Hole Nest in Ground

Very few birds nest within holes in the ground.Nesting in hole  seems to be a better strategy than nesting in the open.We survey around 100,000 eggs and found that non-hole nesters averaged 48% rearing success while hole nesters averaged 74%.The main reasons seems to be eggs within holes in the ground are better protected against adverse environmental conditions and from predators.The hole nests can be  open onto a cliff edge or a vertical edge of a river bank,Road cuttings and those holes in relatively flat ground.Some birds dig the holes themselves and some uses the already existing holes.Birds making this types of nest are green bee eater and all king fishers.Green bee eaters make almost 1 meter hole in flat ground as well as edges to lay their eggs.