1. Species status assessment and monitoring in the Belgian continental region: general options & examples from insects
Philippe Goffart & Marc Dufrêne
(Ministère de la Région wallonne / CRNFB)

2. Introduction
Context
The assessment of species status is required every six years within the context of the Habitat Directive and the Natura 2000 network
Needs
It implies the development of :
appropriate monitoring schemes
adapted and reliable method to estimate trends

3. General options Range mapping
Data selected within one of three windows periods according to the completeness of the data
so as to fit to the rhythm of 6 years for the reporting:
(6 years) first choice, if possible
(12 years) next choice
(18 years) last choice, if poor sampling

4. General options Trends analysis General monitoring
Comparison of data from two six year periods, if possible
Otherwise, expert judgement
General monitoring
Minimum required:
visit to the known localities...
...at the right time of the year…
...once every six years
all of them if < 60 localities
80% of them if localities
70% of them if localities
60% of them if > 120 localities

5. Trends analysis Development of a new method Principles
To estimate changes in:
range size
observation rate per visit
…between two six years periods of a survey or a monitoring scheme.
Comparison achieved on grid cells visited at the right time at both periods (to neutralize the spatio-temporal heterogeneity of sampling).

6. Results for butterflies
Table 1. Trend analysis with classical and new methods of comparisons for three N2000 butterfly species (G test for goodness of fit).

7. Specific monitoring schemes
Designed for some species with restricted range and fluctuant (meta)populations
Example: Marsh Fritillary
(Euphydryas aurinia)
Monitoring by counts of caterpillar nests at the end of summer in main colonies (13 years)

8. Marsh Fritillary (Euphydryas aurinia)
Range rather stable between the two
6-year periods (Δ% = 0%)...
But strong fluctuations within individual colonies and important decline during the last two seasons
Example of two populations

9. Other species ...
similar approach when data available are or expert judgment
many problems for mammal species (bats and others species from Annex 4 and 5) that are indeed not well known. Only beaver is well monitored.