Murals carved of Rowlet early in Alola's history surprisingly depict them as active hunters in sunlight, who chased down other diurnal pokemon such as Ledyba and Paras. Even more surprisingly, the murals depict Rowlet quite frequently; they are more omnipresent than even Pikipek. These carvings, however, vanish within a couple generations of Alola's initial human settlement; it is not until three centuries later that depictions of Rowlet, now under moonlight, reappear in the archaeological record.
It is generally believed by students of natural history and archaeology that Rowlet were diurnal before the arrival of humans to Alola, and narrowly avoided the fate of many flying pokemon species throughout the islands of the pacific. Meowth and Rattata who traveled on human ships fed on many a Dartrix egg or helpless chick while their parents slept, until the Rowlet were all but eliminated. An extreme genetic bottleneck demonstrates just how closely this species approached extinction: all Rowlet alive today descend from a mere 16 breeding pairs, who lived about a thousand years before the present.
But a small minority of Rowlet hatched with eyes as adept as a Hoothoot's in the dark, and learned to fight back, leaving their predators to chase easier, less nocturnal prey. Intense selective pressure transformed Rowlet into a noctural species, and the humans who had once inadvertently nearly doomed them all learned to prize them as partners. Wild Rowlet ultimately disappeared due not to predation but from domestication - for in the age before the monarchy, back when Alola was divided into warring chiefdoms, there were few things more valuable than a loud pokemon who could guard villages and armies alike from surprise raids at night.