sign in sign up
<<
Home , Book Cliffs, Callospermophilus, Otospermophilus, Rock squirrel, Wyoming ground squirrel

CIRCULAR 44 NoVEMBER, 1924

THE GROUND OF

BY w. L. BURNETT

OFFICE OF STATE ENTOMOLOGIST

COLORADO AGRICULTURAL COLLEGE

FORT COLLINS, COLORADO OFFICIAL STAFF

C. P. GILLETTE...... ------·------·-·------State Entomologist GEORGE M. LIST ...... ______------···············-----·-··-·--···---·······--···--·-··Chief Deputy R. G. RICHMOND ...... ______Deputy in Charge Apiary Inspection WILLIAM L. BuRNETT ...... Deputy in Charge Control J. H. NEWTON ...... Deputy in Charge Alfalfa Weevil Control W. L. MAY • ...... Deputy in Charge Weed Control WM. P. YETTER, JR ...... Deputy GEORGE ::;. LANGFORD ...... ------··········--··········--············Deputy E. RoBERTS ········································--·········-·······················································-······························Clerk • Deceased

THE GROUND SQUIRRELS OF COLORADO BY W. L. BuRNETT Ground squirrels belong to the rodent family Sciuridae. Other members of this family are tree squirrels, , prairie dogs and woodchucks. Colorado ground squirrels are divided into four genera, Citellus, with five members; , two; Ammospermophilus, one, and , one. On account of the economic importance of this group of to the State, it is necessary that we have as full a knowledge of the habits of its members as possible, for without this knowledge, we are unable to suggest the best methods for its control or to. distinguish the differences between the injurious and the beneficial ones. The object of this circular is to acquaint the general public with the different of ground squirrels that occur in the State, that they may have a better understanding of the problems they have to contend with, from time to time, in ground~ control. Ground squirrels feed extensively on injurious weed seeds and, som.e forms, on insects. During the past few years, from all parts of the country, the cry has gone up to exterminate this, and exterminate that, from predacious mammals to certain birds and . The word '' exter:tninate'' is being used in a reckless and malicious· manner. It is true that it may become necessary to reduce to a minimum certain forms of life for crop and livestock protection, but we should stop far short of extermination, and use control measures only when necessary. Outside of the Wyoming , the· problem of squirrel injury and control is purely a local one. The other species do very little damage to crops, with the exception of the striped ground squirrel in eastern Colorado, which destroys ·newly planted corn,. but, in all sections of the State, its food consists largely of weed seeds, grasshoppers and insect pests. In 1920 we issued Circular No. 30 as Part 1, ''A Contribution to the Lif.e History of the in Colorado.'' In place of issuing Part 2, we have deemed it advisable to publish what additional information we have on this squirrel in this circular, and in­ corporate several paragraphs from Circular 30. We have also added three or four paragraphs on the striped ground squirrel from Circular No. 14, issued from this office in October, 1914. In 1910 Warren published his "Mammals of Colorado. n In 1911 the U. S. Department of Agriculture, Bureau of Biological Sur­ vey, published N. A. Fauna No. 33, ''A Biological Survey of Colo­ rado," by Oary. In the preparation of this circular, both these pub­ lications have been freely consulted and when the name of either Warren or Cary is used in the text, it refers to these respective publi:. cations. 4 GRouND SQuiRRELs oF CoLORADO

ACKNOWLEDGMENTS The writer wishes· to offer the following acknowledgments : To Dr. C. P. Gillette, State Entomologist, under whose directions and guidance he has worked; to Mr. C. L. Corkins, former Deputy State Entomologist, and Mr. S. C. McCampbell a vocational student, he is especially indebted for assistance in field work.

\VYOMING GROUND SQUIRREL C'itellus elegans (Kennicott) DESCRIPTION-From Warren's "Mammals of Colorado." "(From a speci­ men taken in Basin, Routt County, July, 2d.) Upper parts brown, with indistinct mottled or spotted appearance caused by the tip of the hairs being black; in some lights the animal seems to be transversely crossed by narrow, irregular, wavy, black lines; top of head like back, but without the spotted appearance; sides, flanks, and upper surface of feet pale fulvous; underparts (except chin) a somewhat paler shade of fulvous; chin whitish; light, whitish-buff ring around eye; tail above mixed brown and black, tip black edged with whitish; below brown or fulvous, about like sides, with black tip. "Measurements-Total length 10.8; tail vert., 3.0; hind foot, 1.75." The Wyoming ground squirrel is one of the best-known mammals in the sections of the State where it occurs. There is always bustle and activity around its home, as the few short months in summer that it is out of hibernation is none too long for the work to be done in the rearrangement of burrows, breeding and rearing of the young, and the accumulation of fat on its body, that is necessary to keep it alive throughout the long winter months of inactivity. The Wyoming ground squirrel may be distinguished from other ground squirrels of the State by its large size, and short tail. It ~s the largest member of the Citellus group found in the State, and .Is only exceeded in size by the , which has a long tail, and does not belong to the Citellus group. It was first described by Kennicott, under the name of elegans, in the Proceed­ ings of the Academy of Natural Science of Philadelphia in 1863, from a specimen collected by C. D. Drexler, at Fort Bridges, Uinta County, Wyoming. Its distribution is restricted to Colorado, Wyoming and . DISTRIBUTION IN Cm.JORADO--Upper Sonoran, Transition and Canadian Zonest and occurs in all or portions of Weld, Larimer, Jack­ son, Routt, Moffat, Rio Blanco, Garfield, Grand, Summit, Clear Creek, Eagle, Pitkin, Park and Lake counties. East of the Continental Divide the Wyoming ground squirrel reaches the height of its abundance in the Transition Zone ; west of the.Divide it is more common in the Upper Sonoran. East of. the Divide it only occurs in the upper Sonoran Zone in northern Larimer and northwestern Weld counties. t For zone map of ColQrado see N. A. Fauna No. 33. CIRCULAR 44 STATE ENTOMOLOGIST 5

