BRITISH COLUMBIA: Atlin, 7 (6 CAS; 1 PM); _Deep Creek, 60 mi. above Telegraph Creek_, 1 (USBS); _Sawmill Lake, near Telegraph Creek_, 6 (MVZ); junction 4 mi. N Telegraph Creek, 1 (ROM); McDame Post, Dease River, 1 (USBS); _Stikine River, at Glenora_, 28 (MVZ); _Kispiox Valley, 23 mi. N Hazelton_, 3 (MVZ); _9-mi. Mtn., 4500 ft., NE Hazelton_, 1 (MVZ); Hazelton, 959 ft., 20 (MVZ); Bear River, 7 mi. N Bear Lake, 1 (USBS); Charlie Lake, Fort St. John, 1 (PM); _Moose River_, 2 (PM); Tupper Creek, 7 (PM); _Babine_, 2 (USBS); _Port Simpson_, 3 (USBS); 12 mi. N Summit Lake, Alaska Highway, 3300 ft., 3 (NMC); _Giscome_, 1 (USBS); _Ootsa Lake_, 3 (PM); Inverness, mouth Skeena River, 1 (USBS); W end Eutsuk Lake, 1 (PM); Wapiti, head of Middle Branches River, 1 (USBS); Hagensborg, 15 (NMC); _Stuie, Cariboo Mtn., 4700 ft._, 2 (NMC); Rainbow Mts., Mt. Brilliant, 5000 ft., 10 (NMC); N 7 Wistaria P. O., 13 (NMC); _Mt. McLean, Lillooet_, 1 (PM); Mt. Robson P.
O., Mt. Robson Park, 1 (MVZ); _Indianpoint Lake, 15 mi. NE Barkerville_, 42 (29 MVZ; 18 PM); Cottonwood P. O., 2 (MVZ); Mt. Revelstoke, 3400 ft., 6 (PM); Glacier, 1 (ROM).
YUKON: Rose River, mile 95 on Canol Road, 1 (NMC).
_Marginal records._--Yukon: Rose River, mile 95 on Canol Road, British Columbia; McDame Post, Dease River; Charlie Lake, Fort St. John; Tupper Creek; Wapiti, head of Middle Branches River; Mt. Robson P. O., Mt.
Robson Park; Mt. Revelstoke, 3400 ft.; Cottonwood P. O.; Rainbow Mts., Mt. Brilliant, 5000 ft.; Inverness, mouth Skeena River. Alaska: Taku River. British Columbia: Atlin.
=Zapus princeps utahensis= Hall
_Zapus princeps utahensis_ Hall, Occ. papers, Mus. Zool., Univ.
Michigan, 296:3, November 2, 1934.
_Jaculus Hudsonius_, J. A. Allen, Bull. Ess.e.x Inst., 6:65, April, 1874 (part--the part concerning Great Salt Lake Valley, Utah).
_Zapus princeps princeps_, Wolfe, Jour. Mamm., 91:154, May 9, 1928.
_Zapus princeps idahoensis_, Davis, Recent Mammals of Idaho, Caxton Printers, Caldwell, Idaho, p. 341, April 5, 1939 (part--the part from southeast Idaho).
_Type._--Female, adult, skin and skull; No. 59153, Museum of Zoology, University of Michigan; Beaver Creek, 19 mi. S Manila, Daggett County, Utah; obtained on July 16, 1928, by A. and R. D. Svihla, original No.
176.
_Range._--Southeastern Idaho and extreme western Wyoming (Teton, Snake, and Uinta Mt"s) southward through Uinta, Wasatch, Oquirrh, and Beaver Mt"s of Utah. See fig. 46. Zonal range: Transition, Canadian, and Hudsonian.
_Description._--Size, large; back from Cinnamon-Buff to Warm Buff overlaid with black hairs; sides lighter with less admixture of black hairs; lateral line indistinct, sometimes wanting; tail bicolored, brownish-black above, white to yellowish-white beneath; feet grayish-white above; ventral surface white to base of hairs; ears dark, edged with white to yellowish-white; skull large; palatal bridge relatively short; upper tooth-rows diverging anteriorly; occipitonasal length great; interorbital region broad; zygomata widely bowed; postpalatal notch anterior to posterior face of last molars; mastoid width great.
_Comparisons._--From _Zapus princeps princeps_, _Z. p. utahensis_ differs in: color dorsally and laterally less ochraceous, lacking broad lateral line; skull larger in every part measured, excepting length of palatal bridge and breadth of palate at M3; zygomata more bowed; upper tooth-rows more divergent anteriorly; postpalatal notch anterior to posterior border of last molars.
