American Kestrel, Falco sparverius
Rodent problems on organic farms
Ecologically-based rodent management
Using owls and kestrels to control rodents
•Barn owls (Tyto alba)
and American kestrels (Falco sparverius)
can significantly reduce rodent populations, especially when present on a farm together. Owls hunt mostly at night (nocturnal) and kestrels hunt during the day (diurnal). This full
night and day predator pressure creates a stressful environment for rodents, causing them
to forage (and likely reproduce) less.
•Barn owls have
a preference for rodents, and a nesting pair may eat 1000 small mammals during one breeding season (Jan-June). A pair of kestrels
can eat up to 500 voles during their three month breeding season (April-June in Oregon).
When hovering over vole territory, kestrels can see the UV reflectance of vole urine and feces, making them very deadly predators.
and perches are key to attracting owls and kestrels to a farm. Nest boxes can be purchased, or built from
downloadable plans. Nests should be at least 5 meters (15 feet) above
the ground, in an open area, or on or in a barn. November through January (prior to the breeding season)
is the best time to add (or clean) nesting boxes.
•In open areas where trees are not present, perches help to attract kestrels. Raptors
use perches for hunting, feeding and resting. T-shaped perches should be 4-5 meters (12-15
•Raptors are more successful hunting
in areas with shorter grass and vegetation. Keeping farm areas occasionally mowed will help attract owls
and kestrels, and keep rodent populations in check.
Our experience at Natural Harvest Farm
•We have one owl and two kestrel nesting boxes. One kestrel box (on the east side
of our barn) was used this year, with a pair of kestrels successfully raising chicks. A pair of owls began nesting inside our barn in late June, with chicks born in July.
•We also have a 6 meter (20 foot) perch above our greenhouse, but this is rarely used by the kestrels.
The kestrels prefer to perch at two sets of mature trees that, together with the
nest, form a triangle over vegetable fields (and prime hunting grounds)
•Together with our other prevention and control methods (mowing, cats and traps), the kestrels have been good (and entertaining)
help to minimize rodent crop damage.
The bottom line
- Duke, G, Janni, K 1998, “Natural bird control around dairy facilities”, University of Minnesota extension
- Ingels, C 1992, “Birds of prey assist
farmers”, Sustainable agriculture,
- Ingels, C 1995, “Use of barn owls
to control rodents on farms”, Sustainable agriculture, http://ucanr.org/alf_symp/1995/95-95.pdf
- Kibbutz Sde Eliyahu, “Using raptors
in agricultural biological pest control”, http://www.sviva.gov.il/Enviroment/Static/Binaries/Articals/pest_control_1.doc viewed July 2008.
- Korpimaki, E, Norrdahl, K 1991, “Numerical and functional responses of kestrels, short-eared owls, and long-eared
owls to vole densities”, Ecology,
- Meerburg, BG, Bonde, M, Brom, FWA, Endepols, S, Jensen, AN, Leirs,
H, Lodal, J, Singleton, GR, Pelz, HJ, Rodenburg TB, Kijlstra, A 2004, “Toward sustainable management of rodents in organic animal husbandry”, NJAS-Wageningen journal
of life sciences, pp 195-205.
L, Crait, J, Edge, DE, Wang, G 2001, “Response of American kestrels and gray-tailed voles to vegetation height and supplemental
perches”, Canadian journal of zoology, pp 380-385.
- Zampiga, E, Gaibani, G, Csermely, HF,
Hoi, H 2006, “Innate and learned aspects of vole urine UV-reflectance use in the hunting behavior of the common kestrel
Falco tinnunculus”, Journal of avian biology, pp 318-322.
- Photo credit: Pedro Genaro Rodriguez,