Swamped

This would have been easier if you'd paid more attention to the animals out here. But what with one thing and another, you haven't had much time to familiarize yourself with them.

So the first thing you can think of he might ride is a wild desert-horse, even though you haven't seen any around. And you couldn't help but notice that the two you've got in camp were shedding. It must be the season for it.

Which means if that's what Rider did, you should be able to find some stray hairs. They don't exactly stand out against the sands, but it's something. So you look down carefully...

And find a nest. With rather large eggs in it. Eggs which are much larger than the dozen or so lizards standing around watching them.

This is definitely Rider's work. You don't know how he does it, but you can't imagine anyone else doing this. Whatever laid these eggs is his ride, and he probably persuaded the lizards to watch the nest until the parent returns.

Which is all well and good, but how does it help you track him?