All a twitter

WHY have huge flocks of budgies suddenly appeared around Alice Springs?  

birds

IT'S a surreal experience to have 15,000 budgerigars flying around your head, says photographer Peter Carroll.

"It's like a tornado," he marvels, "a green and yellow vortex that wheels around the sky like a single, giant organism." Then there's the noise: who knew that such tiny wings could sound like thunder?

Carroll photographed this flock at a dam 20km south of his home in Alice Springs. It's one of many huge aggregations, some containing 60,000 budgies, that have suddenly appeared around town.

What's going on? Local birdwatching guide Chris Watson says it's a classic example of a "boom and bust" desert life-cycle. Budgies eat grass seeds, and as long as there's enough food and water around they'll breed constantly. Since the rains returned in 2009 and brought the desert back to life, they've been out there multiplying in colossal numbers - but no one's noticed because they've been spread over a vast area. This year, though, the region has had a long dry spell (by late September the Alice Springs BOM station had logged a record 157 consecutive days without rain) and all those little clay pans in the desert have dried up. This has forced the budgies to seek permanent water sources, concentrating their numbers at a few dams around town and in the waterholes of the nearby West MacDonnell Range.

These mega flocks occur only at the crack of dawn, when the birds come en masse to drink before dispersing to forage. Falcons and kites have now started to appear in numbers, too, looking for a meal. The sight of these raptors swooping through the budgies brings another vivid metaphor to mind for Chris Watson. "It's like sharks attacking a shoal of fish," he says. "It's an incredible sight."