Effects of Simulated Dusk and Dawn on Activity and Feeding of Puerto Rican Crested Toads (Peltophryne lemur) in Captivity.

Night light may affect captive amphibians in alternative ways. Captive amphibians may be more active and consume more prey if a dim light is provided at night that illuminates their surroundings, or light may deter them from emerging at night to avoid being detected. We examined how the presence of a dim night light simulating a natural dusk and dawn influenced the activity and feeding of Puerto Rican crested toads (hereafter "PRCTs"), a species of conservation concern currently raised in 17 AZA-affiliated breeding facilities across the United States and Canada. We used video cameras to monitor toads in three terrariums with no light at night for 10 days, then replicated this observation period with a dim night light turned on above each terrarium to mimic a natural dusk and dawn from 7 to 10 p.m. and 4 to 7 a.m., respectively. Toads did not differ in prey consumption between treatments, but toads showed trends of greater activity above the substrate and toads moved more frequently when a dim light was provided. The presence of a night light had no effect on when toads emerged at night or when they hid in the morning. Toads may have been more active above the substrate when a dim light was provided because it improved visibility and encouraged interaction with their surroundings. It remains to be determined how light at night affects other aspects of captive amphibian welfare, such as physiological markers of stress, reproductive ability, and susceptibility to disease.