Figure 4

Contribution of professional vs. non-professional observers to the detection of COTS. Spatial range of COTS occurrences, mean observation density and number of COTS detection per abundance categories for professional (PROF), non-professional (NON PROF) and combined observers. Range size: number of 5 km × 5 km geographical quadrats that COTS were detected in; Mean observation density: average number of COTS reports per geographical quadrat; Single COTS: number of reports of single COTS; Aggregations: number of reports with less than 100 COTS; Potential outbreaks: number of reports with more than 100 COTS.