Poultry are highly susceptible to heat stress, and climate change is increasing the frequency and severity of heat events that kill millions of birds annually.
Heat stress in poultry causes acute suffering — birds pant, hold wings away from their bodies, and crowd near water points. Severe heat stress causes rapid death from hyperthermia, but chronic mild heat stress causes prolonged suffering including reduced immune function and behavioural disruption. The intensification of poultry production in hotter climates and the increasing frequency of extreme heat events make this a growing welfare crisis. Improved ventilation and shade are essential, but lower stocking densities and outdoor access on cooler days also help.