Example Application: Moon illumination and Badgers

Even though the dynamics is essential in the analysis of temporal data, the following paragraphs will try to present a simple analysis of this type on the static medium paper.

The animal species used in this example is the Badger Meles meles. They are nocturnal animals that can feed on a variety of food. They are known to feed in forested as well as agricultural areas. A study on the spatial behavior of badgers is conducted in the Sihlwald area by Karin Hindenlang (Zool. Instit., University of Zurich), using radio telemetry to locate the animals. As in many studies on wild animals there are questions about the influence of the moon on the spatial behavior of the badger. Due to a lack of efficient methods for analyzing such cyclic temporal aspects, lunar influences, however, have seldom been verified.

The sample data were analyzed for this purpose to see whether there is an influence in the spatial behavior in one of the badgers followed by telemetric means. As stated above I will only provide a static representation of the findings. In figure 4.9 the data were divided into two phases. In the left map all localizations of the badger during the full moon phases are plotted. The median center was calculated and a so called star or spider plot was produced. It shows clearly that all observations with one exception were located within the forest. In contrast to that the locations made during the new moon phase show a completely different picture (figure 4.9 right). The median center of the observations lies very close to the forest border and a majority of them was made outside of the forest in the meadows adjacent to the forest.

Figure 4.9: Radio locations of one badger in the Sihlwald in September 1996 (Data by K.Hindenlang). Left: full moon phase. Right: new moon phase. Red: star plot from the median center with the observations. A red line is drawn from the median center to each observation. Green = forest. Blue = Sihl river.

A more detailed analysis showed that the shift from the inner parts of the forest to the forest edge occurred in times from about one third (moon illumination 30 percent) before new moon to about one third after new moon, resulting in about one third of the time as meadow oriented and about two thirds of the time as forest oriented activity.

Using the prototype application TUPF, this kind of analysis took only a few minutes to be performed. Normally this would not even have been conducted. It would have taken a lot of work depending on the sample size and its spatial distribution. Neither the ideas and concepts nor the software for such analysis were available. This little example shows the power of the concept of temporal data frames.

The above data were used for demonstration purposes. The reader is reminded to be careful not to draw false conclusions from the illustration above. The sample dataset I received for this testing analysis was relatively small. To confirm whether there is really such an influence of the moon on this badger's spatial activity, a larger volume of data needs to be analyzed. This will be done as soon as the data are available according to the advances of the badger study.

In Appendix A movie examples for the temporal data frames are provided. They are video-shots of the prototype application TUPF. They shall serve as intermediate illustrations between the static (paper) and the fully interactive (TUPF) descriptions of the concept.