Meetnet Agrarische Soorten - Monitoring of birds and mammals in agricultural areas in Flanders, Belgium

Sampling event Observation
Latest version published by Research Institute for Nature and Forest (INBO) on Feb 2, 2026 Research Institute for Nature and Forest (INBO)
Home:
https://www.vlaanderen.be/inbo/meetnet-biodiversiteit-in-het-agrarisch-gebied-mbag/wat-is-mbag/
Publication date:
2 February 2026
License:
CC0 1.0

Download the latest version of this resource data as a Darwin Core Archive (DwC-A) or the resource metadata as EML or RTF:

Data as a DwC-A file download 261,380 records in English (15 MB) - Update frequency: as needed
Metadata as an EML file download in English (24 KB)
Metadata as an RTF file download in English (19 KB)

Description

‘Meetnet Agrarische Soorten - Monitoring of birds and mammals in agricultural areas in Flanders, Belgium’ is a sampling events dataset published by the Research Institute of Nature and Forest (INBO). Meetnet Agrarische Soorten (MAS) is a monitoring scheme focused on farmland biodiversity in Flanders (northern Belgium). It is part of the MBAG project (“Meetnet Biodiversiteit in het Agrarisch Gebied”). The MAS uses a stratified random sampling design to monitor population trends and to investigate the effectiveness of biodiversity conservation measures for breeding farmland birds and mammals across six agricultural regions. This dataset contributes to long-term biodiversity monitoring and provides policy-relevant indicators for the conservation of farmland species in Europe.Data are collected by trained volunteers and professionals following a harmonised field protocol. At each sampling point, all individuals of target species observed within a 300-meter radius are recorded with an associated breeding code. Each point is surveyed four times per breeding season, within fixed time windows.The dataset includes occurrence records from 2018 onward, with annual updates planned. In addition to the standard monitoring data, the dataset also contains extra records that did not strictly follow the MAS protocol. They are not part of the official stratified monitoring sample, for example observations outside the 300-meter radius or outside the designated time periods. Such observations are indicated by the occurrenceRemarks field. Species names are standardised against the GBIF Backbone Taxonomy. Data cleaning, processing, and Darwin Core mapping are performed using reproducible R-based workflows.This dataset is published as a standardised Darwin Core Archive (DwC-A) with an Event core and Occurrence extension. This DwC-A includes for each sampling event an eventID, parentEventID, date, location, sampling effort and sampling protocol (in the event core) and for each occurrence an occurrenceID, the number of observed individuals/pairs/territoria/nests, behavior, status (present/absent), life stage, scientific name and Dutch vernacular name, plus observer and identification fields (in the occurrence extension). The field occurrenceRemarks is used as a controlled flag: "mas_protocol_sample" for observations at MAS sample locations that strictly follow the MAS protocol, and "mas_additional_sample" for protocol-incompatible observations outside the 300 m radius and/or outside the designated counting periods. All the occurrences per count (on a specific day and counting point) are grouped by a parentEventID.Generalised and/or withheld information: as this dataset includes sensitive data, nest location information is generalised to 5x5 km Universal Transverse Mercator (UTM) grid cells, systematically for four critical priority bird species (after withholding their nest records during the first two years), and only during two years for all other species. Besides, observations of regionally threatened mammal species are also generalised to 5x5 km UTM.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 the data management plan of the MAS project, see Eves Down et al. (2025).

Data Records

The data in this sampling event resource has been published as a Darwin Core Archive (DwC-A), which is a standardized format for sharing biodiversity data as a set of one or more data tables. The core data table contains 261,380 records.

1 extension data tables also exist. An extension record supplies extra information about a core record. The number of records in each extension data table is illustrated below.

Event (core)
261380
Occurrence 
264130

This IPT archives the data and thus serves as the data repository. The data and resource metadata are available for download in the downloads section. The versions table lists other versions of the resource that have been made publicly available and allows tracking changes made to the resource over time.

Versions

The table below shows only published versions of the resource that are publicly accessible.

