The magnitude of ecosystem services delivered by natural enemies in agriculture is subject to both local and landscape habitat variables. Wine grape farmers in the Napa Valley have erected nest boxes to attract barn owls (Tyto alba) to their properties in an attempt to help control economically damaging rodent pests, find environmentally sustainable treatment methods, and support conservation of local fauna. The foraging behavior of these owls in vineyards, however, has yet to be rigorously examined, and the effect of local and landscape characteristics on prey delivery is unknown. We installed remote video cameras in boxes and monitored prey delivery of nesting barn owls throughout the breeding season.
Results/Conclusions
Preliminary data suggests that approximately 152 prey items were consumed per fledging from the time of hatch until the time of dispersal. The rate at which prey are delivered was lowest during the first week (1.05 items per night per chick), peaked near weeks 4 and 5 (2.48 items per night per chick) and tapered off from weeks 6 to 9 (1.69 items per night per chick). Preliminary results also indicate that different levels of local and landscape heterogeneity may be responsible for variation in prey delivery rates. Understanding these patterns can inform the strategic deployment of nest boxes to maximize the provisioning of this pest control service, and it may also incentivize habitat conservation that can increase the occupancy and local foraging by owls in vineyards.