Avian predator management for vole biological control: positive and negative collateral effects on red-legged partridge abundances

Resumen del trabajo presentado a la 10th European Vertebrate Pest Management Conference, celebrada en Sevilla (España) del 21 al 25 de septiembre de 2015.-- et al.Nest-box installation to increase raptor numbers is an environmentally friendly technique to prevent vole plagues in agricultural systems that may help to reduce the dangerous use of anticoagulants. However, the high abundance of raptors may produce undesired effects on other non-target species of economic interest. Nest box installation on poles since 2009 increased population numbers of common kestrels Falco tinnunculus in our study agricultural areas, but also increased numbers of common buzzards Buteo buteo as they use poles as perches for hunting. We studied the effect of this raptor increase on the abundance of the red-legged partridge Alectoris rufa, a gamebird species of great socioeconomic interest in the Iberian Peninsula. For this purpose the abundance of kestrels, buzzards and partridges were monitored during five years by road surveys three times each year (April, July and November), in six agricultural areas of similar size (2000 ha each) and with (nest-box areas) and without (control areas) nest box installation. The three nest-box areas counted with 100 kestrel nest-boxes placed on poles. Our results showed that kestrel and buzzard number increases seems to have a negative effect during spring time on partridge abundances. However, a positive effect of raptor increase on partridge abundance was observed during summer time with no obvious effects on partridge abundances during winter. We suggest that partridges tend to avoid the high density of predators during the breeding season while just after breeding (July), higher densities of non partridge-specialist predators might provide protection to partridges against larger size raptors.Peer Reviewe