Gopherbusters? A Review of the Candidacy of Barn Owls as the Ultimate Natural Pest Control Option

Abstract

While many raptor species consume rodent pests, the behaviors and habits of barn owls make them particularly suitable candidates for consideration as a viable pest control strategy. As a cavity-nesting species, barn owls will readily nest in man-made structures including nest boxes. Barn owls are also less territorial than many other raptor species and will tolerate other pairs nesting nearby if prey is abundant. Barn owls preferentially consume rodents including voles (Microtus spp.) and pocket gophers (Thomomys spp.) in habitats where they occur, but will also switch to more abundant prey so they may be able to sustain populations even if preferred prey numbers fall. These life-history traits allow for people to inflate barn owl populations in target areas, and this has been a factor in the widespread popularity of encouraging barn owls to nest in agricultural areas to provide natural pest control of small nocturnal vertebrate pests. However, the ability of barn owls to control rodent pests has only been formally tested in Malaysian rice and palm oil agriculture, and whether barn owls are capable of controlling rodent pests to economically acceptable levels in areas such as California is as yet unknown. We extracted and combined data from field studies of barn owl nesting behavior and diet in California vineyards to predict that annually, a pair of nesting barn owls and their progeny will consume 97.85 kg of prey. We predicted that an average barn owl nest in a California vineyard will therefore consume 843 pocket gophers, 578 voles, and 1,540 other prey items, most of which are mice. At these values, a barn owl population density of one nest/10 ha may be able to offset the annual productivity of an average population of pocket gophers, but even the highest barn owl densities of one nest/2 ha would be unable to control pocket gopher populations at maximum densities and reproductive rates. While valuable for making initial predictions of the ability of owls to control small rodent pests, our prediction methods are crude, and accurately assessing the capability of barn owls to control rodent pests will require more field data and more sophisticated modeling techniques.

Multi‐year nest box occupancy and short‐term resilience to wildfire disturbance by barn owls in a vineyard agroecosystem

“…The mechanisms and nest box characteristics behind colonization, extinction, and persistence (the probability of a box remaining occupied) underlie the ability of barn owls to nest in vineyards and provide meaningful pest control. With remaining uncertainty over the ability of barn owls to control rodent damage (Labuschagne et al 2016, Kross and Baldwin 2016, Johnson et al 2018), a first step for managing their potential for this ecosystem service is confirming our understanding of their nesting preferences both with and without disturbance.…”

The History and Development of Small Mammal Control on China’s Grasslands and Potential Implications for Conservation

“…These perches are commonly used around the world as a component of ecologically based rodent management (EBRM) (Labuschagne et al, 2016;Sara et al, 2016), and in China they aim to attract raptors to areas of high rodent or pika density (See Fig. 3).…”

Can Barn Owls Help Control Rodents in Winegrape Vineyard Landscapes? A Review of Key Questions and Suggested Next Steps

“…Agricultural extension publications offered suggestions for erecting owl nest boxes (e.g., Heaton et al 2008). Barn owls are an attractive method for pest control because their nest boxes are relatively inexpensive to install and maintain (Kross and Baldwin 2016), and several natural history attributes suggest they could help reduce rodents: adults are not very territorial and can sometimes reach high densities (Smith et al 1974), they are efficient hunters and their broods demand many prey items (Durant andHandrich 1998, Taylor 1994), and in agricultural settings their diets are almost exclusively composed of rodent pests , Taylor 1994.…”

“…More recently in California, there is renewed research interest in barn owls as pest control. At the 2016 Vertebrate Pest Control Conference in Newport Beach, Kross and Baldwin (2016) used empirical field data in a predictive model and suggested that a barn owl population density of one nest/10 ha may be able help control an average pocket gopher population, but even the highest barn owl densities would be unable to control abundant and quickly reproducing pocket gopher populations. At the same conference, Browning et al (2016) reported that in Lodi, CA, mound surveys suggested that gophers declined on a vineyard with barn owl boxes relative to a control vineyard without barn owl boxes.…”