Volume 223, 1 May 2016, Pages 167–174
Sara M. Kross, ,
- Department of Wildlife, Fish & Conservation Biology, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States
- Received 27 October 2015, Revised 18 February 2016, Accepted 1 March 2016, Available online 9 March 2016
Highlights
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- Barn owls may provide valuable vertebrate pest control services for farmers.
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- Diet of nesting barn owls was measured across a gradient of different crop types.
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- Barn owls nested or roosted in over 55% of nest boxes.
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- 99.5% of prey were agricultural pest species.
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- The importance of different prey species in owl diet varied with crop type.
Abstract
Barn owls (Tyto alba)
are the most widespread raptor species on Earth, and because they are
thought to provide natural vertebrate pest control services, farmers in
some agricultural regions have encouraged barn owls to breed and hunt on
their farms by installing artificial nest boxes. However, barn owl
populations are declining in some agricultural regions, which may be a
result of changes in land use and agricultural intensification. We
studied barn owl diet and nest box occupancy in an intensive
agricultural landscape in the Central Valley of California to measure
whether agricultural land use affected barn owl diet. We collected 415
viable pellets from 25 active nest boxes over two breeding seasons and
compared these results with agricultural land use types within a 1-km
radius of each nest. Mice (Mus musculus and Reithrodontomys megalotis)
were the most numerous prey and the most important by biomass, but
their importance in barn owl diet declined with higher proportions of
perennial crops in the surrounding landscape. California voles (Microtus californicus)
were less important by number, but still represented a significant
proportion of the biomass consumed by owls in our study area. Pocket
gophers (Thomomys spp.) were consumed less often but were also
an important source of biomass. Furthermore, barn owls nesting in areas
with higher proportions of perennial crops consumed more gophers and
fewer voles, many of which were juveniles, suggesting that gophers are
more abundant and a more important part of barn owl diet in perennial
crop areas. Over 99.5% of prey items in barn owl diet were agricultural
pests and owls are therefore likely to provide valuable pest control
services for growers in our area, although the species consumed may vary
with crop types with implications for pest-control.
Keywords
- Tyto alba;
- Pest-control;
- Land use change;
- Raptor;
- Ecosystem services
Copyright © 2016 Elsevier B.V. All rights reserved.
