Questions Posed upon Point Objects

Whenever a wildlife study is being performed, the research goals can be classified into approximately seven questions. They reflect to some extent the evolution of the discipline.

• What is it? Due to a lack of binoculars, the first ornithologists were using a gun to be able to identify their 'observations', a common task in the high times of taxonomy.
• How many are there? This question is at the core of biologists. While most humans can simply enjoy watching animals, biologist can nothelp themselves start counting them.
• Where is it? After the two basic questions the focus is shifted to spatial aspects. The distribution of species became a large field of research.
• Why is it there? In the middle of the 20th century the whole complex of habitat analysis became popular.
• How does it influence others? Along with the developments of 'niche theory' and competition the whole ecological questions about how animals interact with their environment became a big research issue.
• Does it change? Due to the confrontation with progressing environmental disturbance and devastation the temporal aspects became more and more prominent in the questions of wildlife research.
• Where will it go?

Today's main focus in research and methodological developments lies in the last three questions. It is still very difficult to adequately characterize changes in wildlife data, and extrapolations into the future are even more difficult. The general topics mentioned in the above list need to be broken up into smaller questions to be operationalized. Table 2.4 provides a list of more detailed questions. It also includes a classification whether the questions include spatial and/or temporal aspects.

Table 2.4: List of example questions often posed in wildlife research when studying a certain species.

Spatial	Temporal	Question
		How many animals are there?
	t	Is there a change in the number of animals (increase, decrease)?
	t	How much does the number of animals fluctuate ($\sigma$, $\sigma^{2}$, stderr etc.)?
s		What is the density of animals?
s		Are there density differences between subareas?
s		Are there density clines (trends)?
s	t	Is there a change in density (measurements) over time?
s		Where are the animals?
s		How can I describe the distribution?
s		Does an animal always use the same paths?
s	t	Does it occur multiple times at the same place?
s		Which locations are important for an animal?
s		Which locations are used more intense than others?
s		Which locations are used less intense than others?
s		Where are corridors used by animals?
s	t	At which daytimes are certain areas used?
s	t	In which seasons are certain areas used?
s		Are the animals distributed in a randomly, aggregated (clustered) or evenly manner?
s	t	Is there a change in the distribution pattern over time?
s	t	Is there a positional shift over time?
s	t	Is there a dispersion change over time?
s	t	Is there a change in intensity of aggregation?
s		Are there minimal distances between points?
s		Is there a difference between 2 samples?
s		Is there a positional shift between the 2 (n) samples?
s		Is there a difference in dispersion between the 2 (n) samples?
s		Is there a difference in clustering between the 2 (n) samples?
s	t	Is there an influence of the moon or sun on the spatial distribution of the animals?
s		Is the distribution random according to other objects (points, lines, polygonal features)?
s	t	Are there distinct phases in which there is little change, which can be defined for further analysis?
s		What are the environmental parameters influencing (determining) the distribution of the animals?
s		What is the influence of a specific environmental parameter on the distribution of the animals?
s		Are there environmental parameter clines which could explain clines in the animal data?
s		What habitat is available to an animal?
s		How big is the area an animal is using (homerange)?
s	t	How does the size of a homerange change over time?
s		Are there barriers in the dispersion of animals?
s		What is the mean distance between objects?

It is worth noting that almost all questions listed in table 2.4 include spatial aspects. About one third have temporal aspects. Of course the list is by far not complete, but the strong need for methods dealing with spatial and temporal aspects becomes evident.

In the following chapters I will try to give an overview of analysis methods that are available today. I will concentrate on methods dealing with point objects as the intention for this work stems from the work with wildlife data.