Public transport from Navarrenx

Don't have any details Rob, but I imagine it must be possible. But are you sure it is this section you want to skip? I thought the few days walking through this Basque region, in the rolling hills as you approached the Pyrenees, were particularly beautiful and interesting. Places like Eauze and Nogaro I would rather skip, but I don't know how much transport there is out of places like Condom to say Aire-sur-l'Adour to let you skip this section.
Margaret