Hematology and blood chemistry values in free-living imperial cormorants (Phalacrocorax atriceps) during breeding

GALLO. L. ; QUINTANA, F.; UHART, M.

San Pablo

Congreso; Primera Reunión Bienal de la Sección Latinoamericana de la WDA (Asociación de Enfermedades en la Vida Silvestre); 2013

During reproduction, birds experience seasonal changes in their energy demands and feeding requirements according to their breeding duties. These changes may be reflected in variations in their physiological parameters. Male imperial cormorants (IC, Phalacrocorax atriceps) share egg incubation with females and have an extended period of parental investment until the independence of chicks. They play an active role in nest defense, brood care and chick feeding activities. During the 2010 breeding season we collected blood samples from adult male IC at the Punta León colony in Patagonia Argentina, during the late incubation period (n=23) and before chicks fledged (n=20). We established baseline values for hematological parameters and serum chemistries and explored changes in these parameters between sampling periods, considering recaptured birds (n=16). All birds appeared to be in good body condition and no abnormalities were noted during physical examination. In general, values for the parameters reported in this study were similar to those previously described for other cormorant species. Between sampling periods, significant differences were found in glucose levels (paired t-test=-3.57, df=15, p=0.003), which were higher prior to chick fledging. Bird glycemia can vary due to circadian rhythm; however all individuals in our study were sampled at the same time of day, before foraging trips, and having fasted for over eight hours. Hyperglycemia can be a result of stress; thus higher values found in our study may have been a response to increased stress during the chick-rearing period, when males show higher nest-defense intensity. This study, coupled with previous reports on pathogen exposure in IC from Patagonia, contributes to our knowledge of the overall health status of this species. Since no differences were found in most physiological parameters between sampling periods, we recommend that health monitoring of adult IC should be performed during the end of the chick-rearing period, when adults are less likely to abandon their nests.