EFFECTS OF AGE AND CAPTIVITY ON PLASMA CHEMISTRY VALUES OF THE EGYPTIAN VULTURE

Despite the interest in blood chemistry for studying ecological and pa thological characteristics of birds, sources of variability such as ag e and captivity are poorly understood, and reference values usually ar e obtained from adult captive birds. We determined 15 plasma chemical variables for 164 free-living Egyptian Vultures (Neophron percnopterus ) of three age groups (nestlings, subadults, and adults), and for 9 ca ptive adults. Free-living subadults and adults exhibited identical pla sma chemistry values. Nestlings had significantly higher levels of cre atinine, urate, urea, triglycerides, calcium, phosphorus, and alkaline phosphatase (AP) than both free-living subadults and adults, but lowe r values of glucose and aspartate aminotransferase (AST). Captive adul ts had significantly higher levels of total protein, albumin, creatini ne, urate, cholesterol, calcium, phosphorus, and AST than free-living adults, which we attribute to differences in diet quality and physical activity. We conclude that future studies should consider age as a ma jor source of variability in avian plasma chemistry, and that results obtained from captivity should be used cautiously to interpret plasma chemistry in the study and rehabilitation of wild birds.