Foraging plasticity of breeding Northern Rockhopper Penguins, Eudyptes moseleyi, in response to changing energy requirements
During the breeding season, seabirds must balance the changing demands of self- and off-spring provisioning with the constraints imposed by central-place foraging. Recently, it was shown that Northern Rockhopper Penguins at Tristan da Cunha in the South Atlantic Ocean switch diet from lower to higher trophic level prey throughout their breeding cycle. Here, we investigated if this switch is reflected in their foraging behaviour, using time-depth recorders to study the diving behaviour of 27 guard and 10 crèche birds during the breeding season 2010 at Tristan da Cunha and obtaining complementary stomach contents of 20 birds. While no significant effects of breeding stage were detected on any foraging trip or dive parameters, stage/prey had a significant effect on feeding dive parameters, with dive duration, bottom time, and maximum depth explaining the majority of the dissimilarity amongst categories. We verified the previously shown dietary shift from zooplankton and cephalopods during the guard stage to a higher-energy fish-based diet during the crèche stage, which was reflected in a change in dive behaviour from shorter, shallower to longer, deeper dives. This prey switching behaviour may reflect preferential selection to account for the increased physiological needs of chicks or simply mirror changes in local prey abundance. Nonetheless, we show that Northern Rockhopper Penguins demonstrate behavioural plasticity as a response to their changing energy requirements, which is a critical trait when living in a spatio-temporally heterogeneous environment. This ability is likely to be particularly important under extrinsic constraints such as long-term environmental change.
KeywordsNorthern rockhopper penguin Eudyptes moseleyi Tristan da Cunha Dietary shift Generalist Foraging plasticity
This work was carried out under the auspices of the Flagship Species Fund of the Department of Environment, Food and Rural Affairs (DEFRA) and Fauna & Flora International with funding from DEFRA, the Royal Society for the Protection of Birds (RSPB) and other donors under Project FSF-Defra- 10-48. The Department of Environmental Affairs through the South African National Antarctic Programme and the Tristan da Cunha conservation department provided logistical support. Thanks to T. Glass, J. Repetto, G. Swain, C. Repetto, M. Green and K. Green of the Tristan Conservation Department for their support in the field. M. Connan and anonymous reviewers provided helpful comments on an earlier version of this manuscript. This work is based upon research supported by the South African Research Chairs Initiative of the Department of Science and Technology and the National Research Foundation. Funding was provided by SARCHI (Grant Number 64801).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Full permission for all methods used in this study and access to the penguin colonies were granted by the Tristan da Cunha government. Animal ethics approval was given by Rhodes University Ethics Committee (ZOOL-17-2010). All applicable international and institutional guidelines for the use of animals were followed.
- Anderson M, Gorley RN, Clarke RK (2008) Permanova + for primer: guide to software and statistical methods. Plymouth Marine Laboratory, PlymouthGoogle Scholar
- Booth JM (2011) Trophic ecology of breeding northern rockhopper penguins, Eudyptes Moseleyi, at Tristan da Cunha, South Atlantic Ocean. Dissertation, Rhodes UniversityGoogle Scholar
- Box GE, Jenkins GM, Reinsel GC (1994) Time series analysis: forecasting and control, 3rd edn. Prentice Hall, New JerseyGoogle Scholar
- Breslow NE, Clayton DG (1993) Approximate inference in generalized linear mixed models. J Am Stat Assoc 88:9–25Google Scholar
- Clarke KR, Gorley RN (2006) Primer v6: user manual/tutorial. PRIMER-E Ltd, PlymouthGoogle Scholar
- Croxall JP, Davis LS (1999) Penguins: paradoxes and patterns. Mar Ornithol 27:1–12Google Scholar
- Cuthbert R (2013) Northern Rockhopper Penguin Eudyptes moseleyi. In: Gracia-Borboroglu P, Boersma PD (eds) Penguins: natural history and conservation. University of Washington Press, SeattleGoogle Scholar
- Cuthbert R, Cooper J, Burle MH, Glass CJ, Glass JP, Glass S, Glass T, Hilton GM, Sommer ES, Wanless RM, Ryan PG (2009) Population trends and conservation status of the Northern Rockhopper penguins Eudyptes moseleyi at Tristan da Cunha and Gough Island. Bird Conserv Int 19:109–120CrossRefGoogle Scholar
- Davis LS, Cuthbert RL (2001) Reproductive ecology of seabirds. In: Steel JH, Thorpe SA, Turekian KK (eds) Encyclopaedia of ocean sciences. Academic Press, LondonGoogle Scholar
- Dehnhard N, Ludynia K, Masello JF, Voigt CC, McGill RA, Quillfeldt P (2016) Plasticity in foraging behaviour and diet buffers effects of inter-annual environmental differences on chick growth and survival in southern rockhopper penguins Eudyptes chrysocome chrysocome. Polar Biol 39:1627–1641CrossRefGoogle Scholar
- Gaston AJ (2004) Seabirds: a natural history. Oxford University Press, OxfordGoogle Scholar
- Lack D (1968) Ecological adaptations for breeding in birds. Methuen, LondonGoogle Scholar
- Mauchline J (1980) The biology of mysids and euphausiids. Adv Mar Biol 18:1–681Google Scholar
- Orians GH, Pearson NE (1979) On the theory of central place foraging. In: Horn DJ, Mitchell RD, Stairs GR (eds) Analysis of ecological systems. Ohio State University Press, ColombusGoogle Scholar
- Pinheiro J, Bates D, DebRoy S, Sarkar D, Core Team R (2009) nlme: linear and nonlinear mixed effects models. R package version 3(1–131):1Google Scholar
- R Development Core Team. 2010. R: a language and environment for statistical computingGoogle Scholar
- Ratcliffe N, Crofts S, Brown R, Baylis AM, Adlard S, Horswill C, Venables H, Taylor P, Trathan PN, Staniland IJ (2014) Love thy neighbour or opposites attract? Patterns of spatial segregation and association among crested penguin populations during winter. J Biogeogr 41:1183–1192CrossRefPubMedPubMedCentralGoogle Scholar
- Xavier JC, Trathan PN, Ceia FR, Tarling GA, Adlard S, Fox D, Edwards EW, Vieira RP, Medeiros R, De Broyer C, Cherel Y (2017) Sexual and individual foraging segregation in Gentoo penguins Pygoscelis papua from the Southern Ocean during an abnormal winter. PLoS ONE 12:e0174850CrossRefPubMedPubMedCentralGoogle Scholar