Aspergillosis in hihi (Notiomystis cincta) on Mokoia Island

Aim. An intensive 2-year field study of 65 hihi (or stitchbirds) on Mokoia Island provided an opportunity to investigate the causes of mortality of th is endangered species in a free-living environment. Methods. The birds were observed daily during the breeding season (October to March) and every 4 weeks during the remainder of the year. Any abnormali ties in behaviour, voice and body weight were recorded and all sick or dead birds which could be recovered were taken to the laboratory for necropsy. Results. Thirty-one birds died during the period of this study. Aspergillos is was found to be the cause of death in six of nine adult birds examined p ost mortem. Some of the affected birds experienced subtle voice changes bef ore becoming ill and all birds had granulomatous lesions in airsacs or lung s at necropsy. A further eight birds for which carcasses could not be found or which were autolysed showed similar clinical signs before death or disa ppearance. Conclusion. Because Aspergillus is an opportunist pathogen it seems likely that affected birds were immunosuppressed. This may have occurred during th e breeding season which in this species is highly stressful. The presence o f fungal material in bronchial exudate and the occurrence of the disease in mates, raises the possibility that aspergillosis in hihi may be contagious .