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An End of April Nature Ramble on a VA Farm

 

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That time of spring when the leaves are just starting to emerge is a special period when there is an explosion of flowers on the forest floor. The usual explanation for this burst of growth is that the increased light due to the lack of leaves permits such exuberant biodiversity of small plants. Once the canopy closes, the amount of light becomes a severe limitation for the growth of plants and only shade tolerant species can survive and grow. An iconic plant of this time is the May apple which is shown here in dense stands next to a deer exclosure fence which I have built to determine the effect of excluding deer from an area of forest floor. May apples and bloodroot are quite poisonous and do not seem to be affected by herbivory, but some species such as trilliums are greatly impacted. The large flowered bellwort seems to thrive in the forest despite an over-abundance of deer. The tall butterwort is very numerous in sunny areas which have been grazed or mowed since it does not compete well with grasses, but is apparently toxic to herbivores. The spectacular birdfoot violet shown here was growing in a dry hard path and I have not seen it previously. 

One of the most unusual insects you may encounter is the luna moth which I found on the edge of a forest path. I am assuming this is a male due to the large branched antennae which are likely used to detect pheromones released by females. The green color of this moth could be considered camouflage, but it also has four "eye" spots which may serve to deter predators which do find the moth. The purplish edges of the wings are only found in southern populations that emerge in spring; summer moths have yellowish edges. The reason for this is unclear but may represent a genetic difference between broods in different seasons. It is hard to fully comprehend the evolutionary significance of the overall spectacular shape and appearance of this moth, but it is certainly a joy to encounter one. 

Amphibians are quite active in spring, especially those species that breed in ephemeral ponds. Although I missed the actual breeding, I found groups of black wood frog tadpoles in our ponds. They keep together in the shallows where it is much warmer and they can grow faster. Toads have been singing their long trillls and there is a great deal of competition among males for females. In this trio of males, one is calling (notice the expanded throat of the darkest toad) and the other two males are attempting to mount each other. Males reject such unwanted advances with a special chirping call and vibrating. Green and bullfrogs are not yet breeding but are found sunning themselves. This large female green frog illustrates how you can distinguish green frogs from bullfrogs; green frogs have a more pointed snout and also have a fold of skin that extends from the eye backwards along the body. 

Of course birds are extremely active in late April and many species are still in migration. For those that have reached their summer homes, they are actively beginning to breed. Males of many species are in their breeding plumage which can be gorgeous. Every year we have at least one pair of wood ducks that checks out our ponds which are quite suitable, except that these ducks have been hunted so much that they do not accept any human presence. The female wood duck is quite well camouflaged, which is not likely an adaptation for nesting which is done in a cavity hidden from sight, but probably protects the hatchlings, which leave the nest immediately and follow the female, from discovery by predators. The male is an amazing display of bright colors which presumably advertise his vigor and ability to sire healthy offspring. When we see such a bizarre plumage we can only conclude that the females are choosing their mates based on the brightest colors. 

Tree swallows are breeding in many of the nest boxes that we place on poles for them and bluebirds. Here again the female is dull in color and nests in a cavity and the male is bright blue/green. The color of the male varies depending on the direction of the light. This shows that the origin of the color is not a pigment but refracted light rather like a prism. We enjoy the frenzied activity of the swallows even more since we consider them old friends that we also encounter in Florida during the winter. There they join in enormous flocks and feed in large part on berries of the wax myrtle. 

Every day in spring brings new sights and new wonders. If you are a naturalist it is impossible to be bored this time of year. 

Bill Dunson 
Englewood, FL, and Galax, VA 

wdunson@comcast.net 

http://www.galaxgazette.com/blogs 

http://lemonbayconservancy.org/dunson_archives.htm 

http://lemonbayconservancy.org/wildflower.htm