BACKROUND INFORMATION	HOME	STUDY SITE	TEMPERATURE	HUMIDITY	WORKS CITED

            We predicted that the highway pavement will produce the highest temperatures and the greatest fluctuation in soil humidity.  The high temperatures are a result of the surface material, pavement.  The pavement absorbs the heat from the sun and this energy is transferred into the nearby soil, raising the soil temperature.  The high temperature will result in a large percentage of all-female nests or nests that are biased toward the female sex (Janzen 1593).  Along with the temperature, the surface material will also cause a large amount of variation in the soilmoisture.  On hot, sunny days the heat will be amplified by the pavement.  This will cause the soil to desiccate.  Conversely, on wet, rainy days the pavement will not absorb the precipitation and the water will run off onto the shoulder of the road, elevating the soil moisture.  Consequently, the size of the eggs and hatchlings and the length of incubation will be dependent on the precipitation.  We believe that this fluctuation in humidity will adversely affect the development of the eggs.  This is because the eggs rely on passive processes to absorb moisture from the soil surrounding them.  The constant change in the soil humidity will cause an equal amount of variation in the mass of the egg.  The instability of the egg mass could cause the embryo’s mass to change as well.  Constant weight gain and loss may adversely affect the development of the hatchlings.  Ultimately, this could result in small, lethargic hatchlings that have a short incubation time.
            We hypothesized that the wooden fence will cause the soil to have the highest humidity and lowest temperature.  The design of the fence creates a large shadow.  By blocking the sun, the wooden fence causes the soil to cool.  The lower temperature will produce a larger number of all-male nests and nests with more male hatchings (Janzen 1993).  The wooden fence also absorbs and retains a larger amount of water.  The water in the fence may soak down the fence and into the soil.  This will raise the humidity in the soil.  The elevated humidity levels will produce larger hatchlings and a larger percentage will live to sexual maturity.

 

            The metal fence is precictedto produce dry, warm soil.  Because the fence provides little or no shade, the soil’s temperature is determined by the sun and the amount of vegetation in the area.  Because of the lack of shade, the area around the metal fence will yield higher soil temperatures then the wooden fence.  However, the metal fence will have a lower temperature then the roadway because there is no pavement or other surface material to absorb the sun’s energy.  We believe this will result in the most variation in the gender distribution of the hatchlings.  The humidity by the metal fence will be relatively constant.  The soil will naturally retain some water from rainfall but, because there is nothing to artificially enhance the amount of water retention, the humidity will not be as high as the wooden fence.  Depending on the amount of rainfall, this may result in shorter incubation times and smaller hatchlings.