Reflector
Mirrors and reflectors work on the principle that sudden bright flashes of light produce a startle response and drive the bird from an area. However, the response of free-living birds to mirrors has been investigated in only a handful of species. Foraging by black-capped chickadees Parus atricapillus at feeding stations was depressed by the presentation of either a standard mirror or an aluminium foil covered mirror; feeding was depressed the most by the standard mirror. When placed in nesting territories mirrors evoked aggressive responses from blue grouse Dendragapus obscurus and glaucous-winged gulls Larus glaucesens (mirror combined with playback of gull calls). Reflective objects have been reported as being effective in deterring raptors, such as sparrowhawks and goshawks, from game release pens. Experiments in Europe showed that large silvered balls were effective in protecting reared game and chickens from diurnal raptors, particularly sparrowhawks and goshawks. Various gamekeepers in the UK also advocate the use of reflective objects. Opportunistic trials using such suspended materials successfully ended sparrowhawk predation at three different release pens. Mirrors and reflectors have also been found to be inexpensive but effective against waterfowl, gulls and some herons. However, although aluminium pie plates suspended on varying lengths of twine deterred some waterfowl species, ducks were regularly seen to swim within 4-5 m of the reflectors. In a survey of 336 fish hatchery managers in eastern USA, eight reported using tin reflectors of which seven said they had limited or no success as a depredation control technique. In the same survey only one manager used mirrors and that was unsuccessful. Mirrors placed inside nest-boxes did not deter starlings from nesting within. A device consisting of a rotating pyramid of mirrors has been recommended for preventing crow damage to seedling corn. This device is available in the UK and the manufacturer claims it is effective over four hectares against pigeons, blackbirds, starlings and crows on a variety of crops, but no scientific research has been can carried out to substantiate these claims. Although easy and inexpensive to put up and easy to relocate, the effectiveness of mirrors and reflectors as a bird scaring technique is variable. As they are only effective when they reflect sunlight and so are useless before sunrise, they are best combined with other methods of scaring.
More:
