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Faulty
practices threaten success of California condor program, says
new report
25
Jul 2000
BLOOMINGTON,
Ind. - Current releases of captive California condors into the
wild probably will fail unless changes in the program are made
soon, according to a new study that will be reported in the
August issue of the journal Conservation Biology.
Captive rearing
techniques are producing excessively tame condors that pose
threats to humans, and the released birds are at constant risk
of death by lead poisoning from eating carcasses contaminated
with bullet fragments, which was a main cause of the extinction
of wild condors in the 1980s.
The article's
authors are Vicky Meretsky, assistant professor in the School
of Public and Environmental Affairs at Indiana University; associate
professor Steven Beissinger of the Department of Environmental
Science, Policy & Management at the University of California,
Berkeley; Noel Snyder of Wildlife Preservation Trust International;
David Clendenen of Wind Wolves Preserve; and James Wiley of
the Grambling Cooperative Wildlife Project at Grambling State
University.
"Many condors
are reared in captivity by humans using condor-shaped puppets,
and this has created birds that readily approach people, cars
and buildings," said Meretsky, lead author of the journal article.
In the past year, there have been repeated instances of condors
prying shingles off buildings, destroying camping equipment
and approaching people for food handouts, she said.
"Behavioral
problems have been common in released young condors that were
taken from their parents and reared by puppets in isolation,
but not in young condors that were raised by their parents,"
said Meretsky. "Unfortunately, despite this important difference,
program managers have continued to release puppet-reared birds
to the wild instead of limiting releases to parent-reared birds."
Lead poisoning
was a major factor responsible for the extinction of the wild
condor population in the mid-1980s, and it is killing condors
again because releases have been conducted without attempting
to solve the problem. In the last few months, five released
birds have died of lead poisoning and others are contaminated,
Meretsky said.
"Until sources
of lead contamination are effectively countered, releases of
captive condors cannot be expected to result in viable wild
populations," she said.
"To re-establish
any wild species, the main causes of its extinction must be
identified and eliminated before releases of captive animals
are attempted. This basic tenet is being neglected in the current
condor release program, even though alternative ammunitions
are now available," said Snyder, senior author of the recent
book, "The California Condor: A Saga of Natural History and
Conservation."
"The California
condor program is the flagship of endangered species conservation
programs," said UC Berkeley's Beissinger. "Large amounts of
money have been spent and many individuals have worked hard
to breed condors in captivity and to develop techniques for
reintroducing them to the wild. Success is definitely achievable,
but only if basic changes are made in the current condor release
program. If not, it may become a perpetual and very expensive
black hole."
California
condors once could be found along the Pacific coast from Canada
to Mexico. By the late 1970s, only about 30 birds remained.
A captive flock was started in 1982, and free-flying birds were
captured when it became clear that the wild population was beyond
rescue. The last wild condor was captured in 1987. Breeding
in captivity was successful, and releases of captive-born young
condors to the wild began in 1992. But the death rate of released
birds has been too great to sustain a wild population.
Part of the
problem is that birds raised using puppet condors have been
excessively tame, despite efforts to train these birds to avoid
humans and human structures. One group of eight birds wound
up in a resident's bedroom after tearing through a screen door
to enter the house. In Grand Canyon, a condor ripped through
the side of a camper's tent as he lay sleeping within.
Only one
release site, near Big Sur, Calif., has had a purely parent-reared
group of condors, and it has been essentially free of tameness
problems, Meretsky said. Unfortunately, these birds recently
expanded their range and joined one of the groups containing
puppet-reared birds, and now they are beginning to follow the
puppet-reared birds into developed areas.
"Mixing the
two stocks in the wild has resulted in the transfer of bad habits
from the puppet-reared to the parent-reared birds," Meretsky
said. "All misbehaving birds in the wild should be re-trapped
and returned to captivity, since they pose a risk of passing
on their bad behaviors to birds released in the future."
The study
strongly urges that future releases be limited to parent-reared
birds, especially ones that are raised free of all contact with
humans in field enclosures that do not resemble human structures.
Short-term
measures to reduce lead poisoning were suggested as far back
as the 1980s, when condor releases were first discussed. The
proposal was to use only one or two feeding locations to provide
condors with uncontaminated food until lead in their environment
was no longer a problem. But release programs have instead emphasized
more natural foraging patterns, using supplied food to tempt
the birds to fly more widely, and then reducing and even eliminating
the provision of safe food. First encouraged to feed on their
own and then forced to do so, condors are now dying of lead
poisoning.
"If lead
contamination persists in the environment and increased feeding
on natural carcasses continues, the mortality rate of released
condors will equal the disastrously high mortality that once
drove condors to the brink of extinction," Beissinger warned.
The most
promising solution is to require hunters in areas where wild
condors live to use a new non-toxic ammunition made from a composite
of tungsten, tin and bismuth (TTB), which has hunting characteristics
equal to lead ammunition, according to the study.
Government
agencies have made no move to require non-toxic ammunition in
areas where condors forage. However, the U.S. Army has begun
to substitute TTB for lead in ammunition, and commercial production
may begin soon.
"The technology
for a practical solution to the lead-poisoning problem is already
in hand. Government agencies need to be involved in encouraging
production of TTB ammunition and restricting ammunition in release
areas," Snyder said.
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Source:
Hal Kibbey, Office of Communications and Marketing, Indiana
University
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