Plasma chemistry and hematology reference values in wild nestlings of White-tailed Sea Eagles (Haliaeetus albicilla): effects of age, sex and hatching date

Studies on normal concentration of blood constituents of free-living birds are not very common. An adequate knowledge of blood chemistry is greatly recommended for those projects involving research and management of populations as far as they can be valuable for the assessment of the nutritional levels and health status of species. No previous published reports on these parameters from this species are available. The aim of this study was to obtain representative reference measures for hematologic and biochemical values in free-living clinically healthy wild White-tailed Sea Eagle nestlings (Haliaeetus albicilla). In addition, we investigated potential relationships between blood parameters, sex, age and hatching dates. Blood samples were obtained as part of routine monitoring and management when wild chicks were removed from their nest as part of a reintroduction program prerelease health check. A total of 83 nestlings, 43 males and 40 females, between 41 and 66 days of age (mean = 54.22, SD = 5.7), were sampled. Significant differences between sexes were found. Among hematological parameters, MCH, lymphocytes P and thrombocytes showed significant differences between males and females. In biochemical parameters, significant differences were found only in calcium, CK and LDH between sexes. No effect was found of age of the nestling when the sample was taken in any of the analyzed hematological parameters. No other significant relationships were found between biochemical parameters and other considered explanatory variables. Hatching date showed no relationship with blood parameters excepting urea. Urea was the only variable showing a strong relationship with hatching date, with those nestlings hatching later in the season showing higher urea concentration.