Archive for July 23rd, 2012

It’s only been a few short weeks, but our first few tern chicks are already taking to the sky. Although adult terns may make flying seem effortless, a chick has a lot to do and learn before its first flight.

First off, you can’t fly without feathers. Tern chicks are hatched covered in fluffy down. While these soft feathers may be warm and provide excellent camouflage, they aren’t very aerodynamic. Over the  weeks, our tern chicks have been going from this:

To this:

To this:

Their wings will grow from less than 20mm long to almost 200mm, mostly by adding long sturdy flight feathers. Their adult wingspan will be close to two and a half feet!

The chicks also grow tail feathers, but they won’t get the long, pointed streamers that mark an adult tern. As a result, you can spot a fledgling by the stubby-looking tail, even if you can’t see the unique color patterns on its back.

All these new feathers need to be kept clean and tidy, so soon-to-be fledglings spend a lot of time preening:

The next step is to build up muscle. Flying is hard work and for the first part of its life, a tern chick doesn’t use its wings for much. To make up for this, tern chicks flapping even before their wings are fully grown.

And of course, before a strenuous workout, it’s always good to do a bit of stretching:

No, not all tern chicks are green. This chick is part of a provisioning study, so he’s been color marked.

Once all their feathers come in, tern chicks start working extra hard to get airborne. It’s actually quite common to see a chick’s weight drop significantly just before it fledges.

It’s not uncommon to see them taking naps, either. Hey, all that flapping is exhausting!

Finally, for some chicks it might take a little extra encouragement. This fledgling wandered onto a neighbor’s territory and finally got airborne as he was being chased away.

While flying is a big step, these chicks still have a lot of growing up to do. Fledglings must master the delicate art of landing, figure out how to fly with a flock, and learn to catch their own food. In the mean time they can be seen begging food from their parents and making cautious practice dives into the water.

Feed me! Feed me! Feed me!

Like the terns, we’ve only got a got a short amount of time left on the island, but I’ve got a post or two more up my sleeve before we say farewell from Ship Island.



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