Conservation Corner No. 4 – November 2023 by Jane Doherty.

Les Underhill and his students have been monitoring African Oystercatchers on Robben Island for just over 20 years (the current project co-ordinator is Karis Daniels). Long-term studies such as these allow scientists to examine the impact of various natural and man-made threats on a species.
The view from the ferry of Robben Island, with Table Mountain in the background

Apart from its poignant political history, Robben Island is interesting because its natural ecosystem has been transformed by human intervention – clearing natural vegetation, building physical infrastructure and introducing alien species of plants and animals. The natural impact of weather is also dramatic on a low-lying island. Occasionally violent storms, such as those experienced recently, scrape vegetation and nests off the shoreline.
Around November, the Oystercatchers start creating their nests as scrapes (small depressions in the ground) above the spring tide mark on the bank

African Oystercatchers are currently doing well on the island, however. This is partly due to conservation efforts but also to the invasion of the rocky shoreline by the alien Mediterranean Mussel, which supplies a steady source of food. Les Underhill and three assistants counted 395 adult birds on 10 November. It appears that the population may be stabilizing around this number, after a low of 150 at the start of the project.

The Oystercatchers are just starting to breed, and the project is beginning to identify and mark nests, as well as weigh and measure the first eggs to determine the lay date. Handling the eggs does not affect the embryos so Robben Island is looking forward to its next crop of hatchlings.

More information on the findings of the Robben Island Oystercatcher Project is available from an Open Access paper,
in the journal Wader Study at DOI: 10.18194/ws.00245.

Photographs by Jane Doherty.

Report by Jane Doherty.



Leave a Reply

You must be logged in to post a comment.