1999 Volume 39 Issue 3-4 Pages 140-147
The population structure of the damselfly, Calopteryx atrata was studied in a small stream surrounded by hills in Shiroyama, Kanagawa Pref. in 1993, using a mark and recapture method. The distribution range of individuals was limited within 800m along the stream, where water flows slowly. Males had a wider distribution than females both in the upper and lower directions of the stream. As for the movement along the stream males did not have clear tendency, but females showed the tendency to go upstream with time.
Based on the estimated number of individuals using the Jolly’s Method, the reliability of the estimation by the Lincoln’s Method was examined. When the interval of survey was long (e.g., 4 days or 7 days), the value calculated by the Lincoln’s Method was excessively large. This might be because the Lincoln’s Method left the death of individuals out of consideration. On the other hand, when the survey duration was short such as one day, little difference was found between these two methods. These suggest that a reliable value can be obtained by the Lincoln’s Method when we have less influence of the actual death of individuals by shortening the survey interval. As junior and high school students can easily make the calculation in the Lincoln’s Method, the introduction of this method into biology education will be appreciated.
