Here’s a pic of a whistle I’ve just made from a piece of stick that a guitar maker friend gave me years ago. The fresh cut faces are bright orange but fade fairly quickly to a purpley brown. Does anyone have any suggestions about the species?
That is beautiful! Gimme. 
Perhaps it’s a variety of Padauk?
If it’s one of your wonderful Aussie timbers, it could be most anything.
That fresh color does look like Padauk, but I don’t know about Padauk turning brown.
Its Bloodwood (Brosimum paraense). Also called Satine, Cacique, and Cardinalwood. From Brazil.
Casey
A handsome wood.
It does look like Bloodwood, but the Bloodwood whistles I’ve made haven’t turned brown.
I’m throwing in with Waltzingfool on this one. It looks like Padauk and behaves like Padauk. But who knows for sure? Padauk will appear anywhere from pinkish red to orange when freshly cut but will turn brown if exposed to sunlight. Finishes containing UV blockers are sometimes recommended to help retain its color. It is not unlike Purpleheart, Cocbolo, Yellowheart or Osage Orange in that regard which all darken somewhat with exposure to light. Bloodwood will darken too but it retains its reddish hue in my experience.
Feadoggie
My guess is “Brazilian Cocobolo”. It is very popular with guitar makers these days. Regional trees can vary in shade/color.
Cocobolo is not that uniformly orange. It generally is reddish brown with the occasional yellow, red, orange streaks. It does go to brown after a while. I turn quite a bit of it. And Thomas, I have not heard of a Brazilian Cocobolo although Cocobolo is a fair substitute for those seeking the color and grain of Brazilian Rosewood. Cocobolo generally is sourced in Central America. Nice stuff. I’m sticking with Padauk. But who knows for sure?
Padauk. That’s the general consensus any way, from here and another place. Thanks for all your suggestions!