In 1893, Bailey, in writing of Richardson's spermophile, gives the distribution of elegans as follows : "Its southern subspecies, the Wyoming spermophile (Sphermophilus r. elegans), extends over the sage plains of Wyoming from Cheyenne and Laramie mountain westward to Idaho. It is also found in northern Utah and at Fish Creek in the extreme northern part of Colorado."* At the time Bailey wrote this- bulletin, the generic name for the ground squirrel was Spermophilus, and elegans was classed as a sub­ Rpecies of richardsoni. As very little mammalogical work had been done in Qolorado prior to 1893, the Fish Creek record as given by Bailey was not a true status of its- distribution in the State. We have authentic accounts of its not being uncommon in North Park and Western Routt (now Moffat) County in 1883. The writer first met with this squirrel in 1900 on Panhandle Creek near Black Mountain, and on Lone Pine Creek near Manhattan, I1arimer County, Colorado. It seems to have been a native of Wyo­ ming and no doubt entered Colorado on the north from that state. We are not familiar with the distribution of this squirrel in Utah, but in Colorado, from our observations, it is not common west of Range 100 West. In the years we have had this squirrel under observation, its tendency has been to migrate southward, rather rapidly in the past few years. During this time the eastward movement has been slight. We attribute this lack of eastward movement to environmental con­ ditions and altitude, with altitude the dominating factor. A wide variation in altitude causes a corresponding variation in temperature and, if we follow Merriam's theory and see in temperature the chief factor in outlining the life zones of plants and , we find that 0. elegans adheres very closely to the 6000 feet elevation which is sup­ posed to be the lowest which it inhabits in the different zones where found. It is- true that in the Upper Sonoran Zone, in a few localities, it occurs at an elevation considerably lower than 6000 feet, £or example, at Rang.eley in Rio Blanca County and Carr in Weld County. However, to the best of our knowledge it occurs only sparingly at these two points. In Larimer County, at least, there are no natural barriers to pre­ vent the spread eastward to the fertile valley of the Poudre. The line of demarcation is well illustrated in this county in what is known as the Upper Livermore Valley. Squirrels have been common in this locality for twenty yearS' or more. In traveling west from Fort Collins to this section, one could always tell where to expect to run into squirrel territory. Some four or five years ago 0. elegans invaded the plains regions of northeastern Larimer and northwestern Weld Counties. This in­ vasion of the plains also seemingly came from Wyoming and was- not the result of an eastward migration from the older infested region to the westward. * (Page 60, Bulletin No. 4, U. S. D. A., Division' of Ornithology and Mammalogy). 6 GROUND SQUIRRELS oF CoLORADO

