Two updates in a month ?! So much going on and so much to
talk about. Introducing here a quick
update on the camera trial, eagle ringing, and more nest surveying, before delving
into the issue of population trends, persecution, and a visit to the museum.
Very briefly I will say that the nest camera trial has hit a
first hurdle – with the eagles proving their impressive strength and ability to
simply reject my intrusion. The camera was
ripped from its nest-site mount, lens pierced by a surgically precise talon,
and tossed to the ground. So a re-think
is in order. A sturdy encasement and an
extra meter or two distance from the nest?
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| a very suggestive pose - this pair has been mating frequently in the last week |
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| smashed lens |
I have made five attempts to ring another juvenile – and this
was the antithesis of the first which you may recall took but 20 minutes to
trap. This youngster is known to have
had an interest in the local monkeys, and the shop rooster – however nothing I
could do would encourage the wee eagle to a trap. There are at least four other juveniles in
other areas which I would also like to trap and ring. But I need a greater arsenal – and in between
the other main aims at this time I will be building a couple more trap designs
and getting crafty.
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| the untrappable juvenile |
Networking, public submissions, and additional surveying has
continued. Several more nest locations
have been filtering my way. There are
now a surprisingly large number of pairs - about twenty current and recently
active nest sites in the greater Durban area.
Three more were added while I spent the day with Richard Mckibbin.
A very popular and well known nest site is that of the
Kranzkloof gorge, and visiting this site for the first time last Tuesday
revealed the most fantastic nest site: a solid nest in a huge Mahogany tree
leaning out over the kloof gorge, and with a perfect line of sight from a clifftop
viewpoint only 60 meters above. The
female had enormous feet, something I noticed well as she stood on a mostly
plucked prey, probably duiker, on her nest lined with green twigs – a positive
sign that this pair will soon lay an egg this year.
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| Richard and I at the upper Kranzkloof nest |
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| particularly impressive feet! sorry for the grainy photo |
The population that I am studying seems to be thriving, all within
or surrounded by heavily populated areas.
Despite a few instances I have come across of local persecution – locally
the eagles are generally admired and protected.
It is important to recognize that this is an isolated bubble - circumstances
which separate this population from the majority of a wide African range from
west Africa across the Congo rainforest, and from Ethiopia down the eastern
edge of Africa to a southern limit at the Tsitsikamma mountains, South Africa. The bushmeat industry is a major contributor –
removing a great deal of biomass of their preferred prey of monkeys and
antelope. Hunters mimic eagle calls to hunt the monkeys, which respond by
approaching the sound to sight its nemesis.
The territorial eagle also has a similar response and may approach this
unseen intruder- only to succumb to a gun or arrow. More widespread ecological destruction can be
attributed to continued deforestation and mining of minerals in central Africa.
The IUCN Red List has published its 2012 revision, and the
plight of the Crowned Eagle has somewhat cautiously been recognized within its
ranks as a shift from Least Concern to Near Threatened – as a result of more
(but still rather limited) knowledge.
To continue with this morbid theme – I had the pleasure of
visiting the Curator of Ornithology at the Durban Museum, David Allan. David is still very much alive – animated even
– it is the ornithological collection I was referring too! The museum bird collection contains over
38,000 skins, of many brilliant and bright African species making it the third
largest collection on the continent.
There are several cabinets full of large raptors, including just ten
Crowned Eagle skins.
Sadly the most disappointing feature of the eagle skins that
I looked at was the prominent paucity of data on the collection tags. I was hoping to look at these skins and glean
several facets of information, particularly to identify the location and cause
of death.
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| one of the raptor cabinets |
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| Crowned Eagles |
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| [no data] |
While in the early days birders and collectors were out
there shooting masses of animals and harvesting clutches of eggs for private
and public collections, the times have changed.
The flow of specimens into museums has slowed considerably – despite it
being as useful as ever to have carcasses of ‘ natural’ deaths added to the
museum collections. I implore all who
have an interest in wildlife to not overlook these valuable specimens. Should you chance upon a freshly dead
specimen of an interesting species, pop it in the freezer and contact the
appropriate museum to arrange a cold courier to submit it. It must
have a data card with three essential items: The date, the most accurate
location possible (GPS position), and the collector’s name. Ideally any additional data should be added
like the cause of death if known.
One of the more poignant examples of the eagle skins at the
museum was the individual from the following news article – a female that used
to be paired with the male at the site of my current nest camera trials.
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| The Witness - January 1997 |
