Volunteers have been involved in nature observations for decades through citizen science
initiatives, providing large data sets as well as problem identification that allow
a more complete understanding of many natural phenomena. Although communication is
a core component in citizen science, the key factors that determine its effectiveness
in national and transboundary campaigns aimed at broad audiences have remained unclear.
Using the pan‐European citizen science campaign ‘Looking for Cowslips’ spanning across
31 European countries as an example, we explored the main communication facilitators
and barriers campaign organisers face in different European regions when engaging
the public in citizen science. To do so, we conducted interviews, questionnaires and
discussion groups with the campaign organisers. The results indicate that communication
in citizen science initiatives poses a challenge, particularly for researchers, who
often do not have sufficient time or means for the necessary engagement and communication
efforts. In addition to the ecological characteristics of the focal species in the
different regions of Europe, the key aspects that need to be considered for planning
effective communication in transboundary citizen science projects include various
socio‐cultural factors, such as the traditions related to citizen science in different
countries as well as local indigenous knowledge. Our study shows that collaboration
between academic institutions and environmental non‐governmental organisations, but
also the contribution by local co‐organisers at the national level, is crucial for
the effectiveness of international citizen science campaigns. In addition, facilitators
and barriers of communication need to be considered in each region separately as even
at the European scale, we observed a high variability of environmental and socio‐cultural
settings. Synthesis . In an era of detrimental consequences of human activities on
natural ecosystems, it is vital to include society in observations to determine the
impact of environmental change on biodiversity through citizen science approaches.
Substantial advances in technological tools have helped to foster these initiatives
across vast spatial scales. Nevertheless, it is also crucial to select the right pathways
for communication to compete with vast amounts of other information and to reach potential
participants in varying socio‐cultural contexts of different countries.
