The food habits of the animal to be controlled are then 
studied,’ and those foods that appear to be preferred and that will 
mix well with the poison are used. One exception is made where a 
choice:of baits is possible, especially when grain is used, and that 
is to select the one least lixely to be taken by birds. There are 
cases, for example, where wheat could be used to advantage, but steam 
crushed oats are employed because they are less likely to be eaten by 
birds. 
After the bait is selected, the quantity that the animal will 
take at one time is ascertained. The bait is then treated with the 
poison to be used and the quantity of this poisoned bait that the 
animal will eat at one feeding is learned. Then the quantity of 
poison that is required to kill the heaviest adult of the particular 
species of animal involved is combined with the quantity of bait that 
the animal will readily eat. In this way the strength of the poisoned- 
bait material is determined for each of the rodents and the carnivores. 
Along with the factors mentioned there are several others that 
have considerable influence upon the building up of a formula. With 
a toxic agent, like strychnine, that is very bitter and has other warn- 
ing features, it is necessary to use chemicals to delay detection by 
the animals. This calls for a long series of experiments to find 
the vest chemical for the purpose and the proper proportion to be used. 
After a formula has been developed, it is then given extensive 
tests in the field, where not only its effectiveness in killing the 
particular animal is studied but also the possibility of killing 
innocent species of wildlife. When poisoned grain is being tested, 
a careful search is made over the treated area to learn whether any 
birds are being killed and, if so, what kinds and how many. This is 
checked at different seasons. If it is found that birds are killed 
at one season but not during others, the time of operations is adjust— 
ed accordingly. Attention is given also to the location of the bait 
spots, so that the poisoned baits will be most readily taken by the 
rodents and least likely to be eaten by birds. 
Protecting Innocent Species 
In the case of coyote poison operations, the definite station 
method of exposure was adopted for several reasons. First, by using 
the whole or a part of a carcass as a lure for coyotes, a station 
could be placed at a distance from stock or wild-animal trails and 
only a few, if any, of the smaller carnivorous animals would find it. 
Secondly, by locating the station away from creek bottoms, where skunks 
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