Combining radio telemetry, IoT-based telemetry, capture–mark–recapture, and citizen science to study movement ecology in the swallowtail butterfly <i>Papilio machaon</i>

<jats:p>Understanding insect movement is fundamental to ecology and biodiversity conservation, yet direct observations of dispersal remain challenging because insects are small, highly mobile, and difficult to track. Although capture–mark–recapture (CMR), radio telemetry, and citizen science are increasingly used to investigate insect movements, their complementary strengths and limitations have never been systematically compared within a single study. Here, we present the first systematic comparison of conventional radio telemetry, Internet of Things (IoT)-based telemetry, CMR, and citizen science for investigating butterfly movement ecology, using the swallowtail butterfly &lt;i&gt;Papilio machaon&lt;/i&gt; as a model species. We combined CMR, battery-powered NanoPin telemetry, solar-powered IoT-based BlūMorpho telemetry, and a citizen-science reporting campaign to investigate a hilltopping population near Rottenburg, southwestern Germany. We additionally evaluated the influence of different confidence thresholds on movement estimates derived from BlūMorpho telemetry. CMR provided estimates of population size, recorded minimum age, and local movements, whereas NanoPin telemetry reconstructed high-resolution movement trajectories over short periods. BlūMorpho telemetry enabled repeated detections over several weeks, revealing prolonged hilltop fidelity, habitat use, and cumulative movement distances exceeding 60 km. Citizen science documented a butterfly moving at least 65.9 km within 12 days, representing, to our knowledge, the longest published dispersal distance for P. machaon. Estimated movement distances were highly sensitive to the selected confidence threshold, whereas habitat associations remained remarkably robust. Our results demonstrate that no single method captures the full complexity of butterfly movement ecology. Instead, CMR, conventional radio telemetry, IoT-based telemetry, and citizen science provide complementary ecological information, contributing mainly to estimates of population size and recorded minimum age, high-resolution movement behaviour, habitat use, site fidelity, and long-distance dispersal. In addition, the biological validation of confidence thresholds provides a practical framework for filtering and interpreting crowd-sourced telemetry data, facilitating the application of this emerging technology in insect movement studies.</jats:p>