|Restoration of oiled African penguins Spheniscus demersus a decade after the Apollo Sea spill|
Wolfaardt, A.C.; Underhill, L.G.; Altwegg, R.; Visagie, J. (2008). Restoration of oiled African penguins Spheniscus demersus a decade after the Apollo Sea spill. Afr. J. Mar. Sci. 30(2): 421-436
In: African Journal of Marine Science. NISC/Taylor & Francis: Grahamstown. ISSN 0257-7615, more
|Authors|| || Top |
- Wolfaardt, A.C.
- Underhill, L.G.
- Altwegg, R.
- Visagie, J.
The bulk ore carrier Apollo Sea sank south-west of Dassen Island off western South Africa in June 1994, oiling approximately 10 000 African penguins Spheniscus demersus, most of which were collected from Dassen Island. A total of 4 076 de-oiled penguins was released with flipper bands. From 1994 to 2005, follow-up research using re-sighting and capturemark-recapture methods indicated that about 73% of the de-oiled penguins observed back at Dassen Island attempted to breed, and were thus successfully restored into the breeding population. For de-oiled breeders, the median interval between their first recorded sighting and first recorded breeding attempt was 11 months, indicating a short-term delay in restoration. At least 45% of the de-oiled breeders were still being re-sighted five years after their release, and a minimum of 4% survived into their ninth year. These results represent the most successful restoration estimates anywhere in the world. The proportion of de-oiled juvenile penguins re-sighted back at Dassen Island and recorded breeding was lower than that of birds in adult plumage. De-oiled non-breeders spent significantly more time along the shore and less time within breeding colonies than de-oiled breeders. The mean proportion of de-oiled breeders that abstained from breeding each year during the study period was greater than expected. There was a negative relationship between breeding and subsequent survival and breeding, suggesting a cost of reproduction for de-oiled birds.