Naval aviation of Blue-tailed Bee-eaters

Lin Yangchen photographed three successive stages of dive sequences of the Blue-tailed Bee-eaters (Merops philippinus) as it zoomed into the water to most probably catch an aquatic insect or a fish.

“The first photo shows the bee-eater leaving its perch with the anterioposterior axis pointed downwards (but dorsal surface still on top), but with the head remaining horizontal (top left). I call this ‘gyroscopic’, and it is a behaviour exhibited by dragonflies in flight also – when they turn, they keep their heads horizontal. This way of leaving the perch does not necessarily lead directly to a dive – the bird may fly around the area first before descending to the water.

“A few milliseconds prior to impact with the water surface, the wings here are more swept back than those in Lee Tiah Khee’s photograph (top right). This could be because the bird needed to slow down and make precise adjustments to its trajectory in order to hit the fish accurately (in Tiah Khee’s case), while it can afford to hit at full speed and low accuracy in a bathing dive (my photograph). Another possible explanation for the difference is that my photograph was taken nearer to impact when the bird could have already locked on to its target anyway and could go all out with the afterburners for the kill. In the final moments before detonation, Tiah Khee’s bird could have swept its wings back. In any case, the two photographs bear a striking resemblance to the famous variable-geometry wings of the F-14 Tomcat. Record shot:

“The bird emerges from the water with anterioposterior axis parallel to direction of gravitational field, narrowly averting a mid-air collision with a MiG-35Hirundo tahitica (top left). But collision avoidance should be easier than it seems, because each bird is submerged only for a fraction of a second. Vertical emergence is probably more efficient because the bird presents less surface area to the water in the direction of travel (above right).

“In the takeoff from the water, the bird accelerates rapidly to cruising speed and altitude where all weapons systems (e.g. prey tracking, predator avoidance) regain full functionality (left).”