Comparative Hematology and Plasma Biochemistry of Redtailed Hawks and American Kestrels Wintering in California

A•STRACT.--In December and January of the winters of 1990-91, 1991-92, and 1992-93, blood samples were collected from 52 Red-railed Hawks (Buteojamaicensis) and 91 American Kestrels (b•lco sparverius). Twenty-five blood parameters were measured, including white blood cell components, plasma enzyme activities, and plasma chemistry concentrations. Interspecific comparisons were made to identify species specific differences pertinent to health assessment. American Kestrels had a higher incidence of hematozoa infection, higher alkaline phosphatase and acetylcholinesterase activities, and higher plasma cholesterol, blood urea nitrogen, uric acid and sodium concentrations. Red-tailed Hawks had higher white blood cell concentration and eosinophil count estimates, aspartate aminotransferase and butrylcholinesterase activities, and a higher plasma albumin concentration.