Canary

Canary: A name for any soldier wearing a yellow ; an instructor at a gas school, or one of the Sanitary Corps of the RAMC; also the battalion Sanitary Orderlies attending to incinerators, latrines etc., work for which men were usually detailed for punishment.

Canaries (the birds) were used in the war by the Royal Engineer Tunnelling Companies as gas detectors, being quickly affected by the presence of gas, otherwise imperceptible, in the mine galleries. An officer tells this story of one bird: Twice a particular bird gave the necessary warning by dropping off his perch. Having recovered on both of these occasions, he evidently considered he had 'done his bit,' as on the next and future visits, he habitually fell off his perch immediately he entered the gallery, although there was no suspicion of gas. Consequently the bird had to be relieved of future duty, and took his place as the Commanding Officer's pet.