The Gough bunting (Rowettia goughensis) is indigenous to Gough Island and critically endangered due to predation by invasive house mice (Mus musculus). A planned ecosystem restoration by eradication of house mice via aerially delivered rodenticide requires a reproductively balanced population of Gough buntings being held in captivity to avoid primary and secondary poisoning. To aid disease detection during the period of captivity, Gough buntings (n = 25; five adult females, 15 adult males and five juveniles) were captured, measured and sampled to determine reference ranges for routine haematological and biochemical parameters and to identify any faecal bacterial species and intestinal and haemoparasites. Adult females had significantly higher blood glucose (P = 0.02 and 0.05 for different analyzers) and globulins (P = 0.02) than adult males or juveniles, and juveniles had consistently higher, although not significant, concentrations of creatine kinase. Juveniles had significantly (P = 0.007) more heterophils than adults; eosinophils were rare in adults and absent in juveniles and azurophils were absent from all individuals sampled. No parasite eggs were found in the faeces and no haemoparasites were found in blood smears. Several faecal bacterial species were recorded including Enterococcus spp. (n = 12), Klebsiella spp. (n = 7), Staphylococcus aureus (n = 6), Staphylococcus intermedius (n = 1), Escherichia coli (n = 1) and Pseudomonas spp. (n = 1). No overt clinical or subclinical disease was found in any of the birds examined, which suggests they are suitable for short-term captivity during ecosystem restoration and the data will provide key haematological and biochemical reference ranges for monitoring their health. However, the capture of a reproductively balanced population may require significant effort due to the relative difficulty with which females were caught.