Eosinophils were significantly lower in BAEA than in RTHA (P < .
Whereas, RTHA and GHOW reference values from birds in a rehabilitation setting in this study were similar to previously reported values, BAEA and COHA reference values differed, likely because of the stress of rehabilitation.
18) Reference values for H:L ratio have not been reported for GHOW, however, values in this study were similar to those seen in BAEA (9) and Harris's hawks (13) but higher than those seen in imperial eagles (Aquila heliaca adalberti) (32) and sharp-shinned hawks.
Likewise, values for BAEA in this study were comparable with reference values published for free-ranging birds, with a few slight differences.
Although no reference ranges for free-ranging or permanent captive BADO exist, the species appear to have a higher WBC and heterophil counts when compared with the closely related tawny owl, which may imply a more marked stress response in this species; however, their H:L ratio is similar to those seen in Harris's hawks (13) and imperial eagles, (32) and lower than those seen in BAEA, (9) so these results must interpreted with caution.
In this study, BAEA had a slightly higher H:L ratio, WBC count, and heterophil count compared with free-ranging BAEA, which would likely indicate a measurable response to the stress of rehabilitation in this species.
Cause Overall RTHA EASO COHA GHOW BADO BAEA BWHA Impact 62 60 72 80 17 83 0 67 trauma Orphaned 9 3 2 0 39 9 0 33 Entrapment 12 5 18 15 22 4 0 0 Predation 3 0 8 5 0 0 0 0 Gunshot 5 16 0 0 0 4 50 0 Other 9 16 0 0 22 0 50 0 Abbreviations: RTHA indicates red-tailed hawks; EASO, Eastern screech owls; COHA, Cooper's hawks; GHOW, great-horned owls; BADO, barred owls; BAEA, bald eagles; BWHA, broad-winged hawks.