2.7.3 Exhaustion MacKenzie (1995) reported research conducted by Wageningen Agricultural University in the Netherlands which indicated that a major contributory factor to losses during races was weakness due to the conditions imposed on pigeons during transport to liberation points. Lack of drinking water, or the opportunity to utilise it, caused birds to dehydrate and overheat. Pigeons, thus weakened, were more likely to die on the race route. MacKenzie (1995) also reported that overheating may be exacerbated by overcrowding birds into poorly ventilated transporters. So they blame transporters