Insectivores such as swallows, wagtails and flycatchers have already headed south from Central Ostrobothnia and other parts of central Finland, reports the ornithological association BirdLife Finland.
Thrushes and waxwings left northern Finland early because of a berry shortage.
The only birds now actively migrating are geese and other waterfowl. The main migration of swans is not expected until November or December. During recent mild winters, swans have still been seen in January in sea areas that have remained unfrozen. Mice Seeking Winter Homes
Meanwhile there are plenty of rodents around this autumn. Naturalists say that moles and mice appear to be at the peak of their usual three-year population cycles. This is the time of year when mice begin moving into human habitations, finding access through holes and cracks of as little as one centimetre across.