06.07.2017

Ringed Blue Cranes offer new insights


The Blue Cranes with the green-white coloured rings NHE and NHH were ringed as chicks, in the Etosha National Park in 2006 and 2007

In January of this year they were photographed as a breeding pair with a chick, by Alexandra Wilhelm in the National Park near Charitsaub

The Blue Crane, critically endangered in Namibia, occurs exclusively in the Etosha National Park and the Omadhiya lakes, a series of oshanas (seasonally flooded lakes) to the north of the park. To see this rare bird, tourists often visit areas near the Chudop waterhole in the Namutoni area, Salvadora in the Halali area, and recently at Nebrownii, east of Okaukuejo in Namibia’s most famous park.

In January 2017, Alexandra Wilhelm from Germany photographed a pair of Blue Cranes with a chick, near Charitsaub in the Etosha National Park. The foreign visitor was amazed when she realized that both parents were ringed. Inquiries made with Holger Kolberg, scientist at the Ministry of Environment and Tourism, revealed that one of these birds (colour ring NHE) was ringed on 26 April 2006 by Kolberg himself, together with its sibling (ring NHF). The other bird with the engraved colour ring NHH, was ringed as a chick, near Salvadora, by nature conservation officer, Wilferd Versfeld on 12 March 2007. The two cranes, who were marked over ten years ago in the Etosha National Park, are now a breeding pair in the park, raising their own chick.

In the 1970s, more than 100 Blue Cranes occurred in the Etosha National Park and neighbouring Omadhiya Lake area (1976:138). In December 1994, there were only 60 of these rare birds left and in recent years the number has varied between 30-35 individuals (adults and chicks). It is not known what caused the decline and where the birds move in certain months.

To gain information, chicks were marked and some adults were fitted with radio transmitters. Several of these ringed birds have been sighted in the National Park. Unfortunately, the transmitters, especially the very expensive Satellite transmitters, only worked for a few weeks and then all signals were lost. Therefore, the researchers have not yet been able to establish where the small, isolated group of cranes disappear to when they leave the Etosha-Omadhiya area. A theory that the birds move to Angola lacks confirmation. It is, however, certain that the small population in Namibia has no contact with the 25,000 Blue Cranes in South Africa. The birds, endemic in southern Africa, are threatened by extinction, as numbers are continuously decreasing.

Photographs of ringed birds along with their location and date of sighting are very valuable to researchers and help them to slowly but surely understand the behaviour of the birds.

 

Dirk Heinrich


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