Individual study: Response of northern harrier Circus cyaneus and short-eared owl Asio flammeus to prescribed burning or mowing grassland management in sanctuaries in Jasper and Marion Counties, Illinois, USA
Herkert J.R., Simpson S.A., Westemeier R.L., Esker T.L. & Walk J.W. (1999) Response of northern harriers and short-eared owls to grassland management in Illinois. The Journal of Wildlife Management, 63, 517-523
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Mow or cut natural grasslands
A replicated and controlled study in 1990-1994 in two intensively managed grassland sanctuaries in southeast Illinois, USA (Herkert et al. 1999), found that short-eared owls Asio flammeus were more likely to nest on fields burned and mowed in the last 12 months than on controls (undisturbed for 12 months). Northern harriers Circus cyaneus hudsonius were less likely to. Mowing was conducted between 20th June and 15th July each year. This study is discussed in detail in ‘Use prescribed burning’.
Use prescribed burning on grasslands
A replicated and controlled study in 1990-1994 in two intensively managed grassland sanctuaries in southeast Illinois, USA (Herkert et al. 1999), found that northern harriers tended to nest in fields not disturbed by grassland management (burning and mowing) within the last 12 months (a total of 22 nests in unmanaged fields vs. seven in burned and grazed fields). Short-eared owl Asio flammeus nest-site selection could only be assessed in 1990: all 13 nests were in fields subject to management within the last 12 months. One study site comprised 550 ha of grassland among 10 tracts, the second 308 ha among seven tracts. Each tract comprised 3-32 ‘sub-fields’ (0.5-15 ha) usually subject to one management type (all burned or all mowed).