Assessing bird diversity in Neotropical rainforests: A comparative study of camera traps and mist nets reveals complementary sampling approaches

Abstract Different sampling methods are used to study bird diversity in the tropics, mist nets being one of the most common approaches. However, camera traps have been used for this purpose in the last 20 years. We compared the performance of mist nets and camera traps in sampling the diversity of understory and sub-canopy birds in a Neotropical rainforest. Given its high biodiversity, obtaining accurate bird diversity estimates in these forests is a challenging task. We sampled secondary forest patches in the Colombian central Andes between 2019 and 2021. We compared the effectiveness of both methods based on six comparison criteria (body size, foraging stratum, detection difficulty, habitat specialization, population trend, and migratory status). We recorded a total of 99 bird species: 92 species were captured using mist nets and 37 species using camera traps; 30 species were detected using both methods (mainly generalist and abundant birds). Mist net’s effectiveness was 83%, while camera trap effectiveness was 68%. Differences in sampling effectiveness were mainly determined by body size, as small birds were captured using mist nets, while camera traps often recorded large birds. However, detection difficulty and habitat specialization were also relevant. Camera traps effectively recorded ground-dwelling species that were not captured in mist nets. In contrast, those birds that forage in the sub-canopy stratum were mainly captured in the mist nets but not detected in camera traps. Although both methods detected different species, we found similar patterns regarding estimated species richness among different categories of body size, detection difficulty, population trend, and behavior, but not for habitat specialization. As both methods have advantages and limitations, using mist nets and camera traps together would improve bird diversity estimations. We urge investigators to explore canopy ecology with camera traps, as they provide long-term information that cannot be obtained with other methods.