Post-Release Survival Success of One-Eyed Great Horned Owls

Principal Investigator: Sara Childs-Sanford

Department of Clinical Sciences
Sponsor: Sarah K. de Coizart Perpetual Charitable Trust
Title: Post-Release Survival Success of One-Eyed Great Horned Owls
Project Amount: $60,000
Project Period: February 2020 to January 2021

DESCRIPTION (provided by applicant): 

Ocular injures are extremely common in owls. The decision whether or not to release an owl with one eye back to the wild has long been a topic of debate within the wildlife medicine and rehabilitation communities. Some organizations do release them, with the presumption that nocturnal owls rely predominantly on their extremely well-developed sense of hearing to locate and capture prey. Conversely, others euthanize these patients or resign them to a life of permanent captivity out of concern that they will not survive well if released. Which is the correct answer? Currently, this knowledge gap affects thousands of owl patients presenting to wildlife hospitals each year. Depending on which pathway is correct, owls may either be released with one eye and suffer in the wild, or are unnecessarily either killed or kept in permanent captivity. Our research aims to fill this knowledge gap by investigating the post-release survival success of great-horned owls with one eye. To do this, we will follow both normal and monocular owls for approximately 1 year to evaluate their survival rate, using non-invasive satellite tracking devices. We hypothesize that adult great horned owls that have had one eye removed and retain one normal functional eye will have a similar post-release survival rate as great horned owls released with two normally functioning eyes.

The practice of rehabilitation of native wildlife occurs globally and on a large scale. Despite this, little effort has been dedicated to determining the effect of case outcomes and release on the long-term health and survival success of patients. Evidence to support or refute commonly practiced rehabilitation measures is critical to maximize successful practices and minimize negative outcomes. This proposed study will investigate a common practice in wildlife rehabilitation in order to determine its validity, and more accurately inform rehabilitation and release practices for the great horned owl and other nocturnal owl species, thereby improving the health, welfare, and conservation of these commonly treated wildlife patients.