I'm searching for a source of nutrients for a nomadic tribe that climbs a seemingly endless metal tower. They have been climbing for generations and are too high up to see any ground below. The structure they climb is only made of metal (so far).
Their water comes from rain, condensation and maybe body fluids (however less advanced than in "Dune"). Their main food source is birds and other flying creatures they catch, collect and breed while traveling.
I realize there is no source for carbohydrates, vitamins and fiber in this diet. I read Nomadic Tribe of Herders - Source of Carbs/Other Nutrients?, but it seems every answer includes "They have to eat plants or agricultural products somewhen in the year", but I wouldn't know how the people could get these things.