Predator identification and effects of habitat management and fencing on depredation rates of simulated nests of an endangered population of Hermann’s tortoises

Published source details Vilardell A., Capalleras X., Budó J. & Pons P. (2012) Predator identification and effects of habitat management and fencing on depredation rates of simulated nests of an endangered population of Hermann’s tortoises. European Journal of Wildlife Research (formerly Zeitschrift für Jagdwissenschaft 1955-2003), 58, 707-713.
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This study is summarised as evidence for the following.

	Action	Category
	Protect nests and nesting sites from predation by creating new nesting sites Action Link
	Remove or control predators using fencing and/or aerial nets Action Link

Protect nests and nesting sites from predation by creating new nesting sites

A replicated, controlled study in 2009 in open shrubland in Catalonia, Spain (Vilardell et al. 2012) found that clearing shrubs to create new nesting sites did not reduce predation of artificial western Hermann’s tortoise Testudo hermanni hermanni nests. In trials with high densities of artificial nests, predation rates of artificial Hermann’s tortoise nests in new nesting sites created by clearing shrubland (44% nests predated after 48 hours and 100% predated after 144 hours) were statistically similar to predation rates in existing natural nesting sites (100% nests predated after 48 hours). In second and third trials with lower densities of artificial nests, all nests in new nesting sites and natural nesting sites were depredated within 48 hours. Predation of artificial tortoise nests (three buried quail Corturnix coturnix eggs) was monitored in 36 square plots (of 4, 25 and 100m², numbers of each sized plot not provided) in a nature reserve. In 27 plots, shrubs were cut to 0–3% ground cover to represent new nesting areas (see original paper for details) and nine plots in a natural tortoise nesting area were not managed. In May 2009, nine artificial nests were placed in the centre of each managed and unmanaged plot and, in the 25 and 100 m plots, an additional nine artificial nests were placed in one corner of each plot (total 486 artificial nests). Nests were visited every two days for one week and weekly for up to a month. Predation was monitored by trail cameras and visual signs. The trial was repeated in June and August 2009, but with only one artificial nest in the centre and, where appropriate, corner of each plot.

(Summarised by: Katie Sainsbury)
Remove or control predators using fencing and/or aerial nets

A replicated, controlled study in 2009 in open shrubland in Catalonia, Spain (Vilardell et al. 2012) found that fencing nesting sites reduced predation by some species on artificial western Hermann’s tortoise Testudo hermanni hermanni nests and increased the time until predation occurred in one of two trials. In a first trial, artificial Hermann’s tortoise nests in fenced areas survived longer until depredation (15 days) compared to artificial tortoise nests in unfenced areas (<2 days). In a second trial one month later, all fenced and unfenced nests were depredated within three days. Authors report that fencing did not prevent predation by beech martens Martes foina, but other predators in the area (wild boar Sus scrofa, red fox Vulpes vulpes, common genets Genetta genetta and European badgers Meles meles) were successfully excluded (see original paper for details). Predation of artificial tortoise nests (three buried quail Corturnix coturnix eggs) was monitored in a nature reserve in sixteen 100 m² plots which had been cleared to 3% of shrub cover using pruning shears. Half of the plots were enclosed with a mesh fence (200 cm high). In September and again in October 2009, one artificial nest was placed in the centre of each plot. Predation was monitored by trail cameras and visual signs.

(Summarised by: Katie Sainsbury)