Home Range of the Western Jumping Mouse, Zapus Princeps, in the Colorado Rocky Mountains Nathaniel Stinson Jr

Great Basin Naturalist

Volume 37 | Number 1 Article 9

3-31-1977 Home range of the western jumping mouse, Zapus princeps, in the Colorado Rocky Mountains Nathaniel Stinson Jr. University of Colorado, Boulder

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Recommended Citation Stinson, Nathaniel Jr. (1977) "Home range of the western jumping mouse, Zapus princeps, in the Colorado Rocky Mountains," Great Basin Naturalist: Vol. 37 : No. 1 , Article 9. Available at: https://scholarsarchive.byu.edu/gbn/vol37/iss1/9

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. HOME RANGE OF THE WESTERN JUMPING MOUSE, ZAPUS PRINCEPS, IN THE COLORADO ROCKY MOUNTAINS

Nathaniel Stinson, Jr.'

Abstract.— Western jumping mice, Zapiis princeps, were live-trapped during the summer of 1975 in an aspen forest in the Front Range of the Colorado Rocky Mountains. Home range sizes were calculated using the exclu-

sive boundary strip method, and it was discovered that males had larger home ranges (298-.3315 m^, x = 1743 m^) than females (680-1275 ni", x = 1041 m'^). Mean range length was 96.5 m for males and 78.5 m for females. Spatial relationships showed that females tended to be more territorial than males, based on the females' higher percentage of exclusive home ranges, greater distance between centers of activity, and more uniform spacing.

Jumping mice (Zapodidae) are widely dis- densis), and bluegrass {Poa spp.) dominated tributed over North America. The two east- the understory. ern species {Zapus hudsoniiis and Napaeoz- The study area consisted of an 8 x 10 opus insignis) have been the subject of grid of trapping stations spaced 10 m apart. considerable research (e.g. Snyder 1924; Three small Sherman live traps were placed Sheldon 1934, 1938a, 1938b; Hamilton at each .station. The study area was sampled 1935; Blair 1940; Quimby 1951; and Whita- for four days twice a month during July, ker 1963a, 1963b). However, ecological lit- August, and September 1975. On capture, erature on the western jumping mouse each individual was sexed, weighed, marked

{Zapus princeps) is sparse. Krutzsch (1954) by toe-clipping, and then released. Location briefly discussed the natural history of Z. of capture for each individual was also re- princeps in the Rocky Mountains, and corded. Brown (1967a, 1970) has provided informa- The exclusive boundary strip method was

tion on its reproductive and .seasonal activi- used to measure home range size. The ex-

ty patterns. Although information is avail- ternal points of capture are connected, and able on habitat selection by Z. princeps the resultant area is considered the home (Brown 1967b, Clark 1971, Armstrong range of the individual. Centers of activity

1972), little is known of their spatial pat- were calculated using Hayne's method terns within a single habitat type. Analysis (1949) and were used to assess nearest of these spatial patterns was the thrust of neighbor distance (Clark and Evans 1954). the present study. Results Materials and Methods A total of 58 individuals was captured The study was conducted in an aspen for- during the summer of 1975 in 5760 trap- est adjacent to the University of Colorado nights, representing an average monthly Mountain Research Station, Nederland, Col- density of 31.0/ha (range 28.0-35.0). This orado, at an elevation of approximately density was extremely high compared to 2900 m. This forest was mesic and willow values obtained by Brown (1970), whose {Salix); monkshood (Aconitum columhia- population densities averaged 3.2/ha over a mnn), cowparsnip {Heracleiim lanatimi), Ca- four-year period. Population numbers were nadian reed grass {Calamagrostis cana- stable on a monthly basis, probably due to

Department of Environmental, Population, and Or(»anismic Biology. University of Colorado, Boulder, Colorado 80309.

