Nature in the Blue Ridge as Summer Comes to a Close

August 30, 2017

Nature Notes by Bill Dunson

During the past few weeks in August I have been centered in the Blue Ridge mountains near Boone, NC but have sallied out to Galax, VA, and briefly down to the Piedmont in Gastonia, NC. The nights have been getting cooler (down to 55 F once) but the days are still sunny and warm. Most plants have bloomed and are setting seeds and fruit. Some birds have migrated and most are hardly to be heard anymore. There is a frenzy of insect activity on the remaining flowers.

One of the most spectacular flowers of summer is the water lily. It is not only beautiful but is now thought to resemble the earliest type of flowering plant. It is usually pollinated by beetles, which is a primitive trait since pollinating bees and butterflies are more recent evolutionary groups.
http://www.independent.co.uk/news/science/first-ever-flower-found-scientists-angiosperm-water-lily-fossil-nature-communications-a7872776.html

If you walk by a pond you will notice a lot of activity among the dragonflies. The autumn meadowlhawk is a species that emerges late in the season whereas the blue dasher (male shown here) occurs throughout the summer. Although primitive, dragonflies have complex behaviors and you can observe males fighting for territory and females, and guarding females while they lay eggs. In both of these species the males are much brighter in coloration than the females (sexual dimorphism), which indicates that the females choose which males to mate with. More striking colors may cue the female as to which males are more virile/viable.

One of the striking flowers of late summer which many dislike is the thistle, a giant weed with thorns. However it is highly favored as a butterfly plant and you will notice here a great spangled fritillary drinking nectar from a pink thistle. I used to devote some effort to cutting their seed heads off but eventually found that they are typically found only in disturbed soil and will gradually diminish with succession if you protect the soil from physical disturbance.

Bumblebees are quite active in late summer and early fall since they can maintain a body temperature higher than the environment by muscular contractions. They show what appears to be intelligence in forging for nectar when they bite the base of flowers such as these black and blue salvia to obtain the sweet fluid, which they cannot reach with their tongue down the narrow flower corolla tube. Although they are a large and well protected bee they can be preyed upon by the remarkable robber fly. This predaceous fly had captured a much larger bumblebee and was in the process of eating it when I noticed the battle underway on a garden path.

This bullfrog female (note the ear drum is smaller than the eye) was sunning in a protected spot along a small creek. The male has a much larger ear drum which presumably assists in detecting the famous jug-o-rum calls that are exchanged between males and are involved in territorial disputes.

As the weather becomes cooler, turtles are seen basking more often along logs and rocks. This thermoregulation is useful in increasing metabolism of these reptiles that lack an internal metabolic means of heat generation. The warmth and drying also likely improve the health of their skin. These red-eared turtles in a pond in Gastonia are actually the result of babies that were kept as pets and released and thrived in local ponds. They are an invasive species in many places throughout the world.

One of the common aquatic mammals that you may not often see is this muskrat which I noticed as it swam under a bridge. They are interesting as a specialized semi-aquatic mammal which feeds on herbaceous plants instead of the tree bark and shoots eaten by beavers. They have a flattened but narrow tail and webbed feet. The yellow flowers on the right are green headed cone flowers which are composites near their peak of flowering in late summer.

Enjoy the last hot days of summer since they will soon enough disappear. Already I have noticed that red leaves of black gum are falling, notifying us of the coming frosts.

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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