Quantitative and qualitative characteristics of blood cells in black-shouldered, Brahminy, and black kites

Black-shouldered kites (BSK, Elanus caeruleus), Brahminy kites (BrK, Haliastur indus), and black kites (BK, Milvus migrans govinda) are medium-sized hawks found in Thailand, and little is known about the hematology of these three kite species.

This study reports basic hematologic values and describes the light microscopic, cytochemical, and ultrastructural characteristics of blood cells in these kites.

Blood samples were collected from 113 healthy kites (50 BSKs, 53 BrKs, and 10 BKs) from January 2012 to December 2017. Complete blood cell counts, cytochemical staining (Sudan black B, peroxidase [PO], periodic acid-Schiff, α-naphthyl acetate esterase, and β-glucuronidase), and transmission electron microscopy were performed using standard methods.

Hematology, morphometry, and cytochemical staining patterns of blood cells were tabulated. BSK erythrocytes were smaller than BrK and BK erythrocytes. Heterophils, the largest granulocytes, were the most prevalent leukocytes in all kites. Cytochemical reactions in blood cells from these three kite species were the same, except that heterophils from BrKs were the only cells positive for PO. The ultrastructure of heterophil and eosinophil granules from the BSKs were similar in their homogeneous electron densities but differed in shape. The eosinophil granules from BrKs and BKs revealed heterogeneous electron densities with central pallor in some granules. Basophils had different granular electron densities, and some granules were electron-lucent.

The 23 baseline hematologic values and morphologic, cytochemical, and ultrastructural characteristics of all blood cell types in this study provide reference data for future kite healthcare.