Adding value to imperfect long-term animal monitoring data for conservation insight

Résumé fourni par la source

Long-term monitoring can provide insights into population decline of rare taxa yet is often inadequate owing to low encounter rates and poorly defined research questions. Here, we apply a multi-scale approach to investigate the ecology and long-term trends of a critically endangered lizard, the Canberra grassland earless dragon, and show that while all populations declined over 21 years of trapping, variation in population size tended to be site specific. This suggests that local, more than landscape-level, features are driving fluctuations in the remnant populations. We also showed, through contemporary occupancy surveys, that dragons preferred plots with intermediate grass tussock height (5–15 cm) and percent bare ground (6–30 %). This preference was evident across all years, trapping grids, and captures when using Land Surface Temperature and Normalised Difference Vegetation Index as proxies for temperature and vegetation structure. Taken together, these data provide compelling evidence that the dragons require intermediate vegetation cover and prefer cooler summer conditions. Overall, we demonstrate that combining long-term population monitoring, contemporary habitat sampling, and temporal satellite data sheds light on important ecological processes not evident when considering any one method alone. Our approach identified vegetation structure as a key factor limiting the dragon's distribution, providing a focus for future management of the species. More broadly, we show that adopting a multi-scale approach could enhance the value of monitoring data for rare taxa.

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