Changes in relative population size detection rates of great crested newts （Triturus cristatus） over time

摘要

Amphibian populations have been shown to be in decline for the past four decades in part owing to habitat degradation and loss. In the United Kingdom, when faced by habitat works through development, consultant ecologists must undertake surveys for European protected species such as the great crested newt under licence following standardised guidance. However, previous studies and survey guidance present an unclear picture in reference to the ideal time of night to undertake sampling for this species. In this paper, an experimental review of the most effective times for detecting population sizes of great crested newts is presented. Sampling was undertaken at Scotland's largest great crested newt population during the peak breeding season repeatedly between sunset and sunrise a total of six times. The results show a significant non-linear relationship between the relative detection rate of great crested newt populations over time with a peak of detectability at 141 minutes after sunset, suggesting that between 60-180 minutes following sunset is the best time to undertake surveys for this species. These data also show a significant peak of great crested newt presence at an air temperature of 3.5 °C which is below the reported critical minimum. However, water temperature which corresponded to peak newt presence was 10.4 °C suggesting this may be a crucial component of accurate great crested newt surveillance.