Haematology and biochemistry reference intervals of Galapagos short-eared owls (Asio flammeus galapagoensis) from Floreana Island.

To limit the impact of invasive predator species on the ecosystem of Floreana Island, Galapagos, a large-scale rodent eradication program was implemented. Due to the significant risk of secondary exposure to rodenticide, a mitigation tactic was used to protect the only native raptor found on Floreana, the Galapagos short-eared owl (Asio flammeus galapagoensis). A large proportion of the owl population was brought into human care in July 2023 with the goal to release back to the wild following the completion of the eradication program and reduction of the risk of exposure to rodenticides. During this time under human care, health examinations including blood collection for assessment of haematology and biochemistry parameters were completed. Descriptions of leukocyte morphology and population-based reference intervals (RI) are reported here utilizing results from 62 clinically healthy adults. Sex was determined using polymerase chain reaction, allowing for comparisons between males (n = 29) and females (n = 33). Statistically significant differences were found for several parameters: packed cell volume, relative and absolute monocyte counts, total protein, calcium and phosphorus levels were higher in females, while uric acid and glucose levels were significantly higher in males. These baseline RI are an important tool for assessment of this unique population while under human care, and will allow for comparisons and continued health monitoring after release back to the island of Floreana.