BANOS, Ecuador (AP) - Tungurahua volcano, which looms over the tourist town of Banos, could erupt any day, the government said Saturday as it began evacuating nearby communities. Authorities said increased volcanic activity had forced them to declare an orange alert, which meant the mountain could erupt within days or weeks. For a month Tungurahua had been under a yellow alert, predicting an eruption within weeks or months. Officials said at least 12,000 of the 25,000 people threatened by the volcano already had left the area. One hundred buses were evacuating the remaining inhabitants Saturday. For several days, the volcano has been expelling  gases, steam and ash, which has fallen on nearby villages. A government census revealed Thursday that ash had caused 40,000 chickens to die of respiratory infections.