I wrote some thoughts on this novella (from The Island of Doctor Death and Other Stories and Other Stories) on my Gene Wolfe blog here:
http://silkandhornheresy.blogspot.com/2011/03/tracking-song.html
I love this story. Does anyone know if it's referencing any myths or anything? And did you notice how it pre-references some themes from the Solar Cycle (such as vampire-bat-people, different sizes of humans, forgotten technology, etc.)?
-DOJP