Blood Chemistry, Cytology, and Body Condition in Adult Northern Goshawks (Accipiter Gentilis)

A bird's physiological state contributes to its reproductive success and survival, yet few baseline physiological data have been published for wild raptors. Mean levels of protein, cholesterol, calcium, uric acid, aspartate aminotransferase, lactate dehydrogenase, and creatine kinase were measured in 29 Northern Goshawks ( Accipiter gentilis ) during 1998-99. None of these substances were significantly different between males (N = 8) and females (N = 2). Levels of all substances were highly variable among individual birds and unrelated to the body condition index (mass/wing chord X tail length X culmen length). Total white blood cell count estimates and differential white blood cell counts were not significantly different between the sexes. Of the blood cell measures, only the percent of heterophils and lymphocytes, and the ratio of heterophils to lymphocytes (H/L) differed between birds in good body condition and birds in relatively poor body condition. The H/L ratio has recently been proposed as a reliable measure of stress. Thus, variable H/L ratios between groups of wild birds may indicate differences in stress levels and overall health.