HUMBOLDT PENGUINS MONITORED VIA VHF TELEMETRY

VHF telemetry was used in November and December 1995 on 8 Humboldt pen guins Spheniscus humboldti breeding at Pan de Azucar Island (26 degree s S, 70 degrees W), Northern Chile, to determine at-sea behaviour of t he birds. We obtained 2710 locations, 90% of which were within a radiu s of 20 km around the island. Mean travelling speed of the birds was 0 .92 m s(-1) and speed distribution showed peaks at 1.6 and 3 m s(-1). Penguins travelling between foraging areas remained submerged for an a verage of 8.4 s between surfacings, whereas foraging dives lasted on a verage 61 s. The analysis of 79 complete foraging trips showed that tr acks deviated from a straight course, and range (maximum distance from island) was only 0.37 times total horizontal distance swum. Birds did not forage synchronously or in the same foraging areas. However, fora ging ranges were correlated between birds, indicating similar search s trategies during periods of low food availability. The results obtaine d here via VHF telemetry agreed well with those of previous studies em ploying satellite transmitters and data loggers.