He watched a succession of wavelets lapping at the sloping roof, wishing that be could leave the Colonel and walk straight down into the water, dissolve himself and the ever-present phantoms which attended him like sentinel birds in the cool bower of its magical calm, in the luminous, dragon-green, serpent-haunted sea.

The alligators congregated like hounds around their master, the wheeling cries of the dense cloud of sentinel birds overhead, nile plover and stone curlew, piercing the morning air.

The sight of a raptor results in a rallying call by sentinel birds and subsequent coordinated mobbing of the intruder.

The sentinel birds fall silent.

When foraging the sentinel bird calls with wing fluttering and hopping.

When all is safe, another distinctive call from the sentinel bird sends all the others to the pool where their daily water needs are taken up within about fifteen seconds.