How to cite

Researchers should cite this work as follows:

Langeraert W, Van Calster H, Cooleman S, Eves Down M, Jansen J (2026). Meetnet Agrarische Soorten - Monitoring of birds and mammals in agricultural areas in Flanders, Belgium. Version 1.2. Research Institute for Nature and Forest (INBO). Samplingevent dataset. https://ipt.inbo.be/resource?r=meetnet-agrarische-soorten-vlaanderen&v=1.2

Rights

Researchers should respect the following rights statement:

The publisher and rights holder of this work is Research Institute for Nature and Forest (INBO). To the extent possible under law, the publisher has waived all rights to these data and has dedicated them to the Public Domain (CC0 1.0). Users may copy, modify, distribute and use the work, including for commercial purposes, without restriction.

GBIF Registration

This resource has been registered with GBIF, and assigned the following GBIF UUID: ab6a6c25-1562-426d-9fdd-c4d9529f076c.  Research Institute for Nature and Forest (INBO) publishes this resource, and is itself registered in GBIF as a data publisher endorsed by Belgian Biodiversity Platform.

Keywords

Samplingevent; Observation; Meetnet Agrarische Soorten; birds; mammals; agrobiodiversity; Flanders

Contacts

Ward Langeraert
  • Metadata Provider ●
  • Originator ●
  • Point Of Contact
Research Institute for Nature and Forest (INBO)
BE
Hans Van Calster
  • Originator
Research Institute for Nature and Forest (INBO)
BE
Stijn Cooleman
  • Metadata Provider ●
  • Originator
Research Institute for Nature and Forest (INBO) / Belgian Biodiversity Platform
BE
Maria-Rose Eves Down
  • Metadata Provider ●
  • Originator
Research Institute for Nature and Forest (INBO)
BE
Johannes Jansen
  • Originator
Research Institute for Nature and Forest (INBO)
BE
Kenniscentrum akkervogels - Grauwe Kiekendief
NL
SOVON
NL
Vlaamse Landmaatschappij
BE
Agentschap voor Natuur en Bos
BE
Agentschap voor Landbouw en Zeevisserij
BE

Geographic Coverage

Flanders, Belgium

Bounding Coordinates South West [50.67, 2.53], North East [51.51, 5.94]

Taxonomic Coverage

This dataset covers 203 bird species and 15 mammal species (excl. 3 species aggregates).

Kingdom Animalia
Phylum Chordata
Class Aves (Birds), Mammalia (Mammals)

Temporal Coverage

Start Date / End Date 2018-04-05 / 2025-11-15

Project Data

“Meetnet Agrarische Soorten” (MAS) is a Flemish monitoring plan of wild birds and mammals in agricultural areas. The aim is to gain insight into the status of bird populations, trends therein, regional differences and the effect of conservation measures taken for birds in agricultural habitat. Since 2018, counts have been taking place in limited locations according to the MAS protocol. Since 2022, the monitoring network has been expanded across different agricultural regions and since 2024 the monitoring network covers the whole of Flanders. The rollout until 2023 is part of the MAS pilot project. The further rollout to all agricultural regions in Flanders is part of the project “Meetnet Biodiversiteit in het Agrarisch Gebied” (MBAG).

Title Meetnet Agrarische Soorten
Identifier MBAG
Funding Flemish Government
Study Area Description Flanders, Belgium
Design Description The delineation of the sampling frame and sampling design is described in Langeraert et al. (2025b). We provide a summary here: The sampling frame was delineated by crossing the agricultural regions of Belgium with the contour of Flanders. In this, open and semi-open landscapes were selected. Non-agricultural uses, such as parks, residential areas, military zones, industrial areas and cemeteries, were excluded based on OpenStreetMap data to ensure focus on agricultural areas. In the remaining area, counting points were placed along public roads and trails. To ensure that counting points were located in areas with sufficient agricultural land, the VITO 2019 land use map (Poelmans et al., 2011) was used. Finally, points were excluded with too poor visibility through the calculation of a visibility index. For sampling purposes, each Flemish agricultural area was divided into four strata (sub-areas). This stratification was done based on species protection programme areas (inside versus outside) and landscape openness (open versus semi-open). Based on the sampling frame, a spatially balanced and stratified sampling was then done to ensure a good distribution and representation of landscape elements.

