What is an axe beak’s travel speed in Icewind Dale?

Icewind Dale: Rime of the Frostmaiden gives travel speeds for dogsleds, snowshoes, and on foot (p. 11). On the same page, it says that dogsleds, at 1mph, are the fastest way to get around in the Dale.

However, this section says nothing about axe beaks, which p. 20 offers as a travel option. How fast would these travel?

My gut says if they are speedier than sled dogs (50 vs 40 feet per round, per MM), they might run 1.25 mph. Is this the best/proper way to calculate it? How does this reconcile with sled dogs being the fastest travel method (p. 11)? Do sled dog rest requirements (1 hour after an hour of pulling, p. 20) factor into the answer at all?