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from the woods and nearly eliminated the bird's breeding habitat. 

 Today, wildlife managers and foresters are using prescribed burning in 

 special refuge areas to maintain jackpines at their most attractive stage 

 of growth for the warblers. 



The ivory-billed woodpecker needs large areas of old-growth forests, 

 with their dead and dying trees. Forests of this kind are disappearing 

 because of the accelerating demand for agricultural and timber products. 

 The black-footed ferret, never an abundant species, was unthinkingly 

 reduced to an endangered status by the widespread poisoning of its 

 primary prey, the prairie dog. 



Most predatory birds and mammals have been persecuted for cen- 

 turies because of their threat — real or imagined — to livestock, poultry, 

 fish and game. Now, when predators are more widely appreciated, new 

 threats have arisen to plague these interesting animals. Persistent pes- 

 ticides, notably DDT and related substances, are absorbed from the 

 water in the tissues of fish and other aquatic animals. As larger birds 

 feed on fish and small animals low on the food chain, the contaminants 

 concentrate in their tissues. The result is greatly reduced nesting success 

 by larger fish-eating and predatory birds. The rapid decline of the bald 

 eagle, peregrine falcon, and brown pelican is attributable primarily to 

 pesticides. 



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