The Right Light: Tiger Salamander Capture Rates and Spectral Sensitivity

Abstract

Knowledge of population dynamics is critical for species of conservation concern so wildlife researchers need to take advantage of biases in animals' behaviors that could help them monitor populations. This is particularly important for amphibians because many populations are declining and difficult to observe. Attraction of vertebrates to light is a well‐known navigational cue and some fisheries strategies utilize light sources to increase catch success. To optimize population monitoring of state‐endangered eastern tiger salamanders (Ambystoma tigrinum), we tested the utility of colored glow sticks (green, orange, pink, or yellow) as bait in traps in Maryland and Delaware, USA, during 2015–2016. We then measured intensities of the colored glow sticks and estimated photoreceptive quantum catches of each color according to the spectral sensitivities of eastern tiger salamanders. We found that eastern tiger salamanders' photoreceptors had greater quantum catches of photons from green and yellow glow sticks. However, traps baited with orange glow sticks were more than twice as likely to capture eastern tiger salamanders than were traps baited with green or yellow. There were no differences in the number of salamanders caught per successful trap among glow stick colors, perhaps due to attraction of salamanders to motion from previously captured salamanders. Our results indicate that biases other than perceived intensity of light sources may drive behavioral preferences. © 2020 The Wildlife Society.

There's No Place Like Home: Influential Habitat Characteristics of Eastern Tiger Salamander (Ambystoma tigrinum tigrinum) Breeding Ponds in Maryland and Delaware

“…Five traps were placed per night in smaller ponds (mean pond area = 851.08 m 2 ± 217.71 SE) and nine traps were placed in larger ponds (mean pond area = 3,329.91 m 2 ± 639.74 SE). We placed traps haphazardly, but ≥10 m apart, in each pond and tied them to stakes or nearby vegetation at depths between 1 and 1.5 m. We baited each trap with an activated orange glow stick (20 × 0.5 cm, Play Glow) and replaced them every 24 h during the trapping period (sensu Grayson and Roe, 2007; Liebgold and Carleton, 2019). For each trap-night, traps remained in place overnight (during all nondaylight hours) and checked ≤24 h later.…”