IMIS

The occurrences are georeferenced using the centroid of their respective 5 x 5 km² Universal Transverse Mercator (UTM) grid cell and are derived from the database Vlinderdatabank at the INBO, which consists of (historical) collection and literature data (1830-2001), for which all butterfly specimens in institutional and available personal collections were digitized and all entomological and other relevant publications were checked for butterfly distribution data. It also contains observations and monitoring data for the period 1991-2014. The latter type were collected by a (small) butterfly monitoring network where butterflies were recorded using a standardized protocol. Together with the dataset Vanreusel et al., the dataset represents the most complete overview of butterflies in Flanders and the Brussels Capital Region (north Belgium).
Geographic coverage: Flanders and the Brussels Capital Region. These regions cover an area of 13,522 km² and 162 km² respectively (13,684 km² in total). This area is situated in the northern of Belgium and represents 45% of the Belgian territory. Flanders is largely covered by agricultural land and urban areas while the Brussels Capital Region is mainly urban. All occurrence data were recorded or are generalized to grid cells of 5 x 5 km² of the Universal Transverse Mercator (UTM) coordinate system, with the grid codes indicated in the field verbatimCoordinates. The WGS84 centroids of these grid cells are calculated in decimalLatitude/Longitude with a coordinateUncertaintyInMeters of 3,769 meters using Wieczorek et al. 2004.
Taxonomic coverage: The dataset covers all 67 indigenous and 3 regular migrant butterfly species (Colias croceus, C. hyale, Vanessa cardui, V. atalanta). Vagrant or doubtful species (Apatura ilia, Arethusana arethusa, Boloria dia, Brenthis ino, Coenonympha arcania, Colias alfacariensis, C. palaeno, Cupido argiades, Danaus plexippus, Erebia aethiops, E. ligea, E. medusa, Hamearis lucina, Iphiclides podalirius, Lampides boeticus, Lasiommata maera, Limenitis populi, L. reducta, Lycaena dispar, L. helle, L. hippothoe, L. virgaureae, Melitaea aurelia, Pontia daplidice) and introduced species (Cacyreus marshalli and Polyommatus damon) were excluded because no evidence of the observation was available.
Sampling methods: Butterfly distribution data were collected in four different ways: i) collection data, ii) literature data, iii) monitoring transect data and iv) observations. - Collection data were digitised from the following museum collections: Bosmuseum Groenendaal, Royal Institute for Natural Sciences (Brussels), Agricultural Faculty of Gembloux, Ghent university and the Antwerp Zoo. Furthermore, the private butterfly collections of the following people were also incorporated into the INBO dataset: A. Artoisenet, R. Bracke, A. Caljon, S. Cuvelier, A. De Boer, K. Desender, P. Halflants, D. Hilven, J. & T. Jaeken, M. Keirens, H. Kinders, P. & W. Pardon, W. Tips, W. Troukens, F. Turelinckx, O. Van De Kerckhove, R. Van Heuverswijn, B. Vandepitte, J. Vervaeke & R. Winnen. The source collection is indicated in the field associatedReferences. - Published observations were searched for in different literature sources and indicated in the field associatedReferences. Since most of the records in collections and in the literature were only reported at the municipality level, the UTM 5 x 5 km² UTM grid cell of the centre of the municipality was attributed to the record. - Butterfly monitoring counts were conducted along fixed transects of maximum 1 km, consisting of smaller sections, each with a homogeneous habitat (e.g., woodland, hay meadow, dry heathland – see van Swaay et al. 2008; van Swaay et al. 2011 for a detailed description of the monitoring method). - Observations (species, date, location, observer) were recorded by volunteers/citizen scientists (mainly for the period 1991-2007, usually with a resolution of 1 x 1 km² or 5 x 5 km²).
Quality control: All data were carefully verified by butterfly experts (including professional entomologists). The validation status is indicated in the field identificationVerificationStatus.
The publication of this dataset was supported by the INBO as part of the Flemish contribution to LifeWatch.