NDFF National garden butterfly count

Dutch Butterfly Conservation has organised the annual national garden butterfly count since 2008. Every first weekend of August, anyone can participate by counting the number of butterflies in their garden, noting down that number and/or reporting it via the 'Vlindermee' app. Dataset available via https://www.ndff.nl/english / [e-mail] Positive observations without zeros. NDFF protocol 3.003 https://www.ndff.nl/overdendff/validatie/protocollen/3-003-protocol-waarnemingen-tuinvlindertelling/