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It is interesting to speculate that if you were dropped into an area without knowing where, whether you could predict from the animals and plants observed not only where you were but what time of year it was. Certainly this is fairly easy for geographic areas that you are familiar with. Indeed even without access to a calendar you should be able to judge the season/month fairly accurately. The end of summer provides a number of such clues.
The ripening of fruit is certainly a reliable means of judging the month, subject to some variation in the weather. I watch the changes in the flowers and fruits of ginseng over the summer and the bright red fruits shown in the photo indicate that it is mid to late August in our area of SW VA at an elevation of 1500 feet. Since migrating thrushes will be passing through very soon, they should find these ground level red fruits very attractive, as they do the bright red fruits of spicebush and cucumber and Fraser magnolias.
A fruit of a different sort is the green and very spiny fruit of the Jimson weed. Although some plants are still blooming, numerous fruits have been set from earlier flowers that are apparently pollinated by moths. This weedy plant that grows primarily in disturbed soils is famous for its toxins such as atropine and scopolamine which have long been used by humans for medicinal and recreational purposes. However consumption of this plant in the nightshade family is quite dangerous. It is interesting that a variety of hemipterans such as this leaf footed bug feed on the pod and apparently suffer no ill effects. Indeed it is even possible that they may use the toxins in their own defense.
The age and size of young insects can also indicate the season. If caterpillars are in a late stage of growth, the season is usually well advanced. Thus the few caterpillars I see of monarch butterflies at this time of year are in their last instar and ready to pupate. They seem to benefit from the mowing of our hay fields in late June which provides freshly grown leaves during the last half of the summer. I came across this large salt marsh caterpillar, a type of tiger moth which was feeding on ironweed. It is distinctive with its white spiracles along the sides; these are the entry ports for air which is taken into the tracheal system which distributes air directly to the tissues, a radically different method than our lungs.
Dragonflies provide some excellent clues to the approach of fall. I especially watch the behavior of the common green darner which is present everywhere at ponds up until the end of summer, when suddenly it begins to migrate to the south. In its place another large dragonfly appears, the shadow darner, which emerges and takes the niche previously occupied by the green darner. It is apparently much more tolerant of cold temperatures than the green darner. Of course dragonflies are generally creatures of warm days and curtail their activities as temperatures begin to drop.
Cooling temperatures also have a big effect on reptiles and I found this northern water snake basking on a stream-side rock during a cool day. This elevates body temperatures and facilitates growth during times when the prevailing air and stream water temperatures might be too low for much activity. This snake had cloudy eyes (see closeup photo) indicating that it is approaching the shedding of its skin and the warm sun undoubtedly helps to accelerate this process.
The most highly anticipated events of late summer and early fall are the arrivals of migratory birds, especially those such as flocks of bobolinks which stop in our fields and feed and renew their energy stores. The males have lost their breeding plumage and resemble the females. We have planted acres of food and cover for them and enjoy every moment of their visits in the fall and spring. In early evening we often watch the bobolinks and also scan the skies for migrating nighthawks which are also moving south in large numbers in late August and early September. Since we are "snowbirds" ourselves, who will soon migrate to our winter home in Florida, we can understand in some small sense what these birds are going through.
So sharpen your senses this time of year to watch for the signs given by plants and animals of the changing seasons. It is fun and educational to make note of those natural events that occur every year and tell us better than the calendar that times are definitely changing.
Galax, VA & Englewood, FL