Surveying biodiversity in landscapes
At the landscape level, biodiversity is surveyed by fieldworkers walking a track (transect) predefined on a map for each 1-km2 sampling area, recording each species they find.
Regarding vascular plants and butterflies, each BDM transect is 2.5 kilometers. Surveying breeding birds, however, requires tracks to be laid out in such a way as to cover the major part of each sampling area. At three up to no more than five kilometers, these tracks are considerably longer than plant and butterfly transects.
Visiting a sampling area once is generally not enough: As a rule, sampling areas are being surveyed two or three times a year in order to take seasonal differences in species composition into account. For butterfly surveys, sampling areas even must be walked up to seven times.
Surveying step by step
This series of images shows a BDM fieldworker surveying species in a sampling area. For a larger view, please click on the images.
Each sampling area extends over one square kilometer. Following a precisely set trail within an area (a so-called “transect”), field biologists will look for vascular plant species by the sides of roads and paths.
Each transect is 2.5 kilometers long. Any species found on or along a transect is entered into the BDM smartphone app.
Every once in while, a biologist must take a closer look to identify just exactly what has been found.
Butterflies are sampled along transects as well. Whenever it is not possible to identify a specimen in flight, it will be netted.
Inside its little plastic tube and well protected from harm, the butterfly can be viewed in detail. All identified species will be recorded using the BDM smartphone app.
Once identified, each little critter is promptly released.
Whenever possible, breeding birds are surveyed covering all of a sampling area. For this purpose, the Swiss Ornithological Institute’s mostly volunteer fieldworkers will visit each area three times a year (only twice in the mountains).
Surveying in motion
The roughly three-minute video allows you to accompany BDM fieldworkers surveying species diversity in landscapes. Please be patient: After clicking the start button, it takes a few seconds for the video to start.