Abra F.D., M.P. Huijser, C.S. Pereira & K.M.P.M.B. Ferraz. 2018. How reliable are your data? Verifying species identification of road-killed mammals recorded by road maintenance personnel in São Paulo State, Brazil. Biological Conservation 225: 42-52.
Across the world, many wildlife studies rely on data collected by volunteers. Roadkill studies often rely on data collected by non-experts including road maintenance personnel and volunteers, but data quality control is rarely applied. We investigated whether maintenance personnel correctly identiﬁed the species of road-killedmammals along toll roads in São Paulo State, Brazil. We investigated 3222 images of road-killed animals and compared the original species descriptions by road maintenance personnel (non-experts) with our identiﬁcation (experts). We also presented images of alive and road-killed mammals to road maintenance personnel (n=179) and asked them to describe the species. We found that road maintenance personnel typically correctly identiﬁed certain common, large, or highly recognizable species. However, rare or rarely seen species, species that resemble other species (e.g. small wild canids and felids), or species that are not highly recognizable were often misidentiﬁed, ambiguously described, or not identiﬁed at all. We also found that the ability of road maintenance personnel to correctly identify the most common road-killed small wild canids and felids is dependent on the context. When similar species are rare, road maintenance personnel typically correctly identiﬁes the most common road-killed small wild canids and felids. However, common small canids and felids are not reliably identiﬁed if similar species are more abundant. To improve the reliability of species identiﬁcation by non-experts, we recommend training in species identiﬁcation, including images with a scale to accompany all roadkill records, and veriﬁcation of the roadkill records and associated images for selected species by experts.