Projects of the Animal Demography Unit

Colour-ringing of colonial waterbirds on the Cape peninsula

Site 3 - Robben Island

Doug Harebottle
Animal Demography Unit
Robben Island
Photo Les Underhill

The heronry on Robben Island is probably one of the largest off-shore breeding colonies for waterbirds in the southwestren Cape. During 2000 and 2001 the heronry supported close to 1300 nests consisting of 600 Cattle Egret, 600 Sacred Ibis, 100 Crowned Cormorant, 50 Little Egret and 4 Blackcrowned Night Heron pairs. The heronry was located amongst a large patch of Rooikrans (Acacia cyclops) trees on the southern end of the island. In 2002, the colony diminished to less than a third and abandoned the original site in favour of another Rooikrans-dominated area located just south of the harbour wall. Most of the Sacred Ibis abandoned the heronry and selected a grassland area on the western side of the island where they built their nests on the ground.

Three ringing sessions have taken place, two in 2002 and one in 2003. A summary of the birds colour-ringed to date is presented below.

Species 2002 2003 2004
Sacred Ibis 78 0 30
Cattle Egret 5 17 20
Crowned Cormorant 0 0 2
TOTAL 83 17 50
Acknowledgements

I would like to thank Mario Leshoro (Robben Island Museum) for permission to ring on Robben Island and for arranging the logistics in getting to the island. The following people assisted with the catching and ringing of birds: Sue Kuyper, Mario Leshoro, Jane Underhill, Kathy Calf, Bill Watson, Peter Nupen, Kim Smith, Sam Wishart, Audrey Koester, Marius Wheeler, Michael Brooks, David Swanepoel, Martyn Peck and Ruben Fijn.

Photo gallery

Photo Doug Harebottle
The Sacred Ibis breeding colony in 2002 was situated in an open patch of grassland on the western side of the island.

Photo Doug Harebottle
Over 200 adults were counted at or near the colony on 13 November 2002

Photo Doug Harebottle
To catch the juveniles, a holding pen or 'kraal' was set up and the birds were herded into this.

Photo Doug Harebottle
A juvenile Sacred Ibis bearing a SAFRING metal ring on the right leg and a green Darvic ring on the left leg. 13 November 2002.

Photo Doug Harebottle
One of the five Cattle Egret chicks that were colour-ringed in 2002 from the heronry near Murray Harbour.

Photo Doug Harebottle
One of the 17 Cattle Egret chicks that were colour-ringed in 2003 from the heronry near Murray Harbour. This bird bears an individual marking with a green ring above the metal on the left leg and a green ring on the right leg.

Photo Doug Harebottle
Two of the individually marked Cattle Egret chicks that were colour-ringed in 2003 from the heronry near Murray Harbour.

Any queries or questions can be directed to Doug Harebottle
email: doug@adu.uct.ac.za    Tel: (021) 650-2330   Fax: (021) 650-3434