Plasticity in the foraging behavior of male Southern Rockhopper Penguins (Eudyptes chrysocome) during incubation in the Falkland/Malvinas Islands

Abstract

Environmental changes often affect the persistence of species or populations at different spatial and temporal scales. Thus, species must either adapt to these changes or experience negative impacts at the individual or population levels. Southern Rockhopper Penguins Eudyptes chrysocome are distributed throughout the Southern Ocean and have experienced substantial declines in the past which were linked to various anthropogenic and environmental factors. The aim of this study was to investigate the foraging behavior of male Southern Rockhopper Penguins at Berkeley Sound, East Falkland, Falkland/ Malvinas Islands, during incubation, a period at-sea which is crucial for replenishing body condition between two extended fasting periods ashore. Thus, birds are forced to forage efficiently during that time to balance their energy demands. We linked their at-sea distribution and foraging behavior to satellite-derived sea surface temperatures and temperature-depth profiles which were recorded by devices attached to the birds. While Southern Rockhopper Penguins usually travel several hundreds of km out into the open sea on multiple-day trips during incubation, we found in our study that most birds foraged close inshore, less than 9 km away from their colony, and regularly returned to their breeding site. We propose that this behavior occurred in response to the close proximity of the 8 °C SST isotherm and the vertical stratification of the waters therein. Also, while usually feeding pelagically in open waters, there are strong indications that Southern Rockhopper Penguins performed benthic or, at least, near-bottom dives to catch their prey during these short trips. The consequences of this behavioral plasticity in response to variations in sea temperatures and inferred prey availability are discussed, especially with regard to predicted global climate change.

Potential for redistribution of post‐moult habitat for Eudyptes penguins in the Southern Ocean under future climate conditions

“…The suite of CMIP5 models chosen here all showed strong agreement towards a southward redistribution of penguin habitat. As sea surface temperature may indeed be the most important indicator of penguin foraging, as shown in our study as well (Cristofari et al, 2018;Le Bohec et al, 2008;Morrison et al, 2015;Pütz et al, 2018;Rey et al, 2007), the implications for poleward warming of the frontal zones may be significant enough to have negative effects on widely dispersive penguins. Sea surface temperature affects the locations of foraging for penguins and even short-term poleward shifts of isotherms have resulted in decreases in survival rates and breeding success for penguins (associated with increased energy expenditure when foraging for food;…”

Happy Feet in a Hostile World? The Future of Penguins Depends on Proactive Management of Current and Expected Threats

“…Changes in foraging behavior in terms of either horizontal or vertical distribution, or of prey species, could be one means of potential buffering. Southern rockhopper penguins are one of the few species that have displayed substantial male behavioral change in response to environmental change with the potential to increase reproductive outcomes (Pütz et al, 2018). Similarly, snares and fiordland penguins may be less susceptible to warming as they are more flexible in their foraging behavior when feeding at either the sub-Antarctic and/or sub-Tropical Fronts (Mattern et al, 2009).…”

Important marine areas for the conservation of northern rockhopper penguins within the Tristan da Cunha Exclusive Economic Zone

“…The birds we tracked from Gough travelled south towards the Subantarctic Front, but this frontal system is beyond the range of incubation trips from Nightingale, which were instead dispersed in a longitudinal direction staying to the north of the STF. Other Eudyptes species similarly show plasticity in their use of fronts and water masses during incubation (Hull et al 1997, Barlow & Croxall 2002a, Ludynia et al 2013, Pütz et al 2018. This spatial and temporal segregation results in birds from Gough and the northern islands foraging in different water masses throughout the breeding season and potentially experiencing different threats (see Section 4.2).…”