The Sand Martin is interesting in that it is capable of sustained flight from the first time that it launches itself from its nest hole. This is necessary for a Sand Martin to survive as, traditionally, the nest hole was, and often still is, in a sheer cliff face, often above water. It gains this ability over a number of days by flapping its wings vigorously in the nest/hole to strengthen them, then pressing its primary wing feathers and tail hard down onto the nest/hole at an angle of 45 until it is able to support its body by these alone. When it is able to support its body by its wings and tail alone for more than a few seconds, then, instinctively, it will launch itself from the nest hole.
: Edward CowleyBibliographic Citation
: Cowley, E.1977.The hand-rearing of Sand Martins. The Avicultural Magazine Vol.83.No.4.185-188