Latest edition of African Birdlife
News from the FitzPatrick Institute
Solving the mystery surrounding the decline
Scientists have turned
to outer space to explain the mysterious disappearing act of one of Africa's
most famous birds.
attached to 18 Bearded Vultures have confirmed conservationists' worst
fears: humans are largely to blame for the rapid demise of the species.
throughout much of Southern Africa, the Bearded Vulture is now critically
endangered in the sub-continent, with a nearly 50 percent reduction in
nesting sites since the 1960s.
And the main reasons
for their decline are collisions with power lines and poisoning, two major
vulture hazards that killed half of the birds in the satellite tracking
Once widespread across
South Africa, the Bearded Vulture population is now restricted to the
Drakensberg mountains in Lesotho and South Africa. But even in these
isolated mountains the population continues to decline due to human
encroachment on nesting sites and feeding territory.
These are some of the
key findings contained in two new research projects published this month.
The studies paint the most detailed picture to date of the challenges facing
the Bearded Vulture, also known as the 'bone breaker' due to its habit of
dropping bones from a height to feed off the marrow inside.
The first paper,
published in the international ornithological journal The Condor  by
scientists from EKZN Wildlife and the Percy FitzPatrick Institute  at the
University of Cape Town, found that human-related factors were the common
denominator in differences between abandoned and occupied Bearded Vulture
territories. Lead author on the study Dr Sonja Krueger  said: “We
explored where the biggest difference lay between abandoned and occupied
territories and found that human related factors such as human settlement
density and powerlines were consistently different between these sites”.
Power line density and
human settlement density were more than twice as high within abandoned
vulture territories compared to occupied territories, the study found.
Results also suggested
that food abundance may influence the bird's overall distribution, and that
supplementary vulture feeding schemes may be beneficial.
By contrast climate
change was not found to be a major contributing factor in nest abandonment.
definitive, the results strongly suggest that we humans are our own worst
enemies when it comes to conserving one of Africa's iconic birds,” Krueger
The study recommended
a new approach to vulture conservation management: “Based on the identified
threats and mechanisms of abandonment, we recommend that conservation
management focus on actions that will limit increased human densities and
associated developments and influence the attitudes of people living within
the territories of (vulture) breeding pairs,” the study concluded. “We
recommend that mitigation of existing power lines, stricter scrutiny of
development proposals, and proactive engagement with developers to influence
the placement of structures is essential within the home range of a
The study's findings
are backed up by a second paper published in open access journal PLOS ONE
, which relied on data from satellite trackers attached to 18 Bearded
Vultures. The trackers not only showed the exact location of the tagged
birds every hour, they also provided critical information on movement
patterns and mortality. Tagging enabled dead birds to be quickly recovered
and their cause of death determined.
The study confirmed
that, in addition to power lines, poisoning was considered the main threat
to vultures across Africa and was contributing to the so-called “African
Vulture Crisis”-- a large decline of many vulture species across the
The tracking data also
provided new information about the birds' ranging behaviour. It revealed
that non-breeding birds traveled significantly further than breeding birds
and were therefore more vulnerable to human impact. Some young non-breeding
birds patroled an area the size of Denmark. The average adult bird had a
home range of about 286 square kilometres, but the range was much smaller
for breeding adults at just 95 square kilometres.
The tracking study,
conducted between 2007 and 2014, required some innovative fieldwork.
Researchers used meat lures to capture the birds at vulture feeding sites.
Each captured bird was then fitted with a 70g solar-powered tracker designed
to relay detailed information every hour between 5am and 8pm – including GPS
coordinates and flight speed.
Tracking results also
prompted the study authors to suggest several possible strategies to combat
the threats posed by human infrastructure such as wind farms and power
lines. These include: “ i) the mitigation of existing and proposed energy
structures to reduce collision risks; ii) the establishment and improved
management of supplementary feeding sites to reduce the risk of exposure to
human persecution and poisoning incidents; and iii) focussed outreach
programmes aimed at reducing poisoning incidents,” the study said.
Dr Arjun Amar  from
UCT said detailed knowledge about Bearded Vulture home ranges could be
hugely beneficial to vulture conservation: “We knew the species was likely
to have large home ranges, but our results show just how far these birds
travel – and therefore how exposed they are. The more they travel, the more
they risk colliding with power lines or falling prey to poisoning.” He
continued “what these two new studies suggest is that the impact of human
activity on the survival of the Bearded Vulture is even more serious than we
suspected. Plans for multiple wind farms in and around the highland regions
of Lesotho will likely place even more pressure on this vulnerable species
and may be the final death nail in this species coffin”.
For further information, please contact:
Arjun Amar –
Phone: +27 (0)21 650 3304
Sonja Krueger -
Sonja.Krueger@kznwildlife.com, phone +27 (0)0828774122
photo by Sonja Krueger
Full reference for this paper is: Krüger,
S., Simmons, R.E. & Amar, A. 2015. Anthropogenic
activities influence the abandonment of Bearded Vultures (Gypaetus barbatus)
territories in southern Africa. Condor. 117: 94-107.
Free access to full paper here:
Sonja Krueger is the
author of the paper. The research was undertaken as part of her PhD research
at the University of Cape Town.
full paper is freely available via open access. The full reference for the
paper is: Krüger S,Reid T, Amar A.(2014)
Range Use between Age Classes of Southern African Bearded Vultures
Gypaetus barbatus. PLoS ONE 9(12): e114920.doi:
Arjun Amar is a
Lecturer at the Percy FitzPatrick Institute, University of Cape Town and was
the lead supervisor of this research project.
Please report any sightings of ringed Swift Terns
Swift Terns are one of the few
locally-breeding seabirds whose numbers are increasing., To help understand
the main factors driving the positive trend of this species, a team of
researchers from the Percy FitzPatrick Institute and the Animal Demography
Unit at the University of Cape Town marked 500 Swift Tern chicks from Robben
Island in April 2013 and 2014 with metal and individually engraved colour
rings. In 2013, members of the public reported how these birds dispersed,
providing information on the fledging success, survival and dispersal of
juvenile Swift Terns, which were re-sighted from Namibia to the Eastern
Cape. Gathering dispersal records is a time consuming but important task
that relies on assistance from volunteers across southern Africa.
Rings in 2014 are orange and yellow
(with black text) and green and blue (with white text), and are engraved
with an “A” followed by a letter and a number (e.g. AU2). Rings from 2013
are yellow and white (with black text) and green and blue (with white text),
and bear a code of one letter and one number (e.g. U2). The majority of the
colour rings are top-down and all are on the right leg.
If you see any ringed birds please
record their location as accurately as possible (ideally GPS), the date and
time of sighting, ring colour, letters on the ring (if legible) and age
class (juvenile or immature). If a bird is found dead, please also record
the number of the metal ring. Send the
information to Davide Gaglio at
Thanks for your help!
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