Example Habitat Model of Lesser Spotted Eagle

The lesser spotted eagle is one of the key species in northeast Germany. To improve understanding of the fuzzy modeling technique, a simplified fuzzy model using the lesser spotted eagle will be explained. (The real model discriminates more details in the habitat structure, but this is not important for understanding.)

Habitat structure

The habitat structure of any animal depends on nutrition, the possibility of reproduction, and protection against predators and other dangers. For the lesser spotted eagle this means that:

• When hunting, it can either be flying or sitting and waiting. If it hunts in flight, plant cover must not be too dense, so that it can see the prey on the ground. To enable it to sit and wait some 'structure elements' to perch on must be available.

• The lesser spotted eagle breeds in a forest. It must be able to reach the hunting area from the nesting place.

• There are no predators in the region, but wind energy plants or roads and railways might be dangerous too.

Fuzzy model nutrition

The investigated area is located northeast of Berlin, and measures approximately 18 km x 30 km. Most of the area is used for agriculture but there are also grasslands, forests, lakes, and settlements.

Before the fuzzy model 'nutrition.fis' can be used the coverage of the soil with plants must be calculated. The coverage depends on the type of crops and therefore on the time of year. The crops covering the soil are shown in Figure 4. As an example the year 1995 and the year day 160 was selected.

Another input for the nutrition part of the habitat model for the lesser spotted eagle is the structure density

Figure 4 Degree of crop cover. White areas - non-food area; gray color - the brighter the color the smaller the coverage degree (the white areas are lakes, forest, and settlements).
Figure 5 Mean distance to structure elements; the darker the color the smaller the distance.

map (in this map the mean distance to structure is shown). A high density of structure can partly compensate a high cover of crop degree because the bird is able to use a structure element (hedge, tree, etc.) as hunting point. This input is represented in Figure 5.

Remark This map was produced using moving window technology to generalize from the real structure to a more characteristic landscape.

The output is calculated using a fuzzy model. The two fuzzy inputs, degree of coverage and structure density, are shown in the following:

Coverage degree [0.000..1.000]

Very small

-0.100

0.000

0.100

0.200

Small

0.100

0.200

0.300

0.400

Medium

0.300

0.400

0.600

0.750

High

0.600

0.750

1.000

1.100

Mean distance to structure [ 0..1000]

High

-0.1

0

100

200

Medium

100

200

250

300

Small

250

300

1000

1001

Crisp values were used as outputs:

Very

Small

Medium

Medium

Medium

High

Very

small

0.2

small

0.5

high

0.8

high

0

0.4

0.6

1

The rule base is very simple. It

can be presented as

follows:

Coverage

degree

Structure

Output

Numoutput Weight

Very small

High

Very high

1 1

Very small

Medium

Very high

1 1

Very small

Small

High

0.8 1

Small

High

Very high

11

Small

Medium

Medium

0.6 1

high

Small

Small

Medium

0.5 1

Medium

High

Medium

0.6 1

small

Medium

Medium

Medium

0.4 1

small

Medium

Small

Small

0.2 1

High

High

Medium

0.4 1

small

High

Medium

Small

0.2 1

High

Small

Very

0 1

model it is easy to estimate the influence of planned wind energy plants or of some alternative land use modes. The model can be used to optimize the location for new wind energy plants. The big advantage of this modeling approach is that all influences for the habitat quality will be considered. It is not logical to protect the lesser spotted eagle in a region where it cannot live.

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