African penguin dispersal

Juvenile birds, on the other hand, are theoretically free to disperse to areas where resources are more plentiful and may move considerable distances from the colony at which they hatched. Although African penguins are faithful to their colonies once they start breeding, in the last three decades they have initiated three new mainland breeding colonies and re-colonised one former breeding site. Most of the birds that bred at these new colonies in their early years were first time breeders that moved from other colonies. This emigration is thought to be a response to changes in the local or regional availability of prey, but seabird breeding colonies are restricted to sites free from disturbance and protected from land-based predators.

Based on this knowledge, as well as the success of interventions to hand-rear chicks orphaned following oil spills, it has been proposed to initiate and protect a new mainland breeding colony closer to the breeding stocks of the sardine and anchovy. The African penguin Chick Bolstering Project (CBP) was initiated to investigate whether chicks abandoned by their parents and reared to fledging age by SANCCOB could be used to bolster declining colonies and establish a new colony on the south coast. For such an endeavour to be successful, it is crucial that we understand whether these chicks survive and recruit into breeding populations as well as wild chicks. Some insight into the mechanisms that govern whether fledglings return to the colony in which they hatched or disperse to other sites is also crucial. Unfortunately, the period of the African penguin life cycle from fledging until they return to breed at around three to four years old is poorly studied.

We have used a combination of data from chicks marked with flipper bands (more recently micro-chips) and data obtained from tracking juveniles at sea (see image) to help understand at what age penguins develop the knowledge of where they will breed and how this decision may relate to the conditions they experience in the nest as well as at sea post fledging. To date, we have identify some key foraging areas used by juvenile penguins on the west coasts of South Africa and Namibia and contributed to population modelling. More information on the tracking component of this study can be found here. Updates on this project were posted in Environment magazine (see Publications) and some of the results were recently published in Current Biology.

The Chick Bolstering Project is a collaboration between SANCCOB, the Bristol Zoological Society, the Animal Demography Unit, the (then) Department of Environmental Affairs, CapeNature, Robben Island Museum and the International Fund for Animal Welfare (IFAW).