Restraint in a confined space, such as a cage or a box, may be perceived by birds as a stressful condition. Some concern has been expressed about restraining homing pigeons (Columba livia) in transport crates for sport or for scientific research. Therefore, this study sought to test whether short restraint time in a transport crate for 1, 2 or 18 (overnight) h causes oxidative stress in homing pigeons and whether it is more stressful than flying. To isolate the effect of crowding from that of transport per se, the pigeons were kept in an immobile crate, that is, without any movement. To quantify oxidative stress, we measured serum levels of oxidative damage (ROMs) and of antioxidant capacity (OXY). We found that pigeons restrained in transport crates showed no significant variation for both markers of oxidative stress, regardless of the duration of restraint. Conversely, pigeons which had flown around 200 km had increased levels of oxidative damage and decreased levels of serum OXY, both clear manifestations of oxidative stress. These results suggest that maintaining homing pigeons in transport crates for a short time (i.e. 1-18 h) does not cause oxidative stress.