During recent years it has become increasingly common that volunteer citizens help to collect ecological information and carry out conservation actions over vast geographical areas that scientists alone could not cover.

Researcher Andrea Santangeli from the University of Helsinki, Finland, in collaboration with researchers from France and Spain, used this kind of citizen science data to find out which action performs best at protecting nests of the Montagu's harrier in France. This raptor nests on the ground of farmland in western Europe and its nests are often destroyed by mechanical harvesting operations and by predators.

The researchers found out that by applying a fence around a nest proved to be a very effective, cheap and fast solution for protecting nests from harvesting operations as well as from predators.

The researchers have also produced a map that shows where across France citizen science efforts could be directed in order to provide the highest benefits from nest protection to the harrier.

"Protecting nest from mechanical harvesting by leaving a small buffer of standing crop around the nest is the most commonly used intervention in France. However, after the field is harvested, the retained nest may be easily detectable on the bare field. Predation at these nests can be severe - it generally counterbalances most of the positive impacts derived from protection from harvesting," Andrea Santangeli describes.

Andrea Santangeli and his colleagues believe that this kind of evaluation studies, that take into account multiple factors, are essential in order to fully understand the outcomes of different conservation actions. Also, citizens' efforts provide an excellent mean for conservation, but there are many ways to improve their potential benefits to nature.

"There is a need for coordinating and balancing volunteer citizens' efforts across large areas in France in order for their efforts to be as effective as possible. In this line, there is much space for improvement, at least regarding the Montagu's harrier case."