THE BURROW-EXCAVATION PHASE IN THE BREEDING CYCLE OF THE SAND MARTIN RIPARIA RIPARIA

摘要: Summary. Observations were carried out at a Sand Martin colony in working sand-pit, where fresh burrows have to be dug each year. Martins arrive the breeding pit from migration unpaired, and their social organization is then its lowest. Burrow excavation occurs only as climax form of group display. Digging communal character, number holes roughly equal individual birds present. The mounting excitement mutual stimulation display period induces which begin build nests lay. This produces close synchronization seems necessary condition for behaviour during rest cycle.