24 March 2010

A couple of hours from Ashmore Reef over dizzying water depths of a kilometre or so, we started to cross shimmering lines of calm water in the rippled sea surface. These tell-tail signs of upwelling are a sure indication of something remarkable about to happen and so it was we spotted flocks of wheeling birds on the horizon. Boobies!

Watching juvenile Brown Boobies near Middle Island

With tapered wings and binocular vision, both Brown and Red-footed could be seen diving like javelins into the sea. Then almost inevitably, someone on the spotting scope cried “dolphins” as one or two were seen leaping beneath the birds in a frenzy of feeding.

Flying fish began to launch ahead of the boat as we lazily (for there is no other way at sea in the tropics) made our way forward. Anticipation built as we approached the kill zone, all the time flanked by more boobies making their own way alongside us.  Our method of finding our chosen quarry at sea is not that different from the seabirds. Red-footed Boobies, Wedge-tailed Shearwaters, Sooty Terns and even sharks and flying fish parade in lines along these surface lines, where nutrients from marine snow fall eons before, resurfaces to form a soup of plankton.

On approach, we were treated to a large pod of Bottlenose Dolphins, that chose to ride under the bow of our vessel. You could even hear them whistling beneath. Typically apprehensive Spinner Dolphins porpoised ahead and with a moment of notice, a few Melon-headed Whales were seen, then a Rough-toothed Dolphin and finally the characteristic wake of white-water behind a fast-moving pod of Fraser’s Dolphins. What a sight!

The Boobies are expert flying fish hunters, often catching them on the wing. At the heart of this feast however, was a mass of fish, coralled into a ball by dolphins and tuna below, pushed to the surface and then struck from above by the seabirds.  This performance occurs time and time again offshore, revealing the hidden connections in the ecology of these different species. The seabirds couldn’t survive if it were not for tuna and dolphins raising prey to the surface. Maybe even the dolphins and whales, with eyesight like our own, leap from the surface and glimpsing flocks of birds, to make their own pursuit.

It is these moments that make trips like this so special but it is hard to know when to even take a toilet break! The next exciting encounter could happen any second.

Look at past trip reports: http://aussiebirding.wildiaries.com/trips/210 | http://aussiebirding.wildiaries.com/trips/95