Methods

Sovon has a diverse range of knowledgeable ecologists, accomplished in fieldwork, statistical analysis and application. 

Breeding birds

For the last few decades, Sovon has made an inventory of birds breeding in the Netherlands according to a standardized protocol. The consensus of breeding birds is necessary to establish the population number and distribution, and any variations that may occur. 

Overwintering and migratory birds

For a large number of bird species, is the Netherlands an important phase in overwintering birds’ annual cycle and as a stopover for birds on longer migration routes. To determine the number and distribution of birds outside of their breeding season, as well as the changes in trends, we use a diverse range of methods. These methods include; census of roosting sites, monthly counts during the winter in important wetland areas, and an annual count in January of 20 permanent areas throughout The Netherlands. In addition, there is monitoring of migratory species with respect to the species, number of birds, timing and changes in stopover areas. 

Ringing research

Ringing birds with unique codes falls under the jurisdiction of the Vogeltrekstation. We organize the project Constant Effort Sites in collaboration with the Vogeltrekstation. During a few days in the spring and summer, the birds are caught and ringed with standardized methods; the data is applied to calculate the reproduction and survival of the species.  

Furthermore, coloured rings are more progressively utilized as the probability of re-sightings are far greater then with metal rings. Thus, reducing the number of ringed birds that are required to ensure an accurate representation of the species numbers and movements.