Samples of exhaled breath and breath condensate were collected from 20 feral pigeons (Columba livia) while they were anaesthetised and intubated, and when they were kept unanaesthetised in an acrylic box. Samples were also collected from six chickens (Gallus domesticus) while they were kept in an acrylic box. The samples were analysed for pH, nitric oxide (NO), hydrogen peroxide and leukotriene B4. The volume of condensate collected from the pigeons was independent of bodyweight and significantly more (1·66 [0·64] ml/kg) was obtained while they were in the acrylic box than when they were intubated (0·87 [0·32] ml/kg). The mean volume collected from the chickens was 0·15 (0·06) ml/kg. Cooled samples had higher concentrations of NO than uncooled samples. The pH of the samples of condensate collected from birds in the acrylic box were significantly higher (7·9 [0·3]) than those from the intubated birds (5·3 [0·1]), and samples from the chickens had significantly higher pH values than samples from the pigeons (8·2 [0·2] v 7·9 [0·3]).