The personnel involved in the project:

Johannes Jansen
  • Point Of Contact
Ward Langeraert
  • Point Of Contact

Sampling Methods

Sampling happens according to the Dutch MAS protocol (Teunissen et al., 2019). Observations within a radius of 300 m from the counting point are entered with a simple breeding code via the mobile entry in Avimap or on a field map and then via entry on the Sovon website. Each point is counted four times per year in the periods: 1-20 April, 21 April -10 May, 11 May - 10 June and 21 June - 15 July. There must be at least 7 days between consecutive visits to the same point. The counting happens from sunrise until no later than 5 hours afterwards for exactly 10 minutes per point. In addition to the standard monitoring data, the dataset also contains extra records (e.g. observations outside the radius of 300 m or outside the counting periods).

Study Extent At up to 1200-some counting points, located along public roads and trails across agricultural areas in Flanders, farmland birds and mammals are surveyed four times each year during spring and early summer. The delineation of the sampling frame is described in Langeraert et al. (2025b) and summarised under ‘Design description’ here in this dataset’s metadata submenu ‘Project’.
Quality Control Data are collected using a predefined sampling protocol. Checks are performed in the R programming language (R Core Team, 2025) via a reproducible pipeline (Langeraert et al., 2025a).

Method step description:

  1. Researchers from INBO and volunteers define and enter observations into Avimap (app/portal of Sovon, https://www.sovon.nl/).
  2. Annual data export from the Sovon WFS Server in the format of .gpkg files (see protocol https://protocols.inbo.be/2024.07/index.html).
  3. Data control and cleanup is done in R via a reproducible pipeline. The pipeline also contains steps for Darwin Core mapping and making the dataset publishable on GBIF.
  4. The dataset is published and registered with GBIF.

Bibliographic Citations

  1. Eves Down M.‐R., Langeraert W. & Jansen J. (2025). DMP voor het Meetnet Agrarische Soorten (MAS): Steekproefkader en daar voorbij. Instituut voor Natuur‐ en Bosonderzoek, België. https://www.vlaanderen.be/inbo/publicaties/dmp-voor-het-meetnet-agrarische-soorten-mas-steekproefkader-en-daar-voorbij
  2. Langeraert W., Cartuyvels E. & Van Calster H. (2025a). MBAG ‐ MAS (akkervogels). https://github.com/inbo/mbag-mas
  3. Langeraert, W., Van Calster, H., Van Overmeeren, N. & Jansen, J. (2025b). Meetnet Agrarische Soorten: van lokale pilootstudie tot een Vlaams monitoring instrument. Steekproefdesign voor de monitoring van agrarische fauna in Vlaanderen. Rapporten van het Instituut voor Natuur‐ en Bosonderzoek 2025 (30). Instituut voor Natuur‐ en Bosonderzoek, Brussel. DOI: 10.21436/inbor.126766638 https://doi.org/10.21436/inbor.126766638
  4. Poelmans L., Janssen L. & Hambsch L. (2021). Landgebruik en ruimtebeslag in Vlaanderen, toestand 2019. VITO‐rapport (2021/RMA/R/2458). Uitgevoerd in opdracht van het Vlaams Planbureau voor Omgeving, Brussel. https://archief.algemeen.omgeving.vlaanderen.be/xmlui/handle/acd/449392
  5. R Core Team (2025). R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria. https://www.r-project.org/
  6. Teunissen W.A., Wiersma P., de Jong A., Kleyheeg E. & Vergeer J.-W. (2019). Handleiding voor het Meetnet Agrarische Soorten. Sovon Vogelonderzoek Nederland, Nijmegen. https://www.sovon.nl/tellen/telprojecten/meetnet-agrarische-soorten-mas

Additional Metadata

We would like to thank the many volunteers for their input in creating this dataset.

Alternative Identifiers ab6a6c25-1562-426d-9fdd-c4d9529f076c
https://ipt.inbo.be/resource?r=meetnet-agrarische-soorten-vlaanderen