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| A vulture that died from ingesting poison on a farm in Swartberg, KZN, South Africa. Photo from Ben Hoffman. |
Cape vultures (which
are listed as ‘Vulnerable’ under the IUCN Red List of Threatened and Endangered
species and are endemic to southern Africa) can consume a carcass in less than
an hour. During feeding time, vultures go into a frenzy and can fill their
crops in less than five minutes. Even their tongues aid in this eating
competition, with have grooves that point backwards to help move meat. After
this frenzy, these 9kg birds park off and socialize as their crops hang heavy.
In
Swartberg, KwaZulu-Natal, South Africa a vulture feeding frenzy occurred,
except most of those vultures did not live to digest the meal. Instead, a group
of about 50 vultures (48 dead and two rescued) staggered about a sheep carcass.
One by one their heads started to droop. Vultures that got the meaty bits of
the sheep’s stomach had blue crystals smeared on their feathers.
Instead
of the normal post-feeding behaviors (most of which we humans don’t
understand), the vultures started dropping dead. The amount of poison ingested
from the sheep carcass and the individual’s sensitivity to the toxin determined
how much time it had to live.
In
a matter of hours, the commercial farm was littered with vulture carcasses. All
is silent, as vultures typically do not consume the dead of their own kind. It
is not quiet back at the vulture breeding colony. Late July is peak hatching
time. Some adult vultures have been sitting on a single egg for almost 60 days.
Once the chick hatches, the parents have to franticly search for food to
nourish the growing chick and themselves. One parent will go search for food,
as the other guards the chick. Some of those partners will wait for days, staring
at the down-covered chick and the sky. There will come a point when that parent
will have to leave and find carcasses. Since their food source is ephemeral and
randomly located in the environment, it takes both parents to search for food
for the growing chick. With only one parent, the costs are too high for it to
feed itself and the growing chick, and the chick will die. A number of the dead
birds at Swartberg had brood patches (a patch on the abdomen that is used to
help incubate eggs).
When
I heard the news of the poisoning, it was an hour before I presented my project
on Cape vultures at the Zoological Society of Southern Africa. I did not know many details. I did not know
if any the vultures I ‘knew’ were involved. My project in collaboration with another from University
of Marburg (Germany), have tagged over 70 Cape vultures. With my 9
transmitters, I have followed their movements. This involved many hours in
front of a computer, following their flight patterns and admiring the great
distances they travel. I have also been lucky enough to observe tagged vultures
at the vulture colony. All I knew before my talk was that vultures have been
poisoned in Swartberg, an area in which all nine of the vultures I follow have
visited. I was very emotional.
I
have never named the vultures I follow, in an effort to resist the urge to personify
them. But I still knew them. I witnessed where these birds go when humans are
not watching. I can tell you the sex of a particular bird and where it resides
on the cliff. Some birds have traveled far from the colony, while others are
busy parents sitting on eggs. So no, they did not have names but they still lived.
These vultures were part of the greater web, performing a favor to the
ecosystem by devouring dead animals. Unfortunately, these vultures inhabit a
human-transformed landscape that threatens them at every thermal. This incident
is just one of the poisonings that we know of, and it is possible that there
are other incidences that will never surface. The poison was probably put out
to kill Black-backed Jackal, which attack and kill livestock. Along with the
dead vultures, a dead jackal, a dead Jackal Buzzard, and two Sacred Ibis were
found.
During
my 10 minute presentation I was nervous until I pointed out where the vulture
poisoning happened; located inside the foraging ranges of the vultures I
monitor. There was silence in the room. I took a deep breath and carried on.
Because we have to. We need to acknowledge the incident, let justice run its
course, and continue speaking not only on the behalf of the vultures but all components
of the web! Let’s keep this web strong!
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| Overview of the dead vultures. Photo form Ben Hoffman. |
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| Processing the dead vultures. Photo from Ben Hoffman. |
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