An assessment of the use of volunteers for terrestrial invertebrate biodiversity surveys
Species’ distributions, assemblage patterns and the processes influencing these are poorly understood, and urgently require study. Use of volunteers to collect data is becoming increasingly common in biodiversity research. We assess the effectiveness of volunteers sampling terrestrial savanna invertebrates in comparison to experienced researchers, and examine the potential contribution of volunteers to terrestrial invertebrate surveys. There were relatively few differences in the diversity sampled by 54 Earthwatch Institute volunteers when compared to expert researchers. The major difference was in the results from the less spatially constrained method, where experience (microhabitat selection) most affected results, and experienced researchers performed better both quantitatively (more species sampled) and qualitatively (more unique and rare species). For the more constrained and less subjective methods, our training enabled the volunteers to quickly equal the experienced experts. Volunteers’ experience in invertebrate research influenced both the researchers’ perceptions of volunteers’ capacity and the actual performance of the volunteers. This suggests that appropriate training for the methods used can help to improve volunteers’ success with the sampling. We demonstrated that volunteers collect valid data; for the most part they sample invertebrates as effectively as a trained researcher, and that using volunteers has enormous direct benefits in terms of volume of work accomplished. For invertebrate studies using volunteers, we recommend that the subjectivity of the method be minimised, that experience is compensated for by increasing volunteer effort (two volunteers = one researcher), and that there is close management of volunteers in the field to ensure ongoing data quality. Volunteers provide a valuable resource to researchers carrying out biodiversity surveys, but using volunteers to carry out a scientifically sound project is not an easy option, and should only be implemented when volunteers would make a meaningful contribution and enable an otherwise impossible project.