Blue Ridge Ramble in Late July

September 10, 2011

Nature Notes by Bill Dunson

One of the major features of the natural history of summer is the progression of breeding in which some species breed once and then stop at various times of the summer, and some reproduce all of most of the summer. It is a great pleasure to observe this sequence of the rejuvenation of life. The fun is in finding “old friends” that you know well from previous years, or in occasionally encountering something new. Thus I was surprised to find a plant in fruit which I did not recognize on a south-facing forested hillside with rich soil. After some page turning in plant guides and some web searching I discovered that this was a goldenseal with fruit (see photo). Now goldenseal or orangeroot is a buttercup-relative which is a famous and valuable plant since it has a long history of medicinal use by humans.

In contrast a very common plant which I found of interest is the black-eyed Susan, a coneflower which we have planted in large numbers in fields along with other wildflowers to replace exotic pasture grasses. This particular flower (see photo) is a color variant in which a reddish brown pigment encircles the inner part of the petals. But I was particularly interested in watching the progression of blooming in the disc flowers which make up the “cone” of this composite/aster family “flower.” This family is one of the most highly evolved in producing a reproductive “flower” that is actually made up of many smaller flowers specialized to make petals or to reproduce (disc flowers). In this photo you can observe the tiny yellow disc flowers blooming in a circular pattern which will gradually progress to the top of the cone. So we can observe a remarkable process occurring even in something so common.

Nearby on a black-eyed Susan there was a common buckeye butterfly perched with its wings open, allowing us to observe the interesting pattern on the inside of the wings. The so-called eye-spots are believed to either scare away bird predators, or divert their attacks to peripheral areas of the wing which are less vulnerable than the body. In fact you will note that there are three separate holes in the edges of the hind wings which are likely peck marks made by birds.

An insect that is usually heard rather than seen is the annual or summer cicada (see photo). The buzzing call of the males is a characteristic sound of summer that we rarely give any thought to.
The “annual” cicadas actually require 3 to 5 years to mature from a subterranean nymph, but this is far less than the periodical cicadas that remain underground for 13 to 17 years. I am enthusiastic about the sounds of nature, not only because they allow us to identify many creatures that are only rarely seen, but they add an extra level of interest and complexity to the tapestry of life.

One of the most distinctive sounds of summer is the jug-of-rum call of the male bullfrog which is defending its territory and attracting females with this vocal display. Our bullfrogs call every night and I found some eggs just last week (see photo of embryos). Bullfrog eggs are laid in a matrix of thin jelly that floats as a film on the surface, quite unlike the globular clusters of woodfrogs or leopard frogs. This is likely related to the differences in temperature of the water at the time of breeding and the smaller amounts of oxygen present in warmer water. So why is it that male bullfrogs have a huge eardrum (see photo) much larger than that of the females? This seems to be due to the importance of sound in defense of the pond-edge territory. But females are also known to rely heavily on sound to judge the body size and thereby the quality of the territory of the mate they choose. So when you listen to bullfrogs, see if you can discern the big boys with the deeper voices.

Mourning doves are one of the species that breed almost continually and it is interesting to watch their nests. Their nest is minimal but obviously adequate for the purpose and they normally lay only two white eggs which would be extremely obvious to predators if the adult were not covering them. However one advantage of the tiny nest is that when the parents are away, the nest is not easily visible and the babies are rather cryptic in color (see photo). Indeed this nest on a fence post is rather open, yet the babies are quite inconspicuous. These nests are usually discovered only when the adult flushes.

So see if you can hone your listening skills this summer and tune into the extravagant sounds made by insects, amphibians, birds and mammals. Another benefit of listening to creature sounds is that you can often observe and study while being lazy!

Bill Dunson, Englewood, FL & Galax, VA

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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