87 88 Great Basin Naturalist Vol. 37, No. 1

the high longevity characteristic of Zapits Also, Myers does not describe the habi- (Quinibv 1951, Brown 1970). tat's vegetation structure, which may in- All animals captured five or more times fluence home range size. In the present were used in the calculation of home range study, the aspen forest was very productive, size (N = 37). The average home range size and Kenagy (1973) proposed that in years of of males was 1743 m^ (298-3315 m'-^), and high resource levels animals forage over that of females was 1041 m^ (680-1275 m2). smaller areas since in the smaller areas food

The mean range length (greatest distance is readily available and less energy expendi- between captures) was 96.5 m for males and ture is required for foraging. And O'Farrell 78.5 m for females. These differences be- et al. (1975) point out that home ranges of tween the sexes were highly significant (p Perognathus parvus were affected jointly by < .01, t-test). Brown (1970) obtained mean resource levels and population size; neither range length values twice the present values of these factors acted independently. (210.0 m and 155.0 m respectively), but this The exact reason for the large difference is because the population of Zapus princeps in calculated home range sizes is not that he studied showed an extremely nar- known, but home range size is quite labile row, elongated distribution along a moun- and many factors, both intrinsic (e.g. popu-

tain stream. lation size) and environmental, influence its size.

Discussion The home range size of Zapus princeps is similar to that of the meadow jumping Home Range Size mouse, Z. hudsoyiius, in Minnesota. Quimby Home range, as applied to mammals, has (1951) used the inclusive boundary strip been defined by Burt (1943) as "the area method, where the external points of cap- transversed by the individual in its normal ture are considered centers of rectangles activities of food gathering, mating, and whose boundaries are half the distance to caring for young." Home range values for the next trapping station, to determine Zapus princeps in this study were consid- home range size in Z. hudsonius. To facil- erably lower than those found by Myers itate comparison with the present study, (1969). Myers obtained home range values Quimby's values were reduced 15 percent of 3075 m^ for males and 2350 m^ for fe- (see Stickel 1954); this reduction results in males. There are several possible reasons for home range sizes of 1479 m^ for males and the discrepancy: (1) track- versus trap-re- 1307 m- for females. The similarity in home vealed home ranges, (2) different population range size is not surprising, since Quimby densities, and (3) differences in vegetation (1951) found that the preferred habitat of structure of the habitat. Myers used the Z. hudsonius in Minnesota was willow tracking method of Justice (1961) to mon- thickets—and the understory of the aspen itor animal movements, and the results of forest in the present study was dominated track- versus trap-revealed home ranges do by willows. not seem to be directly comparable. Met- McNab (1963) proposed that "hunters" zgar (1973) found that track-revealed home (carnivores, insectivores, and granivores) re- ranges were larger than trap-revealed home quire a larger home range than "croppers" ranges. (herbivores). The home range size of two Myers captured a total of 25 Zapus prin- other species of rodents {Microtus long- ceps throughout the whole summer on a 1.1 icaudus and M. montanus) found in the hectare plot, whereas in the present study area were calculated using the same meth- the average monthly density was 31.0/hec- od. Zapus princeps is a primary granivore, tare. It has been well documented that with seeds of the graminoids being most im- home range size varies inversely with popu- portant, while members of the genus Micro- lation density (Burt 1943, Getz 1961, Van tus are primary herbivores (Lechleitner 1969, Vleck ' Mazuriewicz 1971, and Maza 1969, Clark 1971). The average home range et al. 1973). of Z. princeps was significantly larger (p < March 1977 Stinson: Western Jumping Mouse

.001, t-test) than that of the microtines nearest neighbor was always the opposite

(Table 1). The rationale for the difference sex. Hanson and Fleharty (1974) believed in home range size is that food resources of this indicated that territorial behavior was hunters show a more dispersed distribution exhibited by both sexes, but there may be than that of croppers, and therefore must an alternative explanation. In some rodent travel farther on foraging trips. species mated pairs often share the same nest or nest in close proximity, and this may Table 1.— Home range size of three species of ro- be the case with Zapus princeps. The fact dents. that the nearest neighbor is of the opposite sex may just be a by-product of this repro- ductive behavior, and not a by-product of Home Range Size Range Length territorial behavior. The distribution of centers of activity Species N Male Female Male Female should approach uniformity if territorial be-

