- In southern Arizona, the Nashville Warbler (Leiothlypis Nuficapilla) is primarily seen as a common migrant during both spring and fall - August to October is the peak time to spot them in Southern Arizona as they journey south to winter in Mexico ... the numbers peak between mid-August and late September - From April to May, a smaller but steady wave returns through the region heading to western breeding grounds - While the vast majority winter in Mexico, a few scattered individuals occasionally linger through the winter months in the low-desert riparian areas of southern Arizona - During migration, Nashville Warblers are highly adaptable but consistently favor shrubby tangles, oak thickets, and low branches of trees