BREEDING-Forty-four gravid females examined during the breed­ ing season, in three different years, gave an average of 6.6· young in a litter. Our opinion is that, if the breeding data covered a period of ten years, the average would be considerably higher. One season the number of embryos varied from six to eleven ; one season they varied from six to ten, and one season from one to six, and all three seasons data were from the same locality. We are unable to offer an expla­ nation why the number of embryos was practically the same for two seasons, and so much smaller the third seas·on. Only one litter is raised in a season. Some ranchmen contend that there are two as they have seen immature squirrels early in the season when they are first out of hibernation. This last statement is true as undeveloped individuals are common at that time. Our ex­ planation of this is that in examining gravid females we find embryos varying considerably in development on the same date, so there is much difference in the size of embryos on the same date early in the sea~on. Records we have show that some of the litters are born as late as the middle of June. The following is copied from Circular 30 (Burnett) :- A female of the Wyoming ground squirrel captured May 4, 1920, gave birth to six young on May 19. From the condition of other females taken on the same date in same-locality, we would judge that the period of gestation is about the same as in the Columbian ground squirrel. The young of the caged female were born hairless, blind and toothles~ and measured 60 mm. from tip of nose to tip of tail; their individual weight was five scruples. When born they were of a red­ dish color but, five days later, they were growing rapidly and turni~g dark. On June 1 they weighed fifteen scruples each and fine hmr was starting on back and head, more on head than back, head large and out of proportion to the body. On June 11 their eyes were open, and on the 16th they were crawling around in the nest. Four of the young died within a day or two of each other at this time, seemin~ly from lack of nourishment. June 23 the remaining two were runnmg about the cage for the first time, also on this date they would whistle !ike the mother squirrel when being handled. By June 28 the upper incisor teeth were just beginning to show, lower incisors were one­ fourth inch i.P. length, slender and sharp as a needle. There were no signs of molar or premolar teeth. If the development of caged young is any criterion, they would not be out of their nest before the middle of July, and would not have time to fully develop before they went into hibernation. The following quotation is from Warren's ''~ of. Colo­ rado,'' page 161 concerning some observations on the hibernatiOn of the striped ground squirrel (Oitellus t. tridecemlineatus) b;y Dr. P.R. Hoy in 1875 and published in Proc. Amer. Assn. Adv. SCI. d "He examine~ a complete torpid spermophile on December 15th a~t found the temperature of the abdominal cavity only 58 degrees; the hea CIRCULAR 44 STATE ENTOMOLOGIST 7 was beating only four times a minute, each beat taking ·about four seconde to complete, there was no sign of respiration, and the circulation was so feeble that hardly any blood issued from an amputated limb.'' If conditions are the same with the Wyoming as with the striped squirrel, and we see no reas·on why they should not b~, then, with the low temperature, development would be retarded and the s·quirrels would probably emerge the next spring in the same condition .rela­ tive to size as when they went into hibernation. It is a question if the females of these late litters breed the fol­ lowing season. Foon :-The food of the Wyoming ground squirrel consists of native grasses, timothy, clover, alfalfa, grains and vegetables, native plants and seeds of same. Stomach examination of these squirrels to determine what they were feeding on is unsatisfactory the same as in other rodents, on account of their grinding their food so fine before it is taken into the stomach. Cheek pouches usually give us the best information. In all the squirrels examined we have failed to find any trace of insect remains. The following seeds have been identified in the stomach or cheek pouches of a number of squirrels taken in different localities throughout their range : Seeds of Chamaerhodos erecta " " Cinquefoil, Potentilla sp. " " Dandelion, T aravacum o!Jecinate " " White Primrose, Anogra sp. " " Plantain, Plantgo lanceolata " " Buffalo grass, Buebilis sp. " " Wild Parsley, Cogswellia sp. " Rabbit brush, Chrysothamnur sp. " " M onolepis nuttalliona " " Sedge, Carex sp. " " Psoralea tenuiflora " " Allocarya sp. " " Mustard, Draba aurea Flowers of arnica, Arnica sp. One of the most puz7.ling finds, in connection with stomach examination, was a male squirrel, two-thirds grown, taken at Vir­ ginia Dale, Larimer County, July 13, 1923. The stomach of this squirrel contained no food but was two-thirds full of sand and gravel. Weight of contents of stomach, 5 grams; size of largest gravel, 4x5 mm. HABIT:-We pitched camp one evening in July, 1923, on Lay Creek, near Lay P. 0., Moffat County. Around the camp were numerous burrows of these squirrels, one within ten feet of the tent. While at supper, the squirrel occupying the burrow nearest the tent ventured out on a foraging expedition. We moved over closer to the burrow and when the squirrel returned a few minutes later and attempted to reach its burrow it was frightened away several times. When approaching its burrow it would sit up every few feet and look us over, flickering its tail up and down its back in a very energetic manner. When it finally reached the burrow it closed the opening with dirt and it was still closed when we retired that night. The next morning it had been opened and the dirt thrown outside. 8 GROUND SQuiRRELs OF CoLoRADO

