h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

You say that the core of its range is the Kalahari.

I'm guessing that it's about 400 miles from one to the other. That's a pretty good range, assuming that this type of robin isn't a long-distance flyer.

Hello! Yes actually the range is even wider than that. I reckon there is some interchange over the long term between birds all over the range, they needn't fly very far on any one occasion to enable them to cover all this range over decades and centuries. The species shows no known regional variation, so some mixing must be going on.

Nothing wrong with that.

If not much is growing in the Kalahari, why is it part of their range?

or do they have to fly over it to get from one nice area to another?

(Probably a silly question, but all I know about the Kalahari I learned form "The Gods must be crazy." As, indeed, they probably are.

Camelthorn trees look interesting.

Actually as I said in the article the Kalahari is surprisingly well-vegetated! It's not nearly a barren desert. And even the most barren deserts we have, still have their birds! There's always food. In the Namib, which has almost no rain and almost no vegetation (but it does have some such as the amazing Welwitschias) has a thriving ecology that is based on edible bits and pieces blown in by the wind!

Sand from the Sahara gets blown across the Atlantic and affects Brazil.

Birds can bring seeds and nest materials.

Migrating animals leave their droppings, fertilizing the ground.

And the rain that does fall can push into a desert, bringing mutrients.

Nature is always on the move.

Yeah. In the Namib there are almost no rivers, but there are streams that flow intermittently, bringing water from more inland regions during years of above-average rainfall. These riverbeds are lifesavers for many kinds of plants and animals. Even in years when the river is not flowing, there's water underneath the desert sand. Deep-rooted trees can get this, and produce leaves, flowers and fruit eaten by animals. Elephants often dig in the riverbed until they've reached the water.