A Mid-October Nature Ramble

   Although mid-October weather is beginning to reveal signs of the winter to come, there is still much interesting natural history to observe in the multi-colored woods.  Spiders become more obvious as leaves fall.  I noticed a female fishing spider carrying her egg sac in her jaws next to a pond where she hunts for aquatic and semi-aquatic prey.  She carries the eggs around until they hatch and then she constructs a nursery web for protection of her babies.  Isn't it interesting how this "primitive" species shows such a strong maternal instinct.  As humans we need to realize that some of our most revered traits (maternal care) are really evolutionary mandates (the selfish gene) that originated quite early in the history of life on earth.



Although it is common to hear insects singing it is not so easy to find them, such as this angle wing katydid that is so well camouflaged.  Not only does the green color blend in with leaves but the wing structure mimics leaf venation.  This is a female as revealed by the ovipositor.  The realism of such leaf mimicry reveals how intense the scrutiny of birds must be for insect prey and how the "arms race" between predator and prey must be responsible for such remarkable camouflage.  


One insect that is easy to find in fall is the woolly bear caterpillar which is the larval stage of the Isabella tiger moth.  The caterpillars overwinter and a myth has arisen about the relation between the severity of winters and the width of the light band.  At any given time you will find caterpillars with bands of varying widths and the width increases with the age of the caterpillar.  Despite this failure as a weather prophet, the caterpillars are charming to children and adults; it is nice to be able to pick up a caterpillar and not be stung.


As the seeds of many plants mature, seed-eating birds such as the goldfinch enjoy the bounty.  This female in non-breeding plumage is feeding on the seeds of the Maximilian sunflower which we have planted in some of our fields to replace exotic cold-season pasture grasses such as fescue.  Goldfinches have a smaller bill than the indigo bunting and blue grosbeak which live in similar habitats. Their ability to feed on smaller seeds than these and other competitors could be considered an example of competitive displacement of bill size, for which the Galapagos finches are so famous.


Directly over our sunflower fields I recently saw a bald eagle soaring up in a spiral within a rising thermal air current.  Eagles are impressive birds and this juvenile (basic 1 stage about 8 months old) may have flown north from its nest site in Florida.  The age/stage of bald eagles is most easily judged by looking at the trailing edges of the wings (the secondary feathers are pointed in juveniles but the adjacent edges become smoother in the next molt).  Although bald eagles are common breeders now in FL, I never fail to be thrilled by observing them, especially up north where they are generally much less frequent.  


Bill Dunson, Englewood, FL, and Galax, VA