Arizona \ 
Exp. Sta. J 
LIFE HISTORY OF THE KAXGAROO RAT. 
37 
With two kangaroo rats to the acre (1,280 per square mile), there 
would be 64,000 animals on the 50 square miles of the Range Re- 
serve. If each rat stores 4 pounds of grass seeds and crowns and 
other edible forage during the season (and in severe seasons we find 
that more crowns are stored than under ordinary conditions), a total 
of 256,000 pounds, or 128 tons, of edible forage are rendered un- 
available to stock. In dry years it is probable that this amount of 
forage would be of critical importance. Allowing 50 pounds of 
food a day for each steer, the forage destroyed would be sufficient 
to provide for the needs of one steer for 5,120 days, or for the needs 
of 14 steers for one year. On a stock ranch the size of the Range 
Reserve this might mean the difference between success and failure. 
It seems not unlikely, therefore, that during seasons of drought the 
banner-tailed kangaroo rat, where it is abundant on the grazing ranges 
of the Southwest, may be a factor of critical importance in relation to 
forage production and carrying capacity. It must be remembered, 
moreover, that the stored material consists largely of seeds, so that 
this loss is of greater importance than would be the case were it 
ordinary forage. Some of the range grasses of this region found 
in greatest quantity in the stored material depend in large part, 
under certain conditions, upon seed reproduction. Rehabilitation of 
a depleted range after severe drought and consequent close grazing 
and trampling is retarded by the heavy toll of seed taken by the kan- 
garoo rats. 
CONTROL. 
Kangaroo rats may be easily eradicated by the use of the poisoned 
grain used for prairie-dog control by the Biological Survey and the 
University of Arizona Extension Service. This can be obtained by 
application to the State representative of the Biological Survey or 
to the local county agricultural agent, or may be mixed as follows : 
Formula for poisoned bait. — Dissolve 1 ounce of strychnine sulphate in 1^ 
pints of boiling water. Add 1 heaping tablespoonful of gloss starch, previously 
mixed with a little cold water, and boil until a clear paste is formed. Add 1 
ounce of baking soda and stir to a creamy mass. Add i ounce of glycerine and 
i pint of corn sirup and stir thoroughly. Pour over 16 quarts of rolled barley 
and mix well until every grain is evenly coated. Allow to dry before using. 
In bushel quantities use as above directed, 2 ounces of strychnine, 2 ounces 
of soda, 1 ounce of glycerin. ounces of starch, quarts of boiling water, 
and f pint of corn sirup. 
Scatter poison, when the natural food of the kangaroo rat is scarce, on clean 
hard places near the holes, 1 quart to 50 holes. 
If powdered strychnine alkaloid is used, prepare the hot starch paste first. 
Then sift strychnine and baking soda, previously thoroughly mixed, into the 
hot starch paste and stir to a creamy mass. Proceed as in the above direc- 
tions with sirup, glycerin, etc. 
