An October Farewell to the Blue Ridge

October 17, 2014

Nature Notes by Bill Dunson

It is time for our annual migration to Florida so we are bidding a fond farewell to our beloved Virginia Blue Ridge mountain farm. During the brief interludes in rain over the past week I have been able to catch some typical fall views of this area. Of course the overwhelming impression one gets now is of the beautiful fall leaf colors. One of my favorites is the sourwood, a small forest sub-canopy tree in the heath family that has an amazing combination of red and yellow leaves and sprays of dry whitish fruits. The leaves actually have a sour taste as the name implies. Our rusty blackhaws, a viburnum, are covered in fruits, many of which surprisingly are not yet ripe. Note that of this cluster of 11 fruits, two are black/ripe, four are reddish and approaching ripeness, and five are greenish and far from ripening. The use of color to signal birds when fruit is ripe and edible, and the seeds are ready for dispersal, is very interesting since it allows a plant to maximize its seed production. The process of sequential rather than simultaneous ripening of a group of fruits may also reflect the efficiency of seed dispersal, so that one bird eats only a few and then another bird comes that is going in another direction and eats another.

You normally think that fall is a time when insects decrease in numbers and then disappear when frost occurs. That is generally true but this beautiful male autumn or yellow-legged meadowhawk is one of the few dragonflies that is characteristic of fall. It is the latest dragonfly to emerge from its aquatic larval phase and one of the latest breeders. This essentially allows cold-tolerant species to occupy a distinct niche. The meadowhawk was present with shadow darners and great spreadwing damselflies around one of my fish-less ponds. The damsels were in tandem and thus breeding. One damselfly, which is a predator on other insects, encountered another larger predator, the barred garden spider, and became a meal. The food web here was literally the spider web of death!

I also encountered a very large gravid female praying mantis which will soon be laying a capsule that will protect the eggs though the winter. In most cases the adults die during the winter and continuation of the species is due entirely to the eggs. This is likely a Chinese mantis, introduced to the US for insect control. The problem is that the mantis does not limit its predation to noxious insects but eats beneficial ones as well.

Reptiles are not seen often during the fall as temperatures drop. This garter snake seemed to be warming itself in a sunny opening in the forest. I picked it up to admire its colors but you may be unaware that garter snakes actually are mildly venomous! They have enlarged rear teeth and can chew and deliver a mild neurotoxic venom from the Duvernoy’s gland. It would be harmless to most people unless you were allergic to the secretion.

There is a lot of bird activity in fall with migrants passing through. This female northern flicker was hard at work digging in an old stump looking for insects. Although flickers occur throughout the eastern US all year, birds in your yard may not be the same individuals in summer and winter. Canadian flickers may move south into your area and your flickers may move south.

There is much natural history to enjoy in fall but prepare yourself for the approaching winter and the huge changes to come.

Bill Dunson

About Bill Dunson

Bill Dunson, born in rural Georgia, skipped 12th grade and went directly to Yale. Bill subsequent-ly received a PhD in Zoology from the University of Michigan, studying softshell turtles. Bill is Professor Emeritus of Pennsylvania State University thanks to a career spent entirely at that institution, teaching and doing research on the physio-logical ecology and ecotoxiciology of reptiles, amphibians and fish. Always curious about nature, Bill has dedicated his life to learning and sharing his knowledge with others. He has served on many advisory boards here in Southwest Florida to preserve the water that gives life to our region.

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