havior is displayed (Getz 1961). Clark and Microtiis Evans (1954) established "R" as the ratio of longicatidus 11 485 m^ 364 m^ 42.0 m .30.5 m Microtus the observed mean distance to nearest montanm 4 283 m^ 25.0 m neighbor to the expected mean distance to Zapiis nearest neighbor in an infinitely large ran- princeps ,37 1741 m^ 1012 m^ 96.5 m 78.5 m dom distribution. R has a finite range, with values indicative of perfectly clumped (0.00), random (1.00), and uniform (2.1491). Territoriality Distributions of Zapus princeps ba.sed on centers of activity showed that both sexes Getz (1961) suggested that territoriality tended towards uniform spacing (R = 1.33 can be inferred from five criteria: (1) per- for males and 1.51 for females). This differ- centage of exclusive (non-overlapping) home ence between the sexes was significant ranges between members of the same sex, (F = 3.455, p < .01). (2) percentage of at least partially exclusive There were no multiple captures of home ranges between members of the same Zapus princeps in the present study. sex, (3) distance between centers of activity, Quimby (1951) indicated that Z. hudsonius (4) distribution of centers of activity, and (5) was a solitary feeder, and multiple captures sex of individuals involved in multiple cap- were rare. The same may be true with Z. tures. In this study 71 percent of the males princeps. had inclusive home ranges, while no females The analysis of spatial relationships .sug- had inclusive home ranges. Both males and gests that males are quite tolerant to each females had home ranges that were partially other (71 percent of home ranges inclusive), exclusive (29 percent and 84 percent re- and that females tend to be more territorial spectively). Sixteen percent of the female than males, based on their higher percent- home ranges were totally exclusive. age of exclusive home ranges, greater dis- Centers of activity were calculated ac- tance between centers of activity, and more cording to the method of Hayne (1949). uniform spacing. The average distance between centers of ac- tivity was 11.1 m for males and 15.3 m for Acknowledgments females. This difference in mean distance between centers of activity was significant The financial support of a National Fel-

(p < .01, t-test). lowship Fund Predoctoral Fellow.ship is ac- Getz (1961) hypothesized that if the .sex knowledged with gratitude. Thanks is ex- ratio of the population is equal and if terri- tended to Dr. Michael Grant, director, and torial behavior is not displayed, then the the staff of the University of Colorado nearest neighbor should be of the same sex Mountain Research Station for use of their at least half the time. In this study, the facilities. Special thanks to Dr. Larry N. 90 Great Basin Naturalist Vol. 37, No. 1

Brown for comments on an earlier draft of Krutzsch, p. H. 1954. North American jumping mice the manuscript. (genus Zapus). Univ. Kansas Publ., Mus. Nat. Hist. 7:349-472. Lechleitner, R. R. 1969. Wild mammals of Colorado. Literature Cited Pruett Publ. Co., Boulder. 254 pp. McNab, B. K. 1963. Bioenergetics and the determina- Armstrong, D. M. 1972. Distribution of mammals in tion of home range size. Amer. Nat. 97:133-139. Colorado. Monogr., Univ. Kansas Mus. Nat. Maza, G. B., N. R. French, and A. P. Aschwanden. Hist. 3:1-415. 1973. Home range dynamics in a population of 54:405-425. Blair, W. F. 1940. Home ranges and populations of heteromyid rodents. J. Mammal. the jumping mouse. Amer. Midi. Nat. 23:244- Mazurkiewicz, M. 1971. Shape, size, and distribution 250. of home ranges of Clethrionomys glareolus Brow.n, L. N. 1967a. Seasonal activity patterns and (Schreber, 1780). Acta Theriol. 16:23-60. breeding of the western jumping mouse {Zapus Metzgar, L. H. 1973. A comparison of trap- and in princeps) in Wyoming. Amer. Midi. Nat. track-revealed home ranges Peromyscus. J. 78:460-470. Mammal. 54:513-515. 1967b. Ecological distribution of mice in the Myers, L. G. 1969. Home range and longevity in Medicine Bow mountains of Wyoming. Ecology Zapus princeps in Colorado. Amer. Midi. Nat. 48:677-680. 82:628-629. R. R. O. 1970. Population dynamics of the western O'Farrell, T. p., J. Olson, Gilbert, and J. jumping mouse {Zapus princeps) during a four- D. Helund. 1975. A population of Great Ba- 51:651-658. sin pocket mice, Perognathus parvus, in the year study. J. Mammal. Burt, W. H. 1943. Territoriality and home range con- shrub-steppe of south-central Washington. Ecol. cepts as applied to mammals. Misc. Publ. Mus. Monogr. 45:1-28. Zool., Univ. Michigan 45:1-58. QuiMBY, D. C. 1951. The life history and ecology of

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