African Penguins on Robben Island
This research forms part of an interdisciplinary, multi-organisation initiative to build a better understanding of the changing ecology of the Benguela upwelling ecosystem and develop an ecosystem approaches to fisheries in South Africa.
The African penguin is endemic to southern Africa and the present population is estimated to be about 2% of what it was 80 years ago as a result of prolonged human activity in the region. In South Africa, estimates of the number of African penguins breeding decreased from 56 000 pairs in 2001 to 17 000 pairs in 2019. On Robben Island, the population re-established after more than 100 years of absence in 1983, when 9 pairs were found nesting. The breeding population then grew to over 8 000 pairs in the mid-2000s before dropping dramatically to around 1 000 pairs today.
The species is currently listed as Endangered on the IUCN Red List, meaning it is considered to be facing a very high risk of extinction in the wild.
Since 2001 (the year following the Treasure oil spill), a sample of around 200 nests has been followed intensively as part of an Earthwatch project, on which I am Lead Scientist. Nests are checked approximately every 10 days and the contents and presence of adults recorded. The project also monitors individually marked birds to obtain data on survival rates, longevity and lifetime reproductive success; conducts counts of penguins moulting along the shoreline (data which forms the basis of assessments for the IUCN Red List) and assists with the annual census of breeding pairs.
From the beginning of the 2008 breeding season, the monitoring being carried out was part of a multi-partner project investigating the efficacy of closing areas around seabird colonies to fishing as a conservation tool. As penguins are thought to be restricted to foraging within 20 km of their breeding colony while feeding chicks, it is hoped that such closures will benefit breeding birds by increasing the prey available to them during the crucial chick rearing stage (see here for more information).
During the winters of 2008 and 2009 and from 2014 to 2016, an area around Dassen Island (30 km north of Robben Island) was closed to fishing, while a similar area around Robben Island was open. From 2011 to 2013 and from 2017 to 2019, the situation was reversed.
By comparing the penguin populations at these two colonies, and monitoring any differences in the birds’ ability to supply food to their chicks in the closed and open areas, we can obtain crucial information to guide future legislation on fisheries management, such as spatially enforced fishing quotas or the development of Marine Protected Areas.
In each year a sample of chicks are weighed and have their head and/or flippers measured. These data are used to generate an index of body condition and to compare growth rates over time between closed and open colonies to assess if and how fishing impacts on the productivity of African penguins.
In addition, to understand how changing fish stocks affect the penguins, it is necessary to know where they go to find the fish, how long it takes them to find the fish and then how much time it takes them to catch enough prey to feed both themselves and their chicks. Penguins from Robben Island are selected to be fitted with small, lightweight GPS and time-depth data-loggers. These are attached to penguins using tape to temporarily affix the loggers to the bird’s feathers. Once the logger is fitted the birds will be tracked as they perform one foraging trip (see the fourth picture). When the bird returns, the data are downloaded from the loggers and the data are analysed using GIS software to find out where the penguin went (see second picture). Between 2011 and 2013 this work was the focus of my PhD student Kate Campbell. You can learn more about her tracking work on her research blog and in her recent publication.
The data obtained from Robben Island are used in reports to the South African government and other working bodies responsible for overseeing pelagic fisheries in South Africa. In addition, the results of the breeding success studies and survival estimates have been summarised in six publications since 2012.
If you would like to help our efforts to monitor the penguins on Robben Island, please have a look at our Earthwatch project page. Or consider donating to the Bristol Zoological Society's African penguin conservation project.