50 BULLETIN 475, U. S. DEPARTMENT OP AGRICULTURE. 



they are wonderfully diligent and expert in searching it out. Many 

 experiments in the direct seeding of hardwoods and conifers have 

 failed because nearly all of the seed was eaten by mice, chip*munks. 

 and other animals. Where tree seed attractive to rodents is to be 

 sown it is necessary, therefore, to consider the systematic poisoning 

 of the area as an essential operation. In numerous experiments con- 

 ducted by the Forest Service, seed spots have been sown and then 

 covered with small portable screens which effectively protected them 

 from rodents and birds. The successful germination in these spots 

 and the absolute failure in similar unprotected spots adjacent showed 

 how important an adverse factor animals, and possibly birds, are in 

 reforestation. 



In the spring of 1910, in cooperation with the "Bureau of Biological 

 Survey, intensive studies of the damage from rodents were conducted 

 at a number of places where direct seeding was in progress, and on 

 many other sowing areas observations were made by forest officers. 

 In nearly every case a different species of animal was found to be the 

 chief cause of damage. There are, of course, a great many species 

 of mice, chipmunks, and ground squirrels, and a number of different 

 kinds of tree squirrels. Each species appears to have distinctive 

 habits, and the food and activities of the same species differ greatly 

 with the time of year. The kind of poison bait and the manner of 

 applying it must therefore be adapted not only to the species of 

 animal to be destroyed, but to its taste and activities at the time the 

 poisoning is done. The latest approved methods of poisoning 

 rodents shown below are those developed by the United States 

 Biological Survey. 



The poison preparation which most nearly meets all requirements 

 is as follows: 



Mix 1 heaping tablespoonful of gloss starch in * teacup of cold water and 

 stir with 1 pint of boiling water to make a thin, clear mucilage. Remove from 

 the stove. Mix together 1 ounce of powdered strychnine (alkaloid) 1 and 1 

 ounce of powdered bicarbonate of soda and stir with the starch to a smooth, 

 creamy mass. Stir in 1 tablespoonful of glycerine, and finally J ounce of sac- 

 charine. Apply to 20 quarts of good clean oats or wheat and mix thoroughly to 

 coat each kernel. 



This poison is effective in destroying chipmunks, kangaroo rats, 

 pocket mice, the smaller species of ground squirrels, and, at times, 

 kills many white-footed mice. 



Oats are generally the most successful bait. On account of the 

 skill of chipmunks in "hulling," wheat is more effective for these 

 animals. Barley, in the proportion of 16 quarts to each ounce of 



1 If strychnine sulphate is used, dissolve in the boiling water before adding the starch ; 

 also dissolve the bicarbonate of soda before adding to the poisoned starch. Care Is 

 necessary that the resulting mixture does not greatly exceed a pint. 



