Ultrasonographic Assessment and Ocular Biometry of Brown Hawk Owls (Ninox scutulata)

Ocular trauma is a significant contributor to mortality in wild birds, particularly in owls. Despite the critical role of vision in survival, ocular biometric data for brown hawk-owls (Ninox scutulata) remain limited. This study establishes ultrasonographic reference values for ocular structures in the brown hawk-owl. Using B-mode ultrasonography, biometric parameters including corneal thickness, anterior chamber depth, lens thickness, vitreous chamber depth, axial length of the globe, and pecten oculi height were measured in 64 eyes from 32 individuals (26 adults and 6 juveniles). Correlations among these ocular biometric parameters were also analyzed. No significant differences were observed between the left and right eyes or between the horizontal and sagittal imaging planes. However, significant biometric differences were found between adult and juvenile owls, except for pecten oculi height. No significant correlations were identified between body weight and most ocular biometric parameters, except for a slight positive correlation with anterior chamber depth. Axial globe length showed positive correlations with anterior chamber depth, lens thickness, and vitreous chamber depth. Establishing normal ocular biometric values may enhance diagnostic accuracy and will serve as a valuable reference for veterinary ophthalmology, wildlife rehabilitation, and species conservation in brown hawk-owls.