There doesn't seem to be an obvious line separating summer from autumn. We'll get some cool, crisp, sunny days and say, ''Yay! Fall is here." Then, next thing you know, it's sultry, raining and humid -- kind of like this past week. It feels like summer again, and fall seems a long way off.

Nature knows better. When you visit the parks in the Preservation Parks of Delaware County system, you'll see nature unfolding in many ways. Leaves are turning color, and many flowers have been replaced by seed heads or berries (winter food for birds and other creatures).

There's an "autumn" aroma in the air; foliage that used to be vibrant and green smells different when it fades to dry and brown, as it prepares to enrich the woodland or meadow floor.

Squirrels and birds are very busy, instinctively preparing for cold weather. I've been hit by a falling nut more than once, while squirrels run up and down branches overhead.

Every day is a great day to visit the parks (after all, they are part of the environment we are trying to save through green living), but fall is a time when all your senses become especially engaged. Listen to the leaves rustle; smell the change in the air; feel the cool breeze; see the beautiful oranges, reds and yellows!

Our naturalists are leading a couple of upcoming programs that will really help you appreciate fall:

This Saturday, Sept. 26, join us for "Leaves Before They Fall," at Char-Mar Ridge Preserve, 7741 Lewis Center Road in Genoa Township. The hike begins at 4 p.m.

Then, on Saturday, Oct. 3, you'll learn what birds and animals will be eating this winter during a "Fall Forest Food Hike," at Emily Traphagen Preserve, 5094 Seldom Seen Road near Powell. That program begins at 5 p.m. Both programs are FREE!

Visit www.preservationparks.com for more information.