Breeding Jackass Penguins as pelagic predators

The foraging of breeding Jackass Penguins Spheniscus demersus was studied in and around southwestern Cape Province, Saldanha Bay (33⁰ S, 18⁰ E), South Africa. Penguins are difficult to observe at sea. Hence, I devised a number of new techniques for studying the foraging behaviour of Jackass Penguins at sea. I built electronic and autoradiographic remote-sensing devices to measure swimming speed, distance travelled and time spent at each depth by foraging Jackass Penguins. Penguin swimming speed was reduced in proportion to the cross-sectional area of the devices, and results derived from birds wearing the devices had to be interpreted accordingly. Penguins do not regurgitate their stomach contents when handled, so I constructed a wet-offloading stomach pump which extracted 100% of the stomach contents. Using this pump, I determined that the rate of digestion of fish and squid by Jackass Penguins differed. Care is needed in diet interpretations where both fish and squid are major food items.

Grantor dc:publisher.institution

Percy FitzPatrick Institute of African Ornithology

Year dc:date.issued

1986

Author dc:creator

• Wilson, Rory Paul

Advisor dc:contributor.advisor

• Siegfried, Roy

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/17653

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/17653