Provide supplementary food through the establishment of food populations
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Overall effectiveness category Unknown effectiveness (limited evidence)
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Number of studies: 4
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Supporting evidence from individual studies
A replicated study between over the winters of 1946-1947 in wetlands in Alabama, USA (Givens & Atkeson 1952), found that waterfowl used rye grass Lolium multiflorum plantings as an alternate food source. Waterfowl used the rye grass plantings extensively, often in preference to other green browse, as it added a distinct microhabitat to mud flats exposed during winter draw-down of the reservoir. Rye grass was the only crop able to withstand periodic flooding and silting over the winter period and thus became a reliable food source for waterfowl. Experimental, small-scale plantings began in 1946. Large-scale plantings began in the fall of 1947. Higher mud flats are preferable as planting sites and the rate of seeding is 50 pounds per acre.
Study and other actions testedA small replicated study over the winters of 1964-1968 in 2 fenced experimental fields (39 ha each) within a coastal wildlife refuge in Texas, USA (Shields & Benham 1969), found that whooping cranes Grus Americana preferred supplemented grains and seeds to planted crops during periods of low food availability. On average, 164 and 100 whooping crane use-days were observed for planted crops from October-December and January-April respectively, whereas the average use-days over the same periods for spread grain were 390 and 524 (3607 use-days over the study period in total). Whooping cranes significantly preferred hegari Sorghum vulgare, corn and wheat. Whooping cranes preferentially fed along the tidal flats in good weather. However, the crops (especially wheat, corn, legumes, peanuts and peas) were extensively used by sandhill cranes Grus canadensis, snow geese Chen hyperboreanI and Canada geese Branta canadensis (181 000 goose and 233 000 crane use-days in total from 1964-1967).
Study and other actions testedA study in a small (1.4 ha) artificial lake in central Sweden between 1978 and 1980 (Andersson & Danell 1982) added wheat straw and hay to the lake in an attempt to boost macroinvertebrate biomass and wildfowl numbers. However, the number of wildfowl did not appear to be affected by the addition and there was little change in invertebrate biomass. The authors suggest that high populations of invertebrate predators were responsible for the lack of change.
Study and other actions testedA replicated, controlled study from 1989-1992 in 3 experimental blocks and 5 control blocks (all 1 km2) within a forest region in the Yukon, Canada (Rohner & Krebs 1998), found that artificially increasing the density of prey did not alter the territorial or social structure of great horned owls Bubo virginianus. Experimental owls on food-enriched territories did not show a difference in home-range size and patchiness of spatial use compared with control owls. However, the distances of owl locations to treatment blocks were significantly closer to experimental centre-points than expected by chance (on average, 0.6 km closer). At a larger scale, no owls vacated their territories to use experimental plots and no owls switched to a nomadic strategy. The authors speculate that territorial behaviour prevents large aggregations of predators at an intermediate spatial scale. Experimental blocks were provided with commercial rabbit chow added weekly all year; snowshoe hare Lepus americanus densities were 2.8-10.3 times higher than in control blocks.
Study and other actions tested
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This Action forms part of the Action Synopsis:
Bird ConservationBird Conservation - Published 2013
Bird Synopsis