Blood chemistry values in nestlings of Rockhopper Penguins (Eudyptes chrysocome): the effect of sex and body condition
Hematological studies concerned with the determination of normal values of blood parameters in animals have been increasing. However, studies on normal concentration of blood constituents of free-living birds still are not very common, and less than 5% of the species of birds have been analyzed, mostly in captivity. Avian hematology has been used in ornithological studies, because it provides biological data about these animals, their biology, and can be very important in the understanding of ecological and behavioral issues. The main purpose of the study was to investigate the concentrations of certain plasma biochemical parameters in nestlings of Rockhopper Penguins (Eudyptes chrysocome) at the crèche phase and the potential influence of some factors such as sex. We captured 95 nestling Rockhopper during the period 24–31 January 2017. All nestlings were randomly selected from colonies in Saunders Island (Falkland Islands). All the sampled birds were between 25 and 45 days of age, with mean weight of 1.778 ± 0.314 kg and mean bill length of 36.0 ± 2.8 mm. No differences in blood parameters or body condition between sexes were found. No parameters but total protein and urea were related to body index. Body index showed a negative significant relationship with urea levels in blood, with penguins in worse condition (those relatively lighter) showing higher levels of urea in blood than those that were relatively heavier. Same trend was observed for total proteins. Urea concentration in blood would be used as a tool in future studies, particularly in young Rockhoppers when they are in crèche phase, a period of high level of mortality mainly by predation. Plasma urea was the single variable that reflects the best body index and also has a rationale background explaining this relationship.
KeywordsNestling Rockhopper Crèche Blood chemistry Nutritional condition Urea Penguins Falkland
We thank the Falkland Island government and Fundacion Migres that supported the present study. We are especially grateful to David and Suzan Pole-Evans for their support of this project. Two anonymous referees and especially J. P. Robin greatly improved the first version of this paper.
Compliance with ethical standards
Conflict of interest
The authors declared no conflict of interest in this study.
Procedures used in this study comply with the current laws for working on the Falklands Islands, as well as with institutional guidelines for the care and use of animals (Spanish Council (CSIC) Ethical Committee). Permits to work in the study area and to take blood samples of Rockhoppers Penguins were granted by Falkland Government (number of license: R12/2014), as well as by the owners’ of the Saunders Island.
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