo, G-Flow and Respro.
CONTACTS:
Urban
Pollution Monitoring Project; Totobobo;
G-Flow;
Respro. |
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