Life History of the Kangaroo Rat Part 7

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 ma.s.s. Proceed as in the above directions with sirup, glycerin, etc.

Use this poison within five days after mixing or retain in air-tight containers.

_Caution._--All poison containers and all utensils used in the preparation of poison should be kept _plainly labeled_ and _out of reach of children_, irresponsible persons, and live stock.

A spoonful of the poisoned grain scattered about the used entrances of a mound is sufficient, and prebaiting is not necessary, as with prairie dogs.

A word of caution should perhaps be offered in connection with control measures. As man has come to occupy a greater portion of the earth's surface, and as he has become more and more the master of his environment, he has inevitably disturbed the relationships of the birds and mammals about him, has upset the balance of nature. If he kills the carnivorous species because of their depredations on game and live stock he must be prepared to cope with the increased hordes of rodents which feed on vegetation and on which the carnivorous animals act as a check.

If he destroys the rodents, he may remove the checks on certain noxious plants or insects. One control measure often necessitates the adoption of another.

This is not to argue against control measures, for if our harmful species were not controlled, agriculture in many sections would be impossible. Control measures, however, should be scientifically founded and applied. The indiscriminate slaughter of supposedly harmful species of birds and mammals in the guise of benefiting agriculture may do far more harm than good. Many of the species which do some harm do far more good. The exact status of each suspected species should be carefully determined through an adequate scientific investigation. If the species is condemned, sound control measures should be thoroughly applied.

In grazing districts or in areas devoted to intensive agriculture the death sentence should probably be pa.s.sed on the banner-tailed kangaroo rat. It should be recalled, however, that this is the largest and one of the handsomest of all its family, and that it is one of the most characteristic and interesting of all the desert fauna; where extensive grazing or agricultural operations are not undertaken, therefore, we feel that the kangaroo rat should be let alone, unless its presence threatens infestation of valuable agricultural or grazing lands.

SUMMARY.

(1) Kangaroo rats may be separated with ease from all other mammals; the long tail and short and weak fore feet separate them from the pocket gophers; the white hip-stripe distinguishes them from the pocket mice.

The decidedly larger size and the white-tipped tail separate _Dipodomys spectabilis spectabilis_ and _D. deserti_ from _D._ _merriami_ and _D.

ordii_. The darker color and vividly contrasted black-and-white tail of _spectabilis_ distinguish it from _deserti_.

(2) _Dipodomys s. spectabilis_ occurs in the open arid country of portions of the Lower and Upper Sonoran Zones of Arizona, New Mexico, Texas, Sonora, and Chihuahua. It lives in harder soil than does _deserti_, and builds more conspicuous mounds.

(3) There is no evidence of intergradation or hybridization between _spectabilis_ and _deserti_.

(4) _Dipodomys s. spectabilis_ is nocturnal; it is gentle, and does not offer to bite when taken in the hand; is silent for the most part; active; somewhat sociable with its fellows, but fights in defense of its food stores; progresses chiefly by leaping; signals by a drumming or tapping on the ground with its hind feet.

(5) The breeding season of _spectabilis_ begins in January and continues into August. Whether more than one litter is raised in a single season is unknown. The number of young in each litter varies from 1 to 3, averaging 2.

(6) _Dipodomys s. spectabilis_ does not hibernate, but provides food stores, mostly seeds, for use during seasons when food would be otherwise unavailable. Storage in each den varies in quant.i.ty from 5 grams (about 1/6 ounce) to 5,750 grams (12.67 pounds). Materials stored include several important forage plants; for example, various species of _Bouteloua_ and _Aristida_, with _B. rothrockii_ (crowfoot grama) the most important. Accessibility and abundance of different plants have much to do with the kinds of storage found.

(7) The dens of _spectabilis_ are the most notable of all kangaroo rat dwelling places. They range from 6 inches to 4 feet in vertical height, and from 5 to 15 feet in diameter. Here the kangaroo rat has its home, shelter, and food-storage chambers. Within the den is found a tortuous network of burrows, with many storage and some nest chambers, the whole arranged so as to be two to four stories high.

(8) _Dipodomys s. spectabilis_ is not of great economic significance, except locally, in ordinary seasons. During periods of extreme drought it may be of critical importance on grazing areas from the standpoint of the carrying capacity of the range.

(9) Kangaroo rats are easy to poison by following the same formula as that used by the Biological Survey for destroying prairie dogs.

(10) In many places unsuited to extensive grazing or agriculture _spectabilis_ does no appreciable damage. It is one of the most interesting of all the rodents peculiar to our Southwestern deserts, and should not be molested except where it is destructive.

BIBLIOGRAPHY.

ALLEN, J. A.

1895. On a collection of mammals from Arizona and Mexico, made by Mr.

W. W. Price, with field notes by the collector. Bull. Amer. Mus. Nat.

Hist., vol. 7, art. 6, pp. 193-258. 17 figs. in text.

BABc.o.c.k, S. M.

1912. Metabolic water: Its production and role in vital phenomena.

Research Bull. No. 22, Univ. Wisconsin Agr. Exp. Station, pp. 159 and 170, March.

BAILEY, V.

1905. Biological survey of Texas. North Amer. Fauna No. 25, Biol. Surv., U. S. Dept. Agr., pp. 222, 16 pls., 24 figs. in text.

CLEMENTS, F. E.

1905. Research methods in ecology. Lincoln, Univ. Pub. Co., pp. xvii, 334, 85 figs. in text.

GRIFFITHS, D.

1910. A protected stock range in Arizona. Bull. No. 177, Bur. Plant Ind., U. S. Dept. Agr., pp. 28, 6 pls., 1 fig. in text.

GRINNELL, JOSEPH.

1921. Revised list of the species in the genus _Dipodomys_. Journal of Mammalogy, vol. 2, No. 2, pp. 94-97, May 2.

MCATEE, W. L.

1921. Farm help from the birds. In Yearbook of the U. S. Dept. Agr. for 1920, pp. 253-270; unnumbered figs. in text.

MERRIAM, C. H.

1890. Description of three new kangaroo rats, with remarks on the ident.i.ty of _Dipodomys ordii_ of Woodhouse. In North Amer. Fauna No. 4, Div. Ornith. and Mamm. (Biol. Surv.), U. S. Dept. Agr., 41-49.

NELSON, E. W.

1918. Smaller mammals of North America. Nat. Geog. Mag., vol. 33, No. 5, pp. 371-493; numerous unnumbered figs. and colored pls. in text.