Monitoring Eastern Spadefoot (Scaphiopus holbrookii) Response to Weather with the Use of a Passive Integrated Transponder (PIT) System
Eastern Spadefoots (Scaphiopus holbrookii) are probably one of the least-understood amphibian species in the United States. In New England, populations are localized and it is likely that some populations go undocumented because of the species' cryptic habits. We used passive integrated transponders (PIT tags) to monitor burrow emergence with the aid of continuously running, stationary (but portable) PIT tag readers. We monitored the activity of individual Eastern Spadefoots by placing circular antennae directly over burrows of PIT tag-implanted individuals. We monitored 18 Eastern Spadefoots from 1 to 84 nights in the spring, summer, and fall of 2009–2011. Our results indicate that, on average, Eastern Spadefoots emerged on 43% of the nights that they were monitored. Nights when Eastern Spadefoots emerged were warmer and more humid than nonemergence nights. Eastern Spadefoots were also much more likely to emerge on a given night if they had emerged the night before. Our results have improved the understanding of Eastern Spadefoot burrow-emergence patterns in the northeast region. Our findings may considerably enhance the prospect of employing nocturnal visual encounter surveys as a method for monitoring known, and detecting previously undocumented, populations of this species.Abstract
Using a toad tote to monitor burrow emergence of a PIT tagged eastern spadefoot. Note the iButton placed within the antenna. Photograph by Nicole Cudzilo.
Raw PIT tag reader (black bars) and telemetry data (cross hatching) for three monitored Eastern Spadefoots over the course of 3 nights. Vertical gray bars demarcate nighttime hours, horizontal black bars indicate detection of PIT a tag, up and down arrows indicate spadefoot position (above or below ground, respectively), and cross hatching indicates location confirmation of a burrowed spadefoot via radio telemetry (once during the day). Tag-read gaps >1 h occurring at night are classified as emergences. Note that the actual monitoring dates of spadefoots A, B, and C differ, hence the sequential numbering from 1 to 3. Note also that for spadefoot A, night 3, we considered the toad not to have emerged, as telemetry readings confirmed presence in the same burrow during both the preceding and following days.
Proportion of Eastern Spadefoot burrow emergence relative to hours from sunset.
Contributor Notes