Compared with _Zapus princeps cinereus_, _Z. p. utahensis_ differs as follows: Size averaging larger; upper parts darker, Cinnamon-Buff not Pinkish-Buff; incisive foramina wider posteriorly; palate wider; zygomata more robust.
For comparison with _Zapus princeps idahoensis_ see account of that subspecies.
_Remarks._--_Zapus princeps utahensis_ most closely resembles the several subspecies in the Great Basin in its large size, widely bowed zygomata, and posteriorly broadened incisive foramina. Intergradation between _Z. p. utahensis_ and _Zapus princeps cinereus_, geographically the nearest of the Great Basin subspecies, is not known. Intergradation in color and cranial characters occurs between _Zapus princeps idahoensis_ and _Z. p. utahensis_ in specimens from 17 mi. E and 4 mi. N of Ashton, Idaho. All these specimens are, however, referable to _Z. p.
idahoensis_. Animals from 9 mi. SE Irwin and from 3 mi. SW Victor, Idaho, resemble _Z. p. utahensis_ in most differential characters (dorsally ochraceous, lateral line more distinct, incisive foramina large, palate broad anteriorly, auditory bullae less inflated), and are here referred to _Z. p. utahensis_. A series of specimens from the head of Crow Creek, Idaho, were considered by Davis (1939:340) to be intergrades between _Z. p. idahoensis_ and _Z. p. utahensis_; he thought that the specimens were more nearly like _Z. p. utahensis_ in color, but cranially (80 per cent in average ratio of anterior width of palate to posterior width of palate), more nearly like _Z. p. idahoensis_, to which subspecies he referred them. I have examined these specimens and find them to be more nearly like _Z. p. utahensis_ not only in color but in cranial characters as well. For example, the average ratio obtained by me for anterior width of palate to posterior width of palate is 72 per cent, rather than 80 per cent as given by Davis (_loc. cit._). Other cranial characters, size of the incisive foramina, shape of the foramen magnum, and shape of the auditory bullae, indicate relationship with _Z.
p. utahensis_ to which they are here referred. Two immature individuals from Strawberry Creek, 20 mi. E Preston, Idaho, considered to be _Z. p.
idahoensis_ by Davis (_op. cit._:341), also are here referred to _Z. p.
utahensis_.
_Specimens examined._--Total, 178, distributed as follows:
IDAHO: _Bonnerville County_: _9 mi. SE Irwin, 6400 ft._, 3. _Caribou Co._: Head Crow Creek, Preuss Mts., 7500 ft., 6 (USBS). _Franklin County_: Strawberry Creek, 20 mi. NE Preston, 6700 ft., 2 (MVZ). _Teton County_: 3 mi. SE Victor, 6 (MVZ).
UTAH: _Beaver County_: Puffer Lake, 1 (UU). _Daggett County_: junction Deep Creek and Carter Creek, 7900 ft., 2 (UU). _d.u.c.h.esne Co._: _Currant Creek, Uinta Forest_, 2 (USBS). _Morgan Co._: _exact locality not given_, 1 (UU). _Rich County_: 12 mi. SW Woodruff, 1 (MVZ). _Salt Lake County_: _Lambs Canyon, 2 mi. above Parleys Canyon, 7000 ft._, 1 (UU); _head Lambs Canyon, 9000 ft._, 3 (UU); _Salamander Lake and Lambs Canyon, 9000 ft._, 11 (UU); _"The Firs," Mill Creek Canyon_, 2 (UU); _Brighton, Silver Lake P. O., 8700 ft., Cottonwood Canyon_, 1 (UU); _Brighton, Big Cottonwood Canyon, 8000 ft._, 1 (UU); _1 mi. above Alta_, 4 (UU); b.u.t.terfield Canyon, approximately 5 mi. above b.u.t.terfield Tunnel, 3 (UU). _Sanpete Co._: _8 mi. E Fairview and 5 mi. S Mammoth R.
