Studies investigating the removal of crows as an aid to reproductive success in other birds.

(General conclusion: it doesn't work.)


Broyer, J., J. Y. Fournier, and P. Varagnat. 1995. Effect of carrion crow (Corvus corone) reduction on predation on artificial anatid (Anatidae) nests. Gibier Faune Sauvage 12: 95-107.

Removal of crows caused little change in predation on artificial duck nests. No changes in predation rates were seen in the first year, but in the second year of removal predation on early (May) nests decreased. Predation rates on late nests (June) were unaffected in either year, being compensated for by predation by other species.


Chesness, R. A., M. M. Nelson, and W. H. Longley. 1968. The effect of predator removal on pheasant reproductive success. Journal of Wildlife Management 32: 683-697.

The authors removed skunks (Mephitis mephitis), raccoons (Procyon lotor), and American Crows, and got a gradual decline in predation on pheasant nests over three years. The effect of predator removal had no carryover benefits one year after removal. They found no conclusive effect on the presence of young pheasants in late summer. They concluded that predator removal was not economically supportable, even if the fall pheasant chick numbers increased (which they didn't).


Clark, R. G., D. E. Meger, and J. B. Ignatiuk. 1995. Removing American Crows and duck nesting success. Canadian Journal of Zoology 73: 518-522.

Nesting success of ducks in two areas where crows were removed did not differ from that of two control areas. Removing only one of a community of predators has no effect in increasing reproduction and survival of the prey species.


Parker, H. 1984. Effect of corvid removal on reproduction of willow ptarmigan and black grouse. Journal of Wildlife Management 48: 1197-1205.

The authors removed Hooded Crows (Corvus corone cornix), Common Ravens (Corvus corax), and Black-billed Magpies (Pica pica) from Willow Ptarmigan (Lagopus lagopus) and Black Grouse (Lyrurus tetrix) nesting habitat. In ptarmigan habitat, the removal of corvids resulted in increased nest success in only one of the four years. Chick mortality, production, and nesting densities did not change in any year. Estimated Black Grouse nest loss was lower, but chick mortality and production were unaffected. Compensatory nest predation, probably by ermines (Mustela erminea), occurred in the absence of corvids. They concluded that corvid removal was not an effective management technique for increasing game bird production.


Parr, R. 1993. Nest predation and numbers of Golden Plovers Pluvialis apricaria and other moorland waders. Bird Study 40: 223-231.

Carrion Crows and Common Gulls (Larus canus) were removed from a moorland in Scotland to test whether the nest predators were responsible for declining European Golden-Plover populations. The removal of crows and gulls had no effect on plover or other breeding shorebird population. An increase in fox predation was noted that compensated for the removal of the avian predators.


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Last updated 01-Oct-01