EC Regulation 1099/2009, On the Protection of Animals at Killing Regulations (PATOK), requires the severance of “the 2 carotid arteries” to ensure each animal dies rapidly (Annex 3, 3.2.). This requirement applies to stunned, nonstunned, manual, and automated methods of killing. I observed the severance of carotid arteries in nonstunned, religious slaughter in a study of 250 nonstunned chickens. The birds were checked for aversive/anger-type behaviors at 10 and 30 seconds and for the absence of corneal reflexes at 60 seconds after incision. Prolonged survivors were observed at 90, 120, 150, and 180 seconds after incision. Spontaneous behaviors in nonstunned birds surviving over 90 seconds were recorded on a digital videocamera. At postmortem, neck wounds were inspected for severance of blood vessels and the findings were photographed. The studies were carried out by observing single birds, on a line running at less than 400 birds per hour, where meticulous technique was used. Of these nonstunned birds, 225 of 250 died at or before 60 seconds and 25 of 250 showed behaviors prolonged for more than 90 seconds after incision. These 25 birds had one or more intact carotid, as follows: 11 birds had 2 intact carotids, 2 birds had 2 carotids and 1 jugular intact, 5 birds had 1 carotid and 1 jugular intact, and 7 birds showed a single intact carotid. This failure to sever the brain's blood supply may be linked to prolonged or resurgent, aversive or anger-type behaviors. Aversive/anger-type behavior was found in all checked birds from 10 seconds to over 40 seconds after the incision of both carotids and both jugulars, before death at 60 seconds. The prolonged fear/anger-type behavior over 90 seconds indicated a risk of consciousness and sensibility. I offered individual instruction on improved carotid severance techniques to religious slaughterers to avoid these risks to bird welfare. This welfare at slaughter study was compared to cattle and sheep work previously undertaken.