66 



defence.* Fragments of the small- jointed cactus 

 (0. leptocaulis) were also used for the same 

 purpose. Occasionally partly eaten prickly- 

 pear segments were seen close to mounds built 

 around mesquite stumps, and had evidently been 

 brought from a distance by the rat, as ' there 

 were no Opuntias near by. 



Joints are readily devoured in situ, and, 

 as just mentioned, some may be carried a consider- 

 able distance to the "house." The stomach 

 contents of a captured animal appeared to 

 consist entirely of cactus pulp. Some weeds 

 close to a nest were found to have been eaten 

 down by some rodent, presumably a pear rat. 



This animal gnaws into the stems and bases 

 of the plant around which the house is built, 

 often entirely ringbarking them. Sometimes the 

 injury does not extend inwards beyond the 

 woody cylinder, but at other times the branch 

 may be almost or entirely cut through. In spite 

 of the rapidity with which the CactaccEe can 

 form a hard callus to protect an injured surface, 

 it often happens that decay sets in which may 

 lead to the destruction of the entire branch. 

 More usually, however, the branch bends over, 

 allowing the distal parts to reach the ground, 

 where they may strike root, and thus it is quite 

 a common sight to see a cactus clump with the 

 centre entirely destroyed and often containing 

 a conspicuous rat mound, while the surrounding 

 mass really consists of a large number of 

 independent but intermingled plants which 

 have originated in this way. Thus the animal 

 may act as a distributor of prickly-pear. 

 However, many instances were met with where 

 it had been a very efSeient destroyer. It was 

 quite common to see areas near Alice where 

 scarcely an Opuntia remained alive, though the 

 presence of abraded stumps and numerous ' ' nests ' ' 

 told of former activity of these rodents. In this 

 locality, within a radius of about 30 feet one 

 could frequently count nearly twenty such 

 stumps. Though extensive damage was seen at 

 Brownsville, the most marked results were 

 noticed in the more open country which was 

 lightly timbered with mesquite trees — e.g., near 

 Alice and Sinton. 



In order to become fully acquainted with 

 the food habits of the Neotoma, local inquiry 

 was made at each of the Southern Texas towns 

 visited. Some observers referred to the wide- 

 spread destruction of prickly-pear by rats at 

 certain times, the animals migrating in large 

 numbers at intervals of some years. Some Mexi- 

 can farmers stated that they found these rodents 

 occasionally attacking cultivated plants, more 

 especially beans, but that they generally confined 

 themselves to a diet of Opuntia. Another stated 

 that they ate house refuse and also grain such as 

 maize, invading the barns for the latter. Mr. R. 

 E. Moore, a farmer near Sinton, informed the 

 Commission that these pear rats fed on cactus 

 and mesquite, but occasionally entered his barn 

 I'M took away some corn, though they did not do 

 any appreciable damage, nor did they attack his 

 growing crops as far as he knew. They would, 

 however, take cotton bolls, use the seeds, and 



* Certain other wood rats have a similar habit, e.g., 

 Neotoma mexicaruz, Baird, in and about whose nest Dr. 

 Merriam (1890, p. 67) has mentioned that cactus spines 

 are distributed in abundance, no doubt as a protection 

 against coyotes and skunks. 



distribute the cotton on their mounds. He did 

 not think them capable of exterminating the pear, 

 though they greatly injured it. Another farmer, 

 however, was positive tliat they had eaten out the 

 cactus completely from his farm. Another 

 fanner, Mr. J. J. Love (from Alice district), 

 referred to the great destruction of prickly-pear 

 occasioned by the periodical visits of swarms of 

 these animals, whose presence he considered bene- 

 ficial on account of their activity in eliminating 

 Ccictus, though they might take grain or cotton. 



Prof. D. E. Merrill, of the New Mexico 

 Agricultural College at Mesilla Park, referred to 

 the occurrence of an allied species, Neotoma albi- 

 gula, Hartley, known locally as the "pack rat" 

 on account of its habit of constructing a mound 

 resembling that of N. micropus referred to above. 

 This rodent fed on the joints and fruit of both 

 flat and cylindrical Opuntias, and would enter 

 granaries in search of grain, sunflower seeds, &e. 



In company with Prof. J. J. Thornber, of the 

 t^niversity of Arizona, the Commission visited 

 some localities near Tucson, and found that this 

 species, N. alhigula, was not uncommon. Its 

 habits were seen to be similar to those of its 

 Texan relative, though the destruction of prickly- 

 pear was not nearly so great. The stem-joints 

 and fruit of both flat and cylindrical Opuntias 

 were attacked, though the most damage appeared 

 to be occasioned to siieh shrub-like species as 0. 

 amonica. 



Rats, probably belonging to a species of Neo- 

 toma, were seen occasionally amongst clumps of 

 0. occidentalis near San Diego in Southern 

 California. 



Mr. Vernon Bailey, in his "Biological 

 Survey of Texas" (1905), referred to the distri- 

 bution and habits of certain wood rats (Neotoma, 

 spp.) in that State. The nests or mounds of all 

 are, as a rule, similar to that of N. micropus 

 referred to earlier, though some species — e.g., N. 

 alhigula, N. mexicana, and others — prefer to build 

 in gullies and along cliffs. The species and 

 ■^^arieties referred to by IMr. Bailey are — (1) N. 

 floridana rubida, Bangs, (East Texas and Loui- 

 siana) ; (2) N. floridana baileyi, Merriam (North 

 Texas and Oklahoma to North Nebraska) ; (3) 

 N. floridana attwateri, Mearns (West Texas) ; 

 (4) N. micropus, Baird (Western and Central 

 Texas, New Mexico, Oklahoma, and parts of 

 Mexico and South Texas) ; (5) N. albigula, 

 Hartley (West Texas and New Mexico) ; (6) N. 

 mexicana, Baird (Texas). This enumeration 

 does not include all the species of Neotoma 

 occurring in the United States, since Dr. Merriam 

 (1899, p. 94) mentions two wood rats, N. fuscipes 

 and N^ cinerea, as occurring in the northern 

 part of California. The food of the various 

 species mentioned by Bailey consists of acorns, 

 green leaves and berries of various kinds, wild 

 grapes, walnuts, fruits, stems and joints of 

 Cactacese, seeds, nuts, mesquite bean-pods, and 

 grain of any kind.* 



In an interview, Mr. Bailey referred to the 

 diversified character of their food, which in- 

 cluded, in addition to those already mentioned, 

 maize, cotton-seed, pine-nuts, melon-seeds — in 

 fact, any kind of wild or cultivated seed which 



* At least one species, N. drurmnondii, Richardson, 

 lives in the far north-west of Canada and British Columbia, 

 beyond the regions where Caotaceas occur. (Preble, 1908, 

 p. 176.) This species has been removed from the genus 

 Neotoma and made the type of the genus Teonoma Gray 

 (Pahner, 1909, p. 859). 



