Friday, June 8, 2012

Riders on the Wind

A cloud of frigatebirds over North Beach
On a puff of wind the large, iridescent black shapes float past, slowly gaining altitude as the warm air updrafts, or thermals, lift them higher and still higher into the atmosphere.  A slight adjustment to the tilt of a wing, the position of the tail and the bird effortlessly climbs higher still. 

Dozens of frigatebirds glide past our house joining the hundreds that are arriving from all directions.  They enter the thermal spiral, sliding in place without interrupting the flight pattern of others - all playing, soaring in the updraft.  I lean backwards, craning my neck into an uncomfortable position, trying to count the birds.  It's an impossible task with hundreds more joining in.  The spiral looks to contain a thousand or more black birds, soaring, gliding, spinning upward until they are mere specks in the sky. 

3 feet tall, and a wingspan of up to 7 feet
These enormous birds stand about 3 feet tall (about a metre) and have wingspans of up to 6 1/2 feet wide (about 2.3 metres).  The females are black with white underbellies, and the males are black with a bright red throat pouch that during mating season is inflated to attract a female.  Groups of males will put on a spectacular courtship display with their throat sacs inflated, clattering their bills, bobbing their heads and quivering their wings. 

Apparently it works - the females think they are quite handsome.  The pair will remain monogamous for the season.  Both parents share in feeding the one or two chicks for the first three months.  Then the chicks will stay another eight months with the mother, noisily demanding to be fed even though they are nearly as big as the parent.

Coordinated flight paths over Ray carcas, discarded in surf.
Unlike most ocean-going birds, the frigatebirds can't swim, can't walk well on land, and have difficulty taking off from a flat surface - but, they can stay aloft for more than a week at a time flying as much as 225 kilometres before they land.  When hunting over the ocean surface they snatch small fish, or baby turtles, using their long, hooked bills. 

When food is plentiful, the birds aren't aggressive with each other.  We have seen them coordinate their flight paths - flying in an orderly pattern from right to left over a ray carcass, picking off bits of meat.  Not squabbling, but cooperating.  All of them feasting. 

Flying in a pattern, right to left. Everyone eats!
Other times they perform like fighter pilots, using speed and manoeuvrability, attacking the another frigatebird until the food is dropped mid-air.  I have had the experience of a bright blue still-flopping fish landing beside me - the lost prize from a battle between two frigatebirds.  I put it back in the ocean, but the drop from several hundred feet guaranteed that it was not going to live.  It flipped over on its side, stunned, not moving. 

Unfortunately the two squabbling birds had lost interest in the hapless fish, and had moved on to another battle.

Peace returns when the updrafts are perfect, and another 'fly-in' begins. 

The birds once again start drifting past, slowly gaining elevation. 

Heading up, up and away.  Like Peter Pan and Wendy.

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