Mr. McCampbell noted a similar occurence at Alma, Park, County in August of the same year. His notes are as follows: ' "Camp site was selected in the midst of a squirrel town, one corner of the tent missing one burrow about fourteen inches. There were five other burrows within a radius of ten feet of the tent. All these burrows were open when we pitched the tent, but within five minutes, three were closed by dirt being thrown up from within. Two of these were open the next morning, but the one by the corner of the tent was not open when we broke camp at 2:00 p. m." We have never noted this occurrence before and we question if these squirrels have a habit of closing their burrowS' for protection against their enemies. We are inclined to believe this is unusual. Like all animals, these squirrels fight among themselves. \Ve have observed a number of these fights, but one that took place one morning in May, 1920, on a grassy hillside near Log Cabin, r.. arimer County, will remain vividly with us. The combatants clinched, rolled over and over, up and down, until exhausted, then lay on their backs or bellies until rested, then continued the fight. ThiS' was kept up until one of the contestants was shot, which proved to be a pregnant female. When fighting they made no sound. A Wyoming ground squirrel and a cottontail rabbit '\Vere seen playing together early one morning along the road near Walden, Jackson County. The rabbit would chase the squirrel awhile, then the squirrel would chase the rabbit. From all appearances they both enjoyed it. Starting about the middle of June and continuing some four or :five weeks, elegans is often seen carrying miscellaneous material such as dry grass, pieces of twine, etc., to its burrows. One was seen on the Laramie River carrying about a fourth of a paper pie-plate; another in Jackson County, was seen carrying a piece of dry horse­ dung. The time of year would indicate that this was in prepartion for hibernating nests. NATURAL ENEMIES :-The Wyoming ground s·quirrel has a num­ ber, of enemies, hawks and owls, altho owls are not common in the State within the range of this squirrel. , badgers and ·weasels are their worst mammalian enemies. A weasel was seen in ~Jackson County carrying an adult squirrel in its mouth acros'S the road. The weight of the squirrel must h.ave been considerably more than that of the weasel, yet it was carried, seemingly, without effort. If the following observation is a guide, the squirrels do not seem to fear the weasels. On Bennett Creek, Larimer County, a weasel was seen playing around a rock pile at the edge of a colo~Y of Citellus elegans. The squirrelS' seemed to pay no attention .to ~t. One squirrel sat up and whistled within 10 feet of the rock p1le m plain sight of the weasel. GENERAL REMARKS :-The daily activity of the Wyoming ground squirrel is largely governed by seasonal and climatic conditions. In CIRCULAR 44 STATE ENTOMOLOGIST 9 the spring, during the breeding season, it is active from sunrise to sun.set. After the breeding season is over and the temperature, is high during the middle of the day, even in the higher altitudes, the daily activity is confined almost wholly to the early morning and late afternoon hours. The voice of the Wyoming ground squirrel is a whistle which, once heard, cannot be mistaken for any other animal by a close ob­ server. When the squrirel whistles it opens its mouth wide and shakes all over from the effort. It whistles when in a horizontal or perpendicular position. It occasionally makes another sound, which resembles very much the chirrup of a cricket, and is entirely different from its well known whistle. The sound is made with only a slight shake of the head. We are inclined to think that this is a warning sound of danger. Accurate data on the spring emergence of the Wyoming ground squirrel from hibernation are not obtainable. From what data we have, climatic conditions seemingly are not an important factor in the control of its appearance in the spring. It has been reported out of hibernation from two localities in Larimer County on March 30, from Eagle County March 25, and from Moffat County February 13, all the same year. Mr. Keefe of Granby, Grand County, states it is out at Granby about April15. We have reports from different localities and we have observed it a number of times where it came up through a foot or two of snow. In our work with the Wyoming ground squirrel, studying its food habits, we have been unable to discover any evidence that it eats insects. However, we have evidence that it feeds to some extent on flesh. W.e have observed it feeding on the dead of its own kind that had been poisoned. A caged female killed and ate her cage mate, a , and two of her own young that died. In Circular 30 from this office the writer stated that ''Albinism is found to some extent among these squirrels. In the spring of 1919 we received from Mr. J. C. Hale two young about two-thirds grown, both of which were white, with the exception of the dorsal parts, which showed a trace of gray, giving them a mottled appear­ ance as found in the normal pelage. These squirrels were taken on the ranch of Mr. B. F. Butler near Steamboat Springs, and the entire litter were albinos.'' THE STRIPED GROUND SQUIRREL Citellus tridecemlineatus pallidus (Allen) DESCRIPTION-From Warrens "Mammals of Colorado." "Striped above six light and seven dark longitudinal stripes; the light stripes a yellowish gray color, some at least of the hairs black tipped; dark stripes a dark brown almost black sometimes; all these stripes except outer one on each side hav~ a row of spots in center of same color as light stripes; outer dark stripe unspotted and ill defined, tt;y of head irregularly marked with colors of back· flanks somewhat rusty; buffy rings around eye; sides and upper surface of feet and under parts similar color to light stripes but somewhat lighter and 10 GROUND SQUIRRELS oF CoLORADO more yellow~sh; chin whitish; tail above indistinctly banded black and yellowish white,, latter color on tips of hairs, and on tip of tail; under sur­ face ,of tail the same color as under part of body ;•

, STRIPED GROUND SQUIRREL ( 0itelltt8 t. 'J)allidus). From a specimen taken at Ft. Collins, in May. Original. M. A. Palmer, Delineator. Original in Circular No. 25