S., Manti Nat"l Forest, 9000 ft._, 1 (USBS); _Baldy R. S., Manti Nat"l Forest_, 1 (UU); Ephraim, 8850 ft., 1 (USBS). _Summit County_: _Henrys Fork, Uinta Mts., 8000 ft._, 4 (UU); 14 mi. S and 2 mi. E Robertson, 9300 ft., 3. _Uintah County_: 21 mi. W and 15 mi. N Vernal, 10,050 ft., 1. _Utah County_: Payson Lake, 8300 ft., 12 mi. SE Payson, Mt. Nebo, 12 (UU); _1 mi. E Payson Lake, 8300 ft., Mt. Nebo_, 3 (UU). _Wasatch County_: Provo River, 3 mi. N Soapstone R. S., Wasatch Nat"l Forest, 1 (UU).
WYOMING: _Lincoln County_: 3 mi. N and 11 mi. E Alpine, 5650 ft., 37.
_Teton County_: 1/4 mi. E Moran, 6700 ft., 4; _Bar B. G. Ranch, 6500 ft., 2-1/2 mi. NE Moose_, 11; _Moose, 6225 ft._, 1. _Uinta County_: 2 mi. E Robertson, 7200 ft., 1; _9 mi. S Robertson, 8000 ft._, 21; _9 mi.
S and 2-1/2 mi. E Robertson, 8000 ft._, 1; _9-1/2 mi. S and 1 mi. W Robertson, 8600 ft._, 2; _10 mi. S and 1 mi. W Robertson, 8700 ft._, 18; _10-1/2 mi. S and 2 mi. E Robertson, 8900 ft._, 1; _13 mi. S and 1 mi. E Robertson, 9000 ft._, 4; _5 mi. E Lonetree_, 1 (ROM).
_Marginal records._--Wyoming: 1/4 mi. E Moran, 6700 ft.; 2 mi. E Robertson, 7200 ft. Utah: junction Deep Creek and Carter Creek, 7900 ft.; Paradise Park, 21 mi. W and 15 mi. N Vernal, 10,500 ft.; Ephraim, 8500 ft.; Puffer Lake; Payson Lake, 8300 ft., 12 mi. SE Payson, Mt.
Nebo; b.u.t.terfield Canyon, approximately 5 mi. above b.u.t.terfield Tunnel.
Idaho: Strawberry Creek, 20 mi. NE Preston, 6700 ft.; 3 mi. SW Victor.
=Zapus hudsonius= (Zimmerman)
(Synonymy under subspecies)
_Range._--From Pacific Coast of Alaska eastward to Atlantic Coast; from northern limit of tree-growth south into central Colorado and northeastern parts of Oklahoma and Georgia. See fig. 47.
[Ill.u.s.tration: FIG. 47. Distribution of _Zapus hudsonius_.
Guide to subspecies
1. _Z. h. acadicus_ 6. _Z. h. hudsonius_ 2. _Z. h. alascensis_ 7. _Z. h. intermedius_ 3. _Z. h. america.n.u.s_ 8. _Z. h. ladas_ 4. _Z. h. campestris_ 9. _Z. h. pallidus_ 5. _Z. h. canadensis_ 10. _Z. h. preblei_ 6. _Z. h. hudsonius_ 11. _Z. h. tenellus_]
_Externals._--Size small to medium (total length 188 mm to 216 mm); tail longer than head and body (112 mm to 134 mm) and bicolored, pale brown to brownish-black above, white to yellowish-white below; hind feet long (28 mm to 31 mm), grayish-white above; back ochraceous to dark brown; sides paler than back with dark hair interspersed; lateral line usually present but sometimes indistinct or entirely absent (when present usually clear Ochraceous-Buff); ventral coloration white, sometimes with suffusion of ochraceous; guard hairs average 115 microns (96u to 140u) in diameter; underhair with pigment pattern in form of hollow, narrow rectangles; cuticular scales of underhair large and fewer than those of the underfur of _Z. trinotatus_, but underhair of _Z. hudsonius_ otherwise resembles that of _Z. trinotatus_.
_Baculum._--Size small (total length 4.5 mm to 4.9 mm); base medium in width (0.64 mm to 0.72 mm); tip narrow (0.24 mm to 0.26 mm) and dished out in dorsal aspect, blunted; shaft rounded, curving gently upward at tip.
_Skull._--Small to medium and relatively narrow in relation to length; rostrum pointed and short; mastoid region relatively narrow; incisive foramina short; base of zygomatic process of squamosal narrow; coronoid process of mandible short, relatively weak. Upper premolar usually small (averaging .30 mm in length and .35 mm in breadth) sometimes functional (most often so in old adults), occlusal surface divided by single shallow re-entrant fold, which in worn teeth forms centrally located lake; tooth-row short as compared to that of other species; individual cheek-teeth usually smaller than those of other species; lower cheek-teeth shorter and narrower than those of other species; angle of mandible strongly inflected.
