Colorado Species. 



Broad-tailed Beaver, Castor canadensis frondator. 



Beavers are found in Colorado pretty generally wliere there 

 is sufficient water for their purpose. The food of beavers consists 

 of bark of trees and bushes, for which they usually store a quantity 

 of branches for use in the winter. The only complaint of damage 

 by beavers we have had is from the damming of streams, which 

 often diverts water from irrigating ditches and floods meadows. 



NATURAL ENEMIES OF RODENTS. 



As natural enemies of rodents, hawks and owls ]'ank first, 

 with the weasel, skunk and badger as close seconds. Hawks and 

 owls have long been known by naturalists to be of great economic 

 importance because of their habit of feeding extensively upon 

 rodents injurious to agricultural crops. With the exception of 

 the goshawk, sharp-shinned hawk, and horned owl, these valuable 

 birds are protected by law in most states. 



Notwithstanding these wise laws, hundreds of thousands of 

 these useful birds are annually destroyed by gunners and thought- 

 less farmers, who consider them enemies to game birds and 

 poultry. Goshawks, sharp-shinned hawks and horned owls are 

 not common in Colorado. Our common hawks are marsh hawk, 

 western red-tail hawk, Swainson's hawk, sparrow hawk, and two 

 species of rough-legged hawks. Our common owls are long-eared, 

 short-eared, and Rocky Mountain screech, none of which make a 

 practice of molesting the poultry yard. Of the hawks mentioned 

 above, ranking in order of their economic importance, are Swain- 

 son's, and the marsh hawk. The marsh hawks occasionally eat 

 poultry, Swainson's rarely. Not only is Swainson's hawk of great 

 importance as a destroyer of rodent pests, but it feeds at certain 

 times of the year almost exclusively on grasshoppers. The writer 

 has seen hundreds of these birds, in the fields during fall migra- 

 tion, hopping around, catching grasshoppers. 



Badgers, skunks, weasels, black-fotted ferrets, wildcats and 

 coyotes feed extensively on rodents. 



I have observed weasels a number of times Avorking over the 

 plains and mountain meadows, infested with prairie-dogs, ground- 

 squirrels and gophers, moving soft-footed and stealthy as a phan- 

 tom shadow, investigating every burrow. AVith their slender 

 bodies they can enter very small openings, follow the windings of 

 the burrows, and they are very destructive to the rodent at the end 



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