MEASUREMENTs-Average of 20 specimens in Colorado Agricul­ tural College collection total length, 10.00; tail vertebrae, 3.25; hind foot, 1.25. In our series of specimens there is considerable variation in color, some specimens being darker than others. This does not seem to be due to seasonable changes as· spring and fall specimens show the same variations. DISTRIBUTION-From records we have in the office of the State Entomologist, the striped ground squirrel occurs over the entire eastern part of the State, extending, in places, into the hills to an elevation of 7200 feet in Larimer County. Warren (Mammals of Colorado) records it from South Park, Twin Lake and near Lead­ ville. Cary (N. A. Fauna No. 33) reports it from North Park, Huer· fano Valley, and near La Veta. GENERAL REMARKs--The food of the striped ground squirrel con· sists of grains. grasses, weed seeds, insects, etc. The following is from Circular No. 14 (Burnett) from this office, p. 10. ''A striped ground squirrel which we captured alive and kept in a cage at the College museum for several months would eat all kinds of grain, dry bread, cake and meat, and had a great liking for mice, which it would catch, kill and eat with great eagerness. The caged squirrel was very fond of grasshoppers and, no matter what kind of food was in the cage, he would leave everything else for grasshoppers, and would eat nothing else until the supply was exhausted. We placed the grasshoppers in the cage alive, and the squirrel would catch and eat them, sitting up on his hind legs in the characteristic po~e of ground squirrels while feeding. He would seize them with hiS fore feet, bite off their heads, and begin feeding at the head. The CIRCULAR 44 STATE ENTOMOLOGIST 11 legs and wings were bitten off and dropped to the bottom of the cage. Large sphinx larvae were also eaten in the same manner, with great relish. ''These squirrels have been reported as a nuisance from the fact that they dig up seed beans and peas. The one we had refused to eat both dried beans and peas. It is pos'Sible that the squirrels eat them whe~ they are dug up at planting time after the seed has germinated. ''The squirrel is also fond of ground beetles (Oarabidae), a family of predacious insects very common in the State. The caged animal referred to above, refused to eat blister beetles ( M eloidae) . These beetles are used for making blister plasters, the one most commonly used being a European one known as Spanish fly. No doubt these beetles are ill-tasting. ''From an eco~omic standpoint, the striped ground squirrel presents a problem that is somewhat difficult to solve. In some sec­ tions of the State it is no doubt very injurious to corn and newly planted seeds of various kinds, while, on the other hand, in other sections it is beneficial by the destruction of grasshoppers and other injurious insects, cutworms, etc. This is especially true throughout the irrigated districts, where in former years grasshoppers have been such a scourge. From our observations, the striped ground squirrel p!!efers grasshoppers to any other food, and where these insects are abundant it will eat them almost to the exclusion of all other foods. Just where to draw an arbitrary line between the evil and the good is a difficult matter.'' This fondness for insects, especially grasshoppers and lepidop­ terous larvae, was first reported by C. P. Gillette in Bulletin 6, p. 240, of the Iowa Experiment Station, 1889. Professor George E. Johnson, in the Quarterly Journal of the University of North Dakota, Vol. VII, No. 3. April1917, comment;:; on the drinking habits of the eastern form of the striped ground squirrel ( Oitellus tridecemlineatus tridecemlineatus) as follows: "It has been a question whether ground squirrels ever drink water, or depend upon succulent foods for water they need. Two ground squirrels kept under observation were found to go to a tumbler of water in their cage, place the fore feet upon the edge of the glass and drink. As they did so, they moved the lower jaw up and down, producing a sound somewhat similar to that of a cat lapping milk. They repeated this behavior several times. Captive animals always ate water-containing foods such as grass, apples, baked potatoes, and stewed prunes, with great relish. It appears that the animals will drink water when they have access to it, but that when they are a great distance from water they must depend upon vegetation after rains and dews." In the fall of 1923, Mr. S. C. McCampbell captured a young, striped ground squirrel near Julesburg, in the dry-land section of the State, where there is no surface water. The squirrel was about two-thirds grown, was brought to the College and placed in a large wire cage where it soon became tame and allowed itself to be freely handled. It was fed on corn, oats and green alfalfa. Water was 12 GROUND SQuiRRELS OF CoLORADO placed in the cage in a shallow tin. The squirrel made no attempt to drink but licked the outside edge of the lid where a few drops of water had collected. An old gunny sack was placed in the cage and the s-quirrel soon made a snug nest and, in due time, proceeded to go into hibernation, although the room where the cage was located was steam heated. The squirrel came out of hibernation February 15. Water was again placed in the cage and the same performance was repeated as mentioned before. We then took a corn husk and saturated it with water. The squirrel licked it dry. This would suggest that, in so far as drinking is concerned, its parental ancestors were ad­ herents to the Volstead Act, and secured the moisture needed from rains and dews that collected on the plants. The young are born the latter part of May or the :first part of June and number from 8 to 13 at a litter. The average for 13 females-, taken over a period of several years, is 10.1.

SMALL STRIPED GROUND SQUIRREL Citellus tridecemlineatus parvus (Allen) DESCRIPTION-From Warren's "Mammals of Colorado". "Marked and colored like the preceding, though in specimens in the Warren collection the markings do not seem to be quite so sharp.'' "Total length 8.Q; tail vert., 3.0; hind foot, 1.12." Drs'l'RIBUTION-We have specimens from near Lay, Moffat County, and from the Culebra River south of San Acacio, Costilla County. 'Varren (Mammals of Colorado) reports it from Western Routt (now l\-foffat), Rio Blanco, and Garfield counties, and the San Luis Valley. Cary (N. A. Fauna No. 33) gives the distribution covering practically the same territory as Warren and remarks aS' follows: "Nothing is known of the distribution of 0. parvus in the region between the White River Plateau and the San Luis Valley aside from a specimen in the U. S. National Museum labeled 'Elk Mts.' collected by Capt. Stevenson, Sept. 6, 1873.'' On page 91 of the above-mentioned publication, Cary, in hi~ distributional map of the two members of the Citellus trideceml't­ neatus group in Colorado, gives the location of , in northern Gunnison County. Warren spent a number of years in this vicinity and failed to record even seeing a specimen of parmtS in that locality. After a period of :fifty years- with no new records for this section of the State, and knowing the habitat of parvus in the two localities where it has been under our observation, we are inclined to question the authenticity of the Stevenson record, in so far as locality is concerned. C. parvus is- uncommon in Moffat County. In the San Luis Val­ ley, at least in the San Acacio district, it is as common as pallidus is with us in the northern part of the State. The San Acacio specimens CIRCULAR 44 STATE ENTOMOLOGIST 13 average larger than the type specimen and are considerably lighter in color than the specimens we have from Moffat County. It is a comparatively easy matter to s-eparate the specimens from the two localities by external characters. I am not a systematist, therefore not in a position to even suggest separating the two groups. I will, however, venture the prediction that when the revision of the Cit ell us is written, the San Luis Valley squirrels will be separated from true parvus.

