Recent trends in diet composition and productivity of gentoo, magellanic and rockhopper penguins in the Falkland Islands

Abstract

1. Over the past 14 years, data on diet composition and productivity of gentoo penguins (Pygoscelis papua), magellanic penguins (Spheniscus magellanicus) and rockhopper penguins (Eudyptes c.chrysocome) breeding in the Falkland Islands have been compiled as part of the Falkland Island Seabird Monitoring Programme. This paper comprises a summary of the data obtained so far, in particular concentrating on inter-annual and interspecific variation in productivity and general diet composition. 2. Productivity of all three penguin species has improved or remained stable over the last few years. The highest average productivity of 0.95 (ranging from 0.41 to 1.51) chicks fledged per breeding pair was observed in gentoo penguins. Productivity of rockhopper penguins during the same period was on average 0.80 (ranging from 0.63 to 0.91), and the lowest productivity of 0.78 (ranging from 0.19 to 1.49) was observed in magellanic penguins. 3. During the breeding season, all three penguin species preyed opportunistically on a mixture of fish, squid and crustaceans, with the general diet composition showing a high degree of spatial and temporal variation. The diet of all three penguin species overlapped with the commercial fishery for Patagonian squid Loligo gahi. There may also be some competition for Patagonian toothfish (Dissostichus eleginoides), hake (Merluccius sp.) and southern blue whiting (Micromesistius australis), because the juveniles of these commercially exploited species were regularly found in the penguin diet. Copyright © 2002 John Wiley & Sons, Ltd.