Abstract
Background:
Wild animal rehabilitation enhances individual welfare and supports the long-term viability of wild populations. However, inappropriate practices can negatively impact the ecosystem or result in the animal dying after release. The scientific literature provides extensive documentation of care commonly applied in the rehabilitation of raptors (e.g., absence of injuries or diseases, hunting ability, and flight ability). However, others lack scientific support and have only been mentioned in essays and guides.

Aim:
This study involved developing a welfare and suitability assessment protocol for the release of raptors from specialized rescue and rehabilitation centres. The protocol evaluates whether birds entering rehabilitation are suitable for release back into the wild.

Methods:
To identify welfare assessment criteria for raptors, the Delphi method was used with a panel of 24 expert professionals with experience in raptor conservation and rehabilitation. They identified critical welfare indicators for the assessment and incorporation of birds into rehabilitation and release programs, including health, behavior, and injuries. Some indicators were selected, and others were discarded based on their applicability and relevance to a raptor center. Finally, a second survey of the same experts resulted in a theoretical welfare protocol for raptor rehabilitation prior to release.

Results:
Fifty-five indicators covering health, flight, treatment, feeding and behaviour were obtained, reviewed and evaluated by experts. Based on their experience, the experts discarded ten indicators as being either inapplicable or providing unreliable results for release. This resulted in a system of 45 reliable and applicable indicators for deciding whether to release a rehabilitated raptor (body condition, weight, lure feeding pattern, etc.). The first phase provides guidelines for validation in rescue centres to calculate the reliability, repeatability and reproducibility of the indicators and the instrument as a whole.

Conclusion:
Rehabilitation is often a lengthy process requiring thorough physical and behavioural assessments. It is irresponsible and detrimental to the animal's welfare to release individuals into the wild who subsequently die of starvation or are unable to adapt to an unfamiliar environment.

Key words: Birds of prey; Animal welfare; Rehabilitation; Pre-release; Indicators.