 During heavy rains , it was much more difficult to track insurgents by air , <unk> Portugal 's air superiority , and Portuguese troops and vehicles found movement during rain storms difficult . In contrast , the insurgent troops , with lighter equipment , were able to flee into the bush ( the <unk> ) amongst an ethnically similar populace into which they could melt away . Furthermore , the FRELIMO forces were able to forage food from the surroundings and local villages , and were thus not hampered by long supply lines . 
