Comparison of footprint tracking and pitfall trapping for detecting skinks

Inventory and monitoring of biodiversity requires effective sampling tools. Footprint tracking tunnels, developed in New Zealand to monitor small mammals, may also be useful for sampling lizards and other reptiles but more research is needed to verify this. To that end, we compared the detectability of terrestrial skinks using two methods: pitfall trapping and footprint tracking. In New Zealand, the former is the traditional method for sampling skinks, while the latter is routinely used to monitor populations of introduced rodents and mustelids. In January 2019, we operated paired grids containing 5 × 5 arrays of pitfall traps and standard rodent tracking tunnels on Tiwai Peninsula in Southland, South Island, and compared the daily proportions of traps and tunnels that detected skinks via captures and footprints, respectively. Overall, tracking tunnels were approximately twice as likely to detect skinks as pitfall traps. Additional research is required to: (1) test the relative efficacy of footprint tracking versus conventional detection methods on other lizard and reptile species; (2) investigate alternative tunnel designs and long-life lures; and, (3) calibrate footprint tracking rates against density estimates to assess suitability for monitoring.