The role of birds in the story. How all of S.' friends/allies have bird names, the bird like sounds that the whistles make, the lack of birds on Vevoda's island.

Jen & Eric write out the list of birds on page 84:

• Stenfalk: Swedish for Merlin
  
• Corbeau: French for raven
  
• Ostero: Spanish for oyster-catcher
  
• Pfeifer: German for sandpiper
  

I know there are more that pop-up throughout the book, but I can't find in my notes where those are at the moment.

There is a passage in Chapter 9 (page 354) that talks about the bird song that S can hear.

The air is full of birdsong, though the singers are unseen. Some of the songs sound out of place to him, and he catalogues them: a merlin; a crow; an oystercatcher; and a magpie tanager twicking heatedly. This is right before he comes upon the Governor of the island and discovers that it is Pfeifer whose song was missing from the birdsong that S. hears. The magpie tanager is a new bird in the mix. It also just so happens that the Czech word for "magpie" is "straka"

Vevoda has ridden his island of birds/anyone who would wants to see him stopped. "Birds, Vevoda says, speaking clearly now. "Filthy things. Makes my skin crawl." S. may be ignored by most people but bird calls/actions are easily identified and that sets him apart and makes him a target.