Analysis of clinical and hematological characteristics and search for hemoparasites in owls (Strigiformes: ‎Strigidae) seized or rescued from the Atlantic Forest biome of the Rio de Janeiro (southeastern Brazil)

Hemoparasitism is known to vary according to the presence of vectors and hosts, and hematological examination can be a useful tool for early diagnosis in avian medicine, contributing to monitoring and conservation of bird populations. In this context, we aimed to analyze the clinical and hematological aspects of free-ranging owls seized or rescued from the Atlantic Forest biome of Rio de Janeiro, Brazil. The animals, with or without clinical signs of diseases, were studied regardless of their age, sex, and physical status. Blood samples were collected and complete blood counts were carried out. Five different species were obtained in this study. These species were Megascops choliba (50%), Asio clamator (18.75%), Athene cunicularia (18.75%), Pulsatrix koeniswaldiana (6.25%), and Strix huhula (6.25%). Orphaned birds and traumatic injuries were the causes of admission to the wildlife rehabilitation facility. The search for hemoparasites revealed infection by protozoa of the genera Haemoproteus, Plasmodium, and Trypanosoma. We concluded that hematological findings in seized or rescued owls predominantly suggested the presence of stress or inflammation resulting from post-traumatic situations. The causes of admission were mostly due to human interference, which demonstrates to have a negative impact on the health aspect of owl populations in urban centers, such as Rio de Janeiro. Blood protozoa are circulating among the different populations of owls and although infection by Haemoproteus spp. and Trypanosoma spp. seems to trigger a low pathogenic potential, Plasmodium infection may indicate unfavorable prognosis, endangering wild species.