Light Bait Improves Capture Success of Aquatic Funnel-Trap Sampling for Larval Amphibians

Aquatic funnel traps are a non-destructive means of surveying amphibians in lentic habitats, particularly as compared to dip-net surveys that disturb aquatic vegetation and the substrate, and affect the water column through increased turbidity. The objective of this study was to examine the utility of glow stick-baited aquatic funnel traps for larval amphibians, with a particular emphasis on ambystomatid larvae. We sampled 12 isolated ponds in the Mid-Atlantic Coastal Plain of South Carolina between April and June 2010 and used detection/non-detection capture data to model the probability of capturing larval amphibians in baited and un-baited funnel traps. Further, we used count data (captures per trap) to examine whether glow stick-baited traps captured more amphibian larvae than un-baited traps. We captured four Ambystoma species (A. mabeei, A. opacum, A. talpoideum, and A. tigrinum) and tadpoles from the families Bufonidae, Ranidae, and Hylidae in light-baited funnel traps. Captures of both Ambystoma larvae and tadpoles were positively associated with light-baited traps, and we were 8.8 times more likely to capture Ambystoma larvae and 5.7 times more likely to capture tadpoles in glow stick-baited traps as compared to un-baited traps. Our results indicate that glow sticks can greatly improve capture success of larval amphibians in funnel traps, and we recommend their use as an active sampling method that is unbiased by surveyor experience and skill-level.