GEOGRAPHIC VARIATION
The species _Z. hudsonius_ is divisible into 11 subspecies based on differences in color, relative proportions of the tail, hind feet, body, and size and shape of parts of the skull (zygomata, braincase, incisive foramina, auditory bullae, pterygoid fossae, rostrum, and interorbital breadth).
Color of the pelage varies, as a general rule, from dark-backed, dull-sided individuals in the northern parts of the geographic range of the species to light-backed, bright-sided individuals in the southern parts of the range.
Individuals from the southernmost geographic races (_Z. h. america.n.u.s_ and _Z. h. pallidus_) are the smallest for the species and those from the northernmost subspecies (_Z. h. alascensis_) are the largest. One subspecies, _Z. h. campestris_, from the central part of the range of the species, however, seems to be out of the cline. This form inhabits the eastern foothills of the Rocky Mountains and is a robust animal approaching _Z. princeps_ in size.
Seemingly there is no clinal variation in the several qualitative features of the cranium, for instance in the shape of the auditory bullae, shape of the incisive foramina, and shape of the postpalatal notch. On the other hand, the dimensions of the entire skull show that the larger crania are of the northernmost subspecies and the smaller of the southernmost subspecies.
NATURAL HISTORY
_Habitat._--_Zapus hudsonius_ occurs in low undergrowth usually of gra.s.ses or forbs or both, in open coniferous forests, deciduous hardwood groves, or in stands of tall shrubs and low trees, but most frequently in open, moist areas.
Quimby (1951:75) notes that jumping mice were more common in the moist lowlands than in the drier uplands. More were in the open type lowlands than in the forested type, and these mice favored habitats normally bordered by small streams affording moist to semi-aquatic living conditions. The reports of Goodwin (1924:255), Christian (1936:416), G.
S. Miller (1899:329), Cory (1912:249), Lyon (1936:277), Stoner (1918:123), and others, although concerning widely different parts of North America, indicate that _Z. hudsonius_ selects habitats in vegetation of like form, even though different a.s.semblages of plant species may be involved.
An average of 11.91 mice per acre was recorded by Quimby (1951:91) from a study plot at Itasca Park, Clearwater County, Minnesota. He gives the monthly population densities per acre for _Z. hudsonius_ at Centerville, Anoka County, Minnesota, as follows: June 2.78, July 3.57, August 3.10, and September 1.81. Blair"s (1940:248) data on bi-monthly population density per acre for _Z. hudsonius_ on the Edwin S. George Reserve, Livingston County, Michigan, are remarkably similar, when adjusted on a monthly basis, to those obtained by Quimby (_loc. cit._). Blair"s (_loc.
cit._) monthly population densities per acre are as follows: June 3.90, July 3.85, August 3.10, and September 2.00. Townsend (1935:90) estimated population densities per acre for _Z. hudsonius_ in central New York state, at 11 to 72 individuals. As Quimby (1951:92) points out, Townsend"s figures are probably too high, as commonly is the case when the moving quadrat technique is used because animals from neighboring areas enter the trapped area to take over the niches made available by their predecessors" removal.
The population of _Z. hudsonius_ may vary considerably from year to year as well as seasonally. Blair (1940:249) found notably fewer jumping mice on the George Reserve in 1938 than in 1939. Quimby (1951:94) found the numbers of _Zapus_ to be highly variable and thought that there was a rapid turnover. Young animals were not caught until July when 25 per cent were either juveniles, young, or subadults; from this time on these age cla.s.ses increased to a high of sixty-one per cent in September.
Quimby (_loc. cit._) found that separating the individuals into their proper age cla.s.ses was more difficult in September, since the young from early litters are adultlike in appearance. His data indicate as he remarked, "That the over-wintering adults are, for the most part, gradually replaced by the young of the year as the summer progresses."
The s.e.xes in _Z. hudsonius_ vary only slightly from a one to one ratio.
Quimby (1951:63) found a s.e.x ratio of 110 females to 100 males and Blair (1940:245) records a s.e.x ratio of 113 males to 100 females. Townsend (1935:42) records a s.e.x ratio in central New York of 155 males to 100 females. Such a wide variation from a one to one ratio suggest that the moving quadrat technique, which Townsend (1935:90) employed in obtaining his data, may be, in some way unknown to me, more selective for the males.