It is with great sadness that we report the passing of Dr. J. Lindsay Oaks, College of Veterinary Medicine at Washington State University, after a brief battle with an aggressive neuroendocrine tumor. Lindsay was a close collaborator and longtime friend of The Peregrine Fund, first involved as a teenager in the 1970s with the captive breeding and restoration of endangered Peregrine Falcons. He subsequently qualified as a veterinarian and specialized in veterinary microbiology. He may be best known for his role in 2000–2003 helping us discover that veterinary diclofenac was the primary cause of mortality that drove the catastrophic decline of Gyps vultures in South Asia. He also worked with us to discover and prevent a viral agent causing mortality in captive Aplomado Falcon chicks in the mid-1990s, and in 2008 to expose lead from spent ammunition, a fatal element in food consumed by California Condors, as a contaminant also of processed venison consumed by humans. He advised us on everything from West Nile virus to highly pathogenic H5N1 bird-flu, and how to respond to these threats. His interests and collaborations go well beyond these accomplishments; he will be missed by many.