VHF-TELEMETRY OF HUMBOLDT
PENGUIN FORAGING ACTIVITIES
IN NORTHERN CHILE

Boris M. Culik and Guillermo Luna Jorquera
Institut fuer Meereskunde
Duesternbrooker Weg 20, D-24105 Kiel
Email: bculik@ifm.uni-kiel.de

INTRODUCTION VHF-telemetry was used on Humboldt penguins (Spheniscus humboldti) breeding at Pan de Azucar Island (26°S, 70°W), Northern Chile, in order to determine a) the area utilization of the birds when foraging at sea, b) the dive duration during travelling and feeding dives, c) travelling speed of the birds, and d) whether birds return to specific areas on subsequent days.

METHODS Humboldt penguins were equipped in November 1994 (n=5 birds) and in November 1995 (n=8 birds) with streamlined Telonics MOD 225 transmitters. The birds were anaesthetised at the nest site to minimize stress while being handled, and the transmitters attached to the feathers on the back, below the line of maximal girth. Directional receiving antennas (null peak) were placed at approx. 3km and 4km to the North-East and South- East of the breeding island on the main land, at 230m and 350m elevation, respectively. Antennas were manned for 8h per day.

RESULTS We obtained 2710 positions (1995) of the birds at sea, 95% of which were within a radius of 22 km around the breeding island. The data allow a detailed analysis of the area utilization of breeding Humboldt penguins from Pan de Azucar Island, as well

as the determination of travelling speed, dive duration, time spent in certain areas and day to day variations in feeding area utilisation.

DISCUSSION In a previous study, we utilised satellite transmitters to determine where Humboldt penguins from Pan de Azucar Island forage (Culik and Luna, Mar Biol, 1997). The present study served the purpose to increase sample size and spatial resolution. The data will also be discussed with respect to the results of yet another study employing dive recorders (activity below the water surface) on some of the VHF-equipped birds (Luna and Culik, Mar Ornit, 1997).