Research Update #3 - mid June

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?

a very suggestive pose - this pair has been mating frequently in the last week

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. 

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.

Richard and I at the upper Kranzkloof nest

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.

one of the raptor cabinets

Crowned Eagles

[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. 

The Witness - January 1997