IMIS

Here it is published as a standardized Darwin Core Archive and includes for each sampling event an eventID, date, location and sampling protocol (in the event core), the cloudiness, temperature, and wind force at the time of the event (in the measurement or fact extension) and for each occurrence an occurrenceID, the number of recorded individuals, status (present/absent) and scientific name (in the occurrence extension). Issues with the dataset can be reported at https://github.com/inbo/meetnetten-occurrences/issues
Generalized and/or withheld information: as these are sensitive priority species, location information is generalized to 1, 5 or 10 km Universal Transverse Mercator (UTM) grid cells. Original locations are available upon request.
We have released this dataset to the public domain under a Creative Commons Zero waiver. We would appreciate it if you follow the INBO norms for data use (https://www.inbo.be/en/norms-data-use) when using the data. If you have any questions regarding this dataset, don't hesitate to contact us via the contact information provided in the metadata or via opendata@inbo.be.
For all published Meetnetten.be datasets, see https://www.gbif.org/dataset/search?project_id=meetnetten.be
The target butterfly species for Meetnetten.be are listed at https://meetnetten.be/#group-4. Other butterflies observed during the sampling are also included. This dataset covers the site count protocol, for which the target species are Apature iris (purple emperor / grote weerschijnvlinder) and Satyrium ilicis (ilex hairstreak / bruine eikenpage).
Sampling was done using the protocol described in Maes et al. (2019) and explained to volunteers in Ledegen et al. (2018). A site count is similar to a transect in that is it visited multiple times, but unlike a transect it is not divided into different sections. A route is mapped out in such a way that observers pass potentially interesting locations and that it can be walked in about an hour. 1. Apature iris (purple emperor / grote weerschijnvlinder): observation locations are recorded and per route the maximum number of butterflies seen at the same time is noted. Also, for each count, the duration of the search is noted. Three censuses are performed between 10 June and 20 July. 2. Satyrium ilicis (ilex hairstreak / bruine eikenpage): counted along a fixed route, but not divided into sections: butterflies that fly further than 5 m are also counted. Each observed butterfly is recorded. The count takes place three times between the beginning of June and mid-July, at 13 counting areas.