SPOTTED GROUND SQUIRREI. (Oitellus obsoletus). From a specimen taken at Wolf Creek, Elbert County, in ApriL Original. M.A. Palmer, Delineator. Original in Circular No. 25

KENNICOT'S SPERMOPHILE Citellus obsolet1.ts (Kennicott) DESCRIPTION,__,_(After Bailey, ''Bulletin No. 4, '' Division of Ornithology and Mammalogy, U. S. D. A.). "This is an obscurely marked, dull-colored little spermophile, with ears hardly perceptible, and short, slender tail. The lower parts are white or soiled whitish, the sides yellowish white. "The back is a~hy gray, usually covered irregularly with obscure spots of whitish, bordered posteriorly by black." "The following measurements are those of an average-sized specimen selected from :fifteen adults: Total length from end of nose to end of tail vertebrae, 222 millimeters (8% inches); length of tail from base to tip of vertebrae, 62 millimeters (2% inches); hind foot, heel to tip of claw, 32 millimeters (1% inches)." The distribution of Kennicott 's ground squirrel in Colorado has not been well worked out. Warren records it from Wray, Yuma County; Sterling, Logan County; and Greeley, Weld County. We have specimens from Kersey, Weld County; JuleS'burg, Sedgwick, County; north-central Elbert County, and west-central Crowley County. One specimen from Crowley County approaches the d~scription of C. s. major, but two more specim.ens from the same locality are identical with two specimens from Sedgwick County. The specimens in the collection show considerable variation in color markings. 14 GROUND SQUIRRELS OF COLORADO

From our observations, 1\:ennicott 's ground squirrels are usually, but not always, associated with kangaroo rats. We have onlv met with one exception, in Elbert County, where two specimens were taken in traps set for the striped ground squirrel, which were very common, and specimens taken only a few feet away from the spot where Kennicott 's were taken. We do not mean to infer that these two rodents are dependent on each other for their existence, but that both prefer the same type of arenaceous soil. The ground squirrels find the ,abandoned or unused burrows of the rats ideal for homes. The locality where we secured our Crowley County specimens was a series of sand dunes covering a considerable area. These dunes were honeycombed with rat burrows and their runways, or paths, radiated in all directions. The Weld County specimens were taken where the Aeolian sand was piled high along the fences, and was, likewise, inhabited with kangaroo rats. The Sedgwick County specimens were taken in traps set for kangaroo rats along a ditch bank and the traps yielded both species of rodents. Bailey has the following to say about the young of this squirrel : "We may infer that the young are born and cared for in the burrows until old enough to be safely trusted above ground. They seem to be brought forth later than the young of most spermophiles. On June 20, 1888, I caught two females, each containing eight young that would not have been born for some time!' (Bulletin No. 4, Division of Ornithology and Mammalogy, U. S. D. A.) July 30, 1924, Mr. S. C. McCampbell captured seven young of this squirrel near Kersey, Weld County, by digging them out of an old kangaroo-rat burrow, after seeing one playing around the opening. These young were a little over one-half grown, and, from their state of development, they could have only been out of their nest a day or two. This would fix their date of birth the first week in July. In the young the spots and light rings around the eyes were very prominent, also the ears which showed black inside. Along the sides were long, gray hairs which gave them a very shaggy appearance. They also sat up and whistled in true squirrel fashion. When they arrived at the Museum, they were in a very weakened condition, but a feed of condensed milk from a pipette soon put them in condition to sit up and take nourishment, which consisted mainly of grasshoppers. They would pass up all other kinds of foods for these insects. When grasshoppers were placed in the cage, as long as they were quiet, they were safe. The young squirrels seem­ ingly had no sense of smell, and were unable to locate the hoppers while they were not moving, but at the least movement, the squirrels would pounce on them like a cat on a mouse. No matter in what position the hoppers were caught, the squirrels would turn them .so they could commence eating on the head, then on down the body, (lis­ carding the wings and legs. Various kinds of grass, oats and r:fe were put in the cage, but the seeds of the Wild Millet, Setaria vipidM, were their favorite. CIRCULAR 44 STATE ENTOMOLOGIST 15

