Behavioural flexibility during year-round foraging in macaroni penguins

Abstract

Penguins are major consumers in the marine environment. However, like many top predators, very little information exists on their foraging behaviour outside the breeding season. We investigated the foraging behaviour of the macaroni penguin Eudyptes chrysolophus continuously for 2 consecutive years, from the end of December 2001. This allowed us to investigate whether foraging behaviour varied between sexes, years or phases of the annual cycle. Male penguins tended to dive deeper and longer than female penguins, but at a lower frequency, probably as a result of their larger body size. There was little variation in foraging behaviour between the 2 years studied, although neither year included a notable period of low Antarctic krill abundance. Diving behaviour varied substantially within years and general linear models were used to investigate this variability. In summary, all penguins tended to dive deeper, longer and more efficiently during their winter migration than during the summer breeding season. The penguins dived predominantly during daylight hours at all times of the year, but appeared to be more constrained by daylight during the short winter days. Several diving variables including dive duration, dive rate and amount of time spent diving were significantly related to day length and these associations were stronger during winter than summer. The macaroni penguin shows flexibility in its foraging behaviour as it adapts to differing constraints and challenges during its annual cycle. KEY WORDS: Behavioural plasticity · Penguin · Southern Ocean · Diving behaviour · Eudyptes chrysolophus Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 296: [183][184][185][186][187][188][189][190][191][192][193][194][195][196] 2005 hence food demands are likely to be high (Green et al. 2002), but there is currently no information about the location, foraging habits or diet of macaroni penguins during this period.This paucity of information on year-round behaviour is not restricted to macaroni penguins. With the exception of some information on location (Weimerskirch & Wilson 2000, no other seabirds, or indeed any other marine predators, have had their foraging behaviour studied continuously throughout their annual (or biannual) cycle. However, several species have been studied at different times of year, or at the same time in years of differing environmental conditions, including king penguins Aptenodytes patagonicus (Charrassin & Bost 2001) and Antarctic fur seals Arctocephalus gazella . These studies frequently identified differences in foraging patterns at different times of the year. The changes are often related to differences in foraging location and therefore the underlying oceanography/topography (Charrassin & Bost 2001 and/or prey species (Kato et al. 2003). This flexibility in behaviour illustrates the importance of studying animals at all stages of their life history, in order to understand how they interact with their environment and how they might re...

Inter-population segregation in the wintering areas of macaroni penguins

“…1, 3 & 4) suggest that macaroni penguins target predictable foraging areas in winter, thus concentrating their foraging effort within a restricted part of their potential range and suitable habitats (Wilson 1995, Bost et al 1997. It is also worth noting that none of the tracked birds came ashore during the winter, thus remaining at sea for over ~6 mo, confirming previous studies based on land-based observations (Warham 1975) and winter diving data (Green et al 2005).…”

“…1), would reveal whether those birds mix with the birds reported here. In the same way, the winter food and feeding ecology of the huge population of macaroni penguins that breed in South Georgia (southern Atlantic Ocean) remain essentially unknown (but see Green et al 2005), although these birds also seem to be distributed in the PFZ during winter (British Antarctic Survey unpubl. data).…”

“…Ballard et al 2010), thus suggesting a similar spatial niche for males and females. However, more subtle differences between sexes may appear when the vertical dimension of their niche is investigated (Green et al 2005), indicating that sexual segregation may occur through a differential depth use by macaroni penguins.…”

Corticosterone Predicts Foraging Behavior and Parental Care in Macaroni Penguins

“…This has been previously shown as a reliable proxy for prey capture during foraging events and correlates positively with bill openings and closings (Ropert-Coudert et al 2001;Simeone and Wilson 2003;Takahashi et al 2004;Bost et al 2007). Because of surface noise, we used a conservative approach and analyzed dives 110 m in depth, which is the suggested depth threshold for foraging dives of macaroni penguins at Bird Island, South Georgia (Green et al 2005).…”

Short-term movements and diving behaviour of satellite-tracked blue sharks Prionace glauca in the northeastern Atlantic Ocean

“…Several of these tracking studies have identified variability in the behaviour of marine fish, turtles, birds and mammals, indicating that this may be a common feature (Folkow et al 2004, Green et al 2005). For example, temporal shifts in behaviour have frequently been recognised at dif-ferent seasonal and/or diel scales.…”