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Our World at Risk
Karoo Birds on a Line
The open, arid Karoo is home to six bustard species and
South Africa’s national bird, the Blue Crane (
Anthropoides
paradiseus
). Unfortunately, bustards andcranes are relatively
cumbersome in flight, and are unable to react rapidly
when they encounter unexpected aerial obstructions.
Historically, they have had the freedom of open skies, but
the proliferation of power lines and the future installation of
wind turbines pose a real threat to these birds. FitzPatrick
Institute students have been investigating the implications
of power-line collisions in the Karoo, particularly for the
endemic Ludwig’s Bustards (
Neotis ludwigii
).
Avian Malaria in the
Western Cape
We are familiar with malaria as a human disease that is
almost unavoidable in sub-Saharan Africa, and indeed
across several other regions of the globe. But human
malaria has many counterparts in the animal kingdom,
one of which is avian malaria. Unlike the human form,
which is caused by parasites of the genus
Plasmodium
,
avian malaria is caused by three genera:
Plasmodium
,
Haemoproteus
and
Leucocytozoon
.
Research Projects
Jess Shaw recently graduated with a PhD for her
research into the impact of power-line collisions on
large Karoo birds. By regularly surveying hundreds of
kilometres of high-voltage power lines in her Mazda
Wildlife Fund vehicle, she was able to count bird
carcases, and noted that many were not found because
they were overlooked, or were removed by scavengers.
Shaw also regularly looked for dead birds along low-
voltage power lines, finding that these are nearly as
lethal for Ludwig’s Bustards as the larger power lines.
Considering that the low-voltage line network is nearly
four times the size of the high-voltage grid, this is of
great concern. She estimates that power lines kill tens
of thousands of Ludwig’s Bustards annually.
But, surprisingly, she also found little population
decrease compared with 20 years ago, suggesting
that Ludwig’s Bustards may be more productive
breeders than previously thought.
Marking power lines with devices to make them more
visible is the standard international mitigation for
collisions, but evidence that it works for the Ludwig’s
Bustards and Blue Cranes is lacking. In the autumn of
2011, together with staff from the Endangered Wildlife
Trust and Eskom, the researchers put up a large-scale
line-marking experiment over 70 km of high-voltage
power lines from a helicopter in the eastern Karoo.
This will test whether the marking devices reduce
bird-collision mortality, particularly for Ludwig’s
Bustards and Blue Cranes.
Avian malaria is capable of devastating impacts on
its hosts, with the best-known case study of what can
occur when an alien infectious disease is introduced
into a region having taken place in Hawaii. Following
the introduction of a mosquito vector, several forms of
avian malaria contributed to the extinction of several
honeycreepers, and had serious consequences for
many other endemic Hawaiian birds. There is evidence
that rising temperatures in Africa and elsewhere may
facilitate the expansion of the range for avian malaria.
The Western Cape is blessed that it remains free of
human malaria. However, the same cannot be said
for avian malaria, which causes isolated fatalities in
chickens, penguins and ostriches, with resultant socio-
economic impacts. Many wild African birds can act as
natural carriers of the disease without succumbing to
its effects. In spite of this, not much is known about
the ecology of avian malaria, especially in an African
context. Former PhD student Sharon Okanga and
her colleagues investigated the incidence of avian
malaria in Western Cape passerine birds. She assessed
which bird species were more susceptible to infection
and looked for signs of preference in the malaria
parasites. Blood samples were taken from 1 000 birds
at 26 wetlands in the Western Cape. Avian malaria
prevalence varies among bird species, with weavers,
wagtails and canaries having higher infection rates
than other bird families. Research continues into
various areas of avian malaria.
The proliferation of power lines and
the future installation of wind turbines
pose a real threat to these birds.
Avian malaria prevalence varies among
bird species, with weavers, wagtails
and canaries having higher infection
rates than other bird families.