California Condors (Gymnogyps californianus) are critically endangered and their existence is due largely to massive field-based and captive conservation efforts ongoing since the 1970s. In spring 2023, the condor population that occupies northern Arizona and southern Utah experienced a deadly outbreak of highly pathogenic avian influenza (HPAI) that killed ~21 birds and sickened others. To protect condors from this threat, we evaluated safety and immunogenicity of an inactivated reverse genetics vaccine that expressed the gyrfalcon/2014 2.3.4.4c hemagglutinin protein and that was originally developed for use in poultry. To ensure that the vaccine would not result in adverse reactions for this critically endangered species, two months after the first condors died, we initiated a trial in a surrogate species (Black Vultures, Coragyps atratus), comparing administration of a single 2x dose to a standard two-dose vaccine protocol.  Preliminary analyses suggest that most birds responded immunologically to the vaccine after two doses with no serious adverse reactions. Subsequently we conducted a trial with captive California Condors. Again, preliminary analyses suggested no serious adverse reactions and good immunological responses. Based on these results, a two-dose vaccination protocol was initiated for free-flying California condors. This work shows how interdisciplinary, interagency teams can work together towards conservation of critically endangered species threatened by emerging infectious diseases.