LARGE SPOTTED SPERMOPHILE Citellus spilsoma major (Merriam) DESCRIPTION-From Warren's ''Mammals of Colorado'' (From a specimen taken at Monon, Baca County, April 30): "Above, cinnamon brown, with indistinct whitish spots with black pos­ terior edged, the spots extending forward nearly to the shoulders; white ring around eye; upper surface of feet yellowish white; below white; upper surface of tail like the back, white tipped, below paler, with much white. "MEASUREMENTs-Total length, 8.75: Tail vert., 2.35, hind foot, 1.4." We have never taken a specimen of this ground squirrel and know nothing as to its distribution in the State, except the distribu­ tion given by Warren and Cary We quote Warren as follows: "Its range in Colorado is· not very well worked out; it is found near Pueblo, where it seems to be the common species of spermophile, and is found thence east to the Kansas line. Just how far north it goes I do not know. One has been taken near Denver. I have taken it at Lamar, Prowers County, and at Monon, Baca County." Cary writes as follows : "Spotted ground squirrels from the Arkansas Valley and southward though not typical are referred to this form. Specimens from Las Animas and La Junta (18 miles south) in th~ Biological Survey Collection agree in size with typical major from Albuquerque, New Mexico,. but are grayer." ROCK SQUIRREL Otospe'rrnophilus gram.rnurus grarnmurus (Say) DESCRIPTION-From Warren's "Mammals of Colora.do" (From a specimen taken at Colorado Springs, Sept. 13th). "Upper surface of animal, except head, presenting a mottled or dappled appearance; this is due to the fact that the basal half of the hairs is black, and the other part either gray or rusty rufous, with black tips; the rufous area extends along .back from behind shoulders to and out into the tail a short distance; the flanks and upper surface of feet are rufous, latter rather pale; the sides and neck light' gray, top of head grizzled rufous; light ring around eye; chin and throat rusty, rest of under surface of body mixed whitish and rusty. "The tail is quite full and .bushy, and except the basal two inches is mixed gray and black both above and below, the black rather predominating above and the gray below; on the basal two inches the gray replaced ·by the rufous; the individual hairs of the tail are banded; about one-half of: base iight; then one-quarter inch black, then one-quarter inch light, one-auarter inch black; one-quarter inch light tip. Examined separately these light portions are white, or practically so, but in combination with the black portions produce the gray effect. «

W.e have records of its occurrence in the State as follows: Alford, Bellevue, and Masonville in Larimer County ; Evergreen, Jefferson County; Franktown, Douglas County ; Howard, Cotopaxi and Texas Creek, Fremont County; Goodpasture and Rye, Pueblo County; Walsenburg, Huerfano County; Trinidad, Las Animas County; Lib­ erty, Red Mesa and Durango, La Plata County; Placerville, San Miguel County; Redvale, Montrose County; Delta, Cory, Cedaredge, Hotchkiss and Paonia, Delta County; Clifton, Grand Junction and Fruita, Mesa County; Rifle, New Castle, Glenwood Springs arid Car­ bondale, Garfield County; Salida and Buena Vista, Chaffee County. Warren has tak.en specimens in El Paso, Montezuma and Baca Coun­ ties, and reports it from Saguache County (Mammals of Colorado). This squirrel has a vertical distribution in the State between 4500 and 7000 feet elevation. However, at an elevation of 6000 feet is where it reaches the height of its abundance. GENERAL REMARKs-The rock squirrel inhabits the rocky hillsides and is seldom found very far away from these rupicoline associations. In some localities on. the western slope there is a slight deviation in its home life. This is well illustrated in lV(esa County between the Book Cliffs and Grand Junction, where a number of deep, dry washes occur several miles from the hills. In this situation grammurus makes its home in burrows in the ground along the edges of these washes. The rock squirrel is the only ground squirrel in Colorado that climbs trees. In the northern part of its range on the eastern slope it feeds on the seeds .of various wild plants, and the seeds of the thorrrapple ( Crataegtts sp.) and, when available, grain and the pits of the cultivated cherry. Of the grains, corn is its favorite. We shot one at Spring Canon, Larimer County, that had been feeding on the blossoms of the Yucca (Yucca glauca). Farther south on this slope the acorns of the oak (Quercus sp.) are available and of these it is very fond. Throughout its range on the western slope grammttrus finds cul­ tivated fruits to its liking and feeds on apples, apricots, and cherries to the extent of causing the fruit growers considerable loss. SAY'S GROUND SQUIRREL Callospermophiltts lateralis lateralis (Say) DESCRIPTION-From Warren's ''Mammals of Colorado'' (From a specimen taken May 19, near Sheephorn Pass, Grand County, Colo­ rado): "Back between stripes, nape, and top of head a mixture of black, grayish white, and rufous; inner pair of stripes black, not very well defined; light stripes yellowish, rusty white, extending from shoulder to hip, outer dark stripe black, quite wide and well defined; flanks and sides of neck deep bright chestnut; upper surface of feet a pale, yellowish, rusty color; a light ring around eye; below, light rufous, black bases of hairs showing through: upper surface of tail mixed black' and chestnut, rather ill-defined, black border, with chestnut outside that again. In warm winter and early spring pelages, the colors are grayer, and the black stripes are often quite rusty. A July specimen has top of head chestnut. CIRCULAR 44 STATE ENTOMOLOGIST 17

Callospermophilus lateralis lateralis. Rabbit Ear Pass, Jackson Co., Colo., Sept. 7, 1921. Photo by C. L. Corkins.

