DOI: 10.15468/vzs4wf
title: Meetnet Agrarische Soorten - Monitoring of birds and mammals in agricultural areas in Flanders, Belgium

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).