There's this frog, see. You've heard his story - swimming along in a pot on top of the stove, with the burner slowly cranking up to its highest setting. The water warms so gradually that the poor guy doesn't know he's soup until it's far too late.

Autumn is like that, only in reverse. The change from shorts and T-shirts to wool socks is so slow, we barely notice, especially when Indian Summer spikes the temperatures of an otherwise cooling trend.If we fail to note the seasonal transition, rest assured every whit of the natural world is paying attention. For everything from towering oaks to tiny spider mites, survival in a temperate zone like ours depends on being able to anticipate and adapt to the coming winter.Most noticeable - and most celebrated - of autumn's events is the movement of migratory birds. Some species are gathering now in huge flocks preparing for the trip. Others have already set off in predictable patterns over such well-known locales as Bake Oven Knob and Hawk Mountain Sanctuary.Migration patterns of raptors, waterfowl and songbirds are well known, having been observed and studied for years. But birds are not the only things to head south for the winter. Throughout Pennsylvania - indeed, throughout all of North America - bats and insects are packing their proverbial bags, too.Pennsylvania's bats feed almost entirely on moths, beetles and other insects. When temperatures drop below 40 degrees Fahrenheit, insects become less active. Faced with the impending food shortage, six of our area's nine bat species go into hibernation, and three others - silver-haired, hoary, and red bats - fly south just like birds.Some of these bats hibernate once they reach the southern U.S., while others actively pursue insect prey if temperatures allow. Not much more is known about their habits, though the Game Commission is undertaking some important research.Catching bats in specially designed "mist nets," and fitting them with tiny micro-transmitters, biologists hope to tease away at the migration mysteries. One project in the northwest corner of the state hopes to track bats around - possibly even over - Lake Erie.Understanding the movement of bats around the Great Lakes is crucial, as developers propose increasing numbers of offshore wind projects in the region. For reasons not well understood, the turbines pose a significant threat to migratory bats. The animals seem attracted to, and easily injured or killed by the spinning blades.Equally as remarkable as bat migration is the long-distance movement of insects. Monarch butterflies are a well-known example, but they're not the most widely traveled of Pennsylvania's insects.Dragonflies can cover amazing distances. The "wandering glider" for example, a large, golden-yellow dragonfly, is known to regularly cross the Indian Ocean, following monsoon rains from India to East Africa.Like raptors and songbirds, dragonflies are thought to follow natural landmarks along the way, and actually pack on reserves of body fat to power the trip.Nine species - including the wandering glider - leave Pennsylvania for points south. Unlike birds, dragonflies book a one-way ticket; those seen in fall migration are not the same ones to return. Instead, the next generation of insects completes the cycle, coming north to feed and breed in spring.Also unlike birds, most dragonflies tend to cruise at lower altitudes. High winds that aid in flight for hawks and eagles are far too strong for paper-thin insect wings. Lucky for us, this means migrating dragonflies are fairly easy to observe, sometimes flying just overhead.For tips on viewing and identifying wildlife in migration, stop in at Carbon County Environmental Education Center. CCEEC provides a full reference library, as well as field guides and binoculars available to visitors on loan.CCEEC also offers information on "citizen science" opportunities, where your personal sightings of birds and insects in migration can contribute to real world research. Email

cceec@ptd.net for details.