Abstract: The Southern Ocean experiences major environmental variations, including changes in sea ice cover, which is known to influence the ecosystem structure and functioning. Sea ice affects the survival and the reproduction of seabirds by limiting the availability and the access to food resources. Understanding the relationship between sea ice and Adélie penguins’ breeding success requires the study of foraging strategies, which are the key of the energetic trade-off between survival and reproduction. This study, conducted over 9 years, permitted to face diving and breeding success data with sea ice parameters (concentration, extent, distance to open water and presence of polynyas). It has been shown that according to sea ice conditions, Adélie penguins can adopt different strategies. These strategies permit to maximize the profitability of foraging trips: optimisation of foraging effort (transit phase, maximum depth and post-dive duration) and choice of target prey. This suggests the existence of an optimal range of sea ice cover for this long-lived marine predator. However, we could not clearly identify the mechanisms involved in the relationship between sea ice and foraging efficiency. In order to better understand this relationship, it could be interesting to have more data concerning the studied individuals (sex, body condition, GPS data and prey ingested).

Abstract:

Bio-loggers are miniaturized autonomous devices that record and store quantitative data on animal behavior, localization, energetic and physiology. Used on free-ranging individuals, they allow monitoring naturally behaving (theoretically undisturbed) wild animals, not easily observable otherwise. However, according to the studied taxa, externally attached loggers may impede animal movement, or affect locomotion energetics, social and reproductive behaviours, and/or thermoregulation. They may also increase animal conspicuousness, predation or entanglement risk, and ultimately fitness in case of long-term deployment. Implanted devices may mitigate some of these effects, and can be seen as a good alternative for long-term eco-physiological studies. Using recent studies, I will outline how implanted loggers can improve our knowledge on the physiology of diving and call into question well-known physiological relationships. They can also refine proxies for prey consumption and enable for the first time to get data on immature king penguins during their first period of life at sea. Finally, within the Three R’s (reduction, refinement, replacement) framework, we discuss capture and handling evaluation, and the pros and cons of logger implantation in light of ethical considerations and data accuracy and reliability.        

 

Keywords: anesthesia, bio-logging, capture and handling, data bias, eco-physiology, free-ranging, implantation