The orange-bellied parrot (OBP, Neophema chrysogaster) is a critically endangered migratory parrot that breeds in southwest Tasmania. Fewer than 20 birds have been returning from migration in recent years, with the wild population augmented annually through the release of captive-bred birds. In February–March 2016, eight OBPs died at Adelaide Zoo. All birds had reduced body condition. Four birds had non-specific histological changes. Other birds variably exhibited bacterial sepsis, sinusitis, or aspergillosis. The mortality event was presumptively attributed to cumulative stressors in the flock. Intra-nuclear viral inclusions were identified in liver or kidney in three birds, with mild associated degenerative changes. Psittacid adenovirus 2 (PsAV2) was identified by PCR. Adenoviral lesions were considered secondary to underlying debility, not significant contributors to mortality. Movement of OBPs from Adelaide Zoo to other institutions was suspended pending further investigation. Surveillance for PsAV2 by cloacal swab of the remaining Adelaide Zoo OBP flock revealed a PCR prevalence of 39%; 53% in birds >1 year. Similar prevalence was subsequently detected in populations at other institutions. Four of eight free-ranging birds, recaptured after breeding, tested positive. PsAV2 was not detected in 29 native and exotic psittacines housed at Adelaide Zoo in aviaries with geographic or operational proximity to the OBP aviaries, including elegant parrots (N. elegans). PsAV2 is considered endemic in the OBP population, though does not appear to present a significant disease risk. The PsAV2 status of the population historically is under investigation. Monitoring of the virus in the captive and wild OBP populations is ongoing.
We thank the four other institutions participating in the OBP captive breeding program, and the Veterinary Technical Reference Group of the OBP Recovery Team.