"MEASUREMENTS-Total length, 11; tail vert. 3.5; hind foot, 1.65.'' Say's ground squirrel inhabits all the mountain counties of the State and reaches the height of its abundance between 7000 and 9000 feet elevation. It occurs from these elevations up to and above 10,000 feet, and down to 5,500 feet. Say's ground squirrel is the most strikingly colored of all the ground squirrels that occur in the State. Whenever seen it immedi­ ately commands attention by its bright colors and prominent side stripes. Its burrows are usually under rocks or fallen logs, S'eldom in the open. If in the open, they are never far away from the rock and log association. Its home is almost wholly confined to the forest covered hills. You may see it running over logs or rocks, carrying its tail usually curved over the back, or lying fiat on its belly watching you from some advantageous point. These points are usually on top of a rock that overlooks a considerable area. It is sure footed and no rock pile is seemingly too high for it to climb. I have never seen it attempt to climb a tree. However, I observed one at Virginia Dale, Larimer County,_ up three feet in a false raspberry (Bossekia deliciosa) bush, feeding on the ripe berries. Callo cheek pouches are well developed to carry large quantities of grain or other foods to the storehouse beneath the ground. One of these squirrels under observation on the upper Poudre, Larimer County, was busy carrying oats, waste grain, from a freighter's feed bags. It made a number of trips from the oat pile to its burrow with its cheek pouches distended like a well.developed case of mumps. When storing oats in pouches, it lay fiat on its belly, and did not as­ sume an upright position, as is common with other ground squirrels. It also carried small pieces of bread we threw out, but these were carried in its mouth, not in cheek pouches. 18 GROUND SQUIRRELS OF CoLORADo

Another specimen at the same place was seen feeding on the seeds of the dandelion (Taraxacum sp.). This s·eems to be a favorite food with the ground-inhabiting species of the Sciuridae family, as we have observed chipmunks and Citellus elegans feeding on the leaves, blos­ soms and seeds of this plant. Say's ground squirrels around the camps eat various scraps from the camp fare, including meat and cheese. We have very little data on the hibernation of this squirrel. From what we have, our opinion is that its period of activity is of longer duration than that of Cit"elltts elegans, with which it is more closely associated than with any other ground squirrel we have in the State. One of these squirrels accidentally caught in a mouse trap set for Peromyscus squealed like a young pig in the same predicament. This is the only sound I have heard them make, except an angry chuckle when two are having an argument over a choice bit of food.

WORTMAN'S GROUND SQUIRREL Callospermophilus wortmani (Allen) TYPE LOCALITY-Kinney Ranch, Bitter Creek, Sweetwater County, Wyoming. DESCRIPTION-From Warren's "Mammals of Colorado": "From a specimen in fresh pelage taken on Snake River, Routt County (now Moffat) (June 21). A paler animal than the preceding, but the pat· tern of coloration is exactly the same. The rufous and chestnut are much paler, while the inner black dorsal stripe is but faintly indicated, almost obsolete; the outer dark stripe is much less black, and the light stripe is much whiter; the chestnut 0f the flanks, shoulders, and sides of neck, though bright, is of a much lighter shade, upper surfaces of feet paler, almost white, below the animal is white in comparison with lateralis; in the upper surface of the tail the chestnut is a little more prominent, and below it is much paler. "Measurements-As in lateralis. "Distribution-At present 'Vortman's Ground Squirrel seems to be known from the type locality, and from western Routt (now Moffat) County, Colo· rado. In our state it is an inhabitant of the arid region of the Snake River Valley, where . I took it on the west slope of Cross Mountain, about eig~t miles above Lily P~ 0., ::).nd also three miles farther up the Snake; I found 1t at Douglass Springs, in the Escalante Hills."

ANTELOPE SQUIRREL Ammospermophilus leucurus C'innammrwus (Merriam) DESCRIPTION-From Warren ''Mammals of Colorado'' : "(From a specimen taken at Grand Junction October 3.) ~ack grizzled, black, white, and rufous, top of head rufous, . very little black intermixed; a distinct white stripe on either side of back, abo.ut on~ eighth Of an inch Wide, extending from shoulder to hip; shoulders, SideS O body below stripe and flanks, and upper surface of feet, a light rufous or oinnaxpon color light ring ~bout eye, under surface of body white, upper hsty· ~ace of tail black, white edged under surface white, mixed black and w 1 e border and· tip. "Measurements...... Total length, 8.50; tail vert., 2.50; hind foot, 1.60." CIRCULAR 44 STATE ENTOMOLOGIST 19

DISTRIBUTION-We have only met with this squirrel a few times and only in Mesa County near Palisade. Warren gives the distribu­ tion in the State as follows: "An inhabitant of the Lower Sonoran and .lower portion of the Upper Sonoran Zones, it is found in the less elevated districts of southwestern Colo· ra.do, from Grand Junction up the Gunnison to Hotchkiss, and presumably it is found up the Grand River some distance." It has been met with near Montrose, near Coventry, Montrose County, 6,800 feet, and at Bedrock, in the same county; also in west­ ern Montezuma County.'' Cary reports it as follows: "The is. found in the warm desert areas of western and southwestern Colorado below 6,000 feet, chiefiy in the valleys of the streams tributary to the Colorado and Green Rivers. There are specimens at hand from White River, 20 miles east of Rangely; Fruita, Grand Junction; Hotchkiss; Coventry, 6,400 feet; and Ashbaugh's ranch, near McElmo. "The northward dispersion is limited by the Yampa Plateau, between White and Bear Rivers!'