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UNIVERSITY OF KANSAS PUBLICATIONS
MUSEUM OF NATURAL HISTORY


Volume 14, No. 6, pp. 99-110, 1 fig.

December 29, 1961




Natural History of the Brush Mouse
(Peromyscus boylii) in Kansas
With Description of a New Subspecies

BY

CHARLES A. LONG


UNIVERSITY OF KANSAS
LAWRENCE
1961


UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Theodore H. Eaton, Jr.

Volume 14, No. 6, pp. 99-110, 1 fig.
Published December 29, 1961


UNIVERSITY OF KANSAS
Lawrence, Kansas


PRINTED BY
JEAN M. NEIBARGER, STATE PRINTER
TOPEKA, KANSAS
1961

[Illustration]

28-8518




Natural History of the Brush Mouse (Peromyscus boylii) in Kansas With
Description of a New Subspecies

BY

CHARLES A. LONG


In order to determine the geographic distribution of the brush mouse in
the state, 15 localities, chosen on the basis of suitable habitat, were
investigated by means of snap-trapping in the winter and spring of 1959,
spring of 1960, and winter and spring of 1961. Variation in specimens
obtained by me and in other specimens in the Museum of Natural History,
The University of Kansas, was analyzed. Captive mice from Cherokee
County, Kansas, were observed almost daily from March 27, 1960, to June
1, 1961. Captive mice from Chautauqua and Cowley counties were studied
briefly. Contents of 38 stomachs of brush mice were analyzed, and
diet-preferences of the captive mice were studied. Data from
live-trapping and from snap-trapping are combined and provide some
knowledge of size and fluctuation of populations in the species.

Examination of the accumulated specimens and the captive mice reveals
the occurrence in southern Kansas of an unnamed subspecies, which may be
named and described as follows:

     #Peromyscus boylii cansensis# new subspecies

     _Type._--Male, adult, skin and skull; No. 81830, K. U.; from 4
     mi. E Sedan, Chautauqua County, Kansas; obtained on December
     30, 1959, by C. A. Long, original No. 456.

     _Range._--Known from 3 mi. W Cedar Vale, _in_ Cowley County,
     Kansas, and from the type locality.

     _Diagnosis._--Size medium (see Table 1 beyond); underparts
     white; upper parts Ochraceous-Tawny laterally, becoming
     intermixed with black and approaching Mummy Brown dorsally
     (capitalized color terms after Ridgway, 1912); eye
     nonprotuberant; tail short but well-haired distally and
     usually less than half total length; nasals long; cranium
     large.

_Comparisons._--From _P. b. attwateri_, the subspecies geographically
nearest _cansensis_, the latter can be easily distinguished by the less
protuberant eyes and relatively shorter tail (91 per cent of length of
head and body; in topotypes of _P. b. attwateri_ from Kerr County,
Texas, 104 per cent; in specimens of _P. b. attwateri_ from Cherokee
County, Kansas, 103 per cent). _P. b. cansensis_ is darker than _P. b.
attwateri_ and darker than _P. b. rowleyi_, the palest subspecies of
brush mouse, which occurs to the westward. The skull and nasals (see
Table 1) in adults of _P. b. attwateri_ from Cherokee County average
shorter than in _cansensis_.

     _Specimens examined._--Total, 26. _Cowley Co._: 3 mi. W Cedar
     Vale, 16. _Chautauqua Co._: type locality, 10.

TABLE 1. AVERAGE AND EXTREME MEASUREMENTS OF SPECIMENS OF P. B.
CANSENSIS, OF P. B. ATTWATERI FROM CHEROKEE COUNTY, KANSAS, AND OF
TOPOTYPES OF P. B. ATTWATERI LISTED BY OSGOOD, 1909.

======================================================================
               |       _P. b. cansensis_        |  _P. b. attwateri_
               +-----------+---------+----------+---------+-----------
               |Three miles|  Type   |   Both   |Two miles|   Type
               |  west of  |locality |localities|south of |locality[A]
               |Cedar Vale |         |          | Galena  |
---------------+-----------+---------+----------+---------+-----------
No. specimens  |    11     |    7    |    18    |   20    |    10
               |           |         |          |         |
Total length   |   180.5   |  176.7  |  179.1   |  186.2  |   196.0
               |  170-199  | 166-188 |  .....   | 170-210 |   .....
               |           |         |          |         |
Tail-vertebrae |    85.5   |   85.0  |   85.3   |   94.5  |   100.0
               |   72-101  |  75-93  |  .....   |  83-104 |   .....
               |           |         |          |         |
Hind foot      |    23.1   |   23.6  |   23.3   |   23.8  |    21.0
               |   22-24   |  22-25  |  .....   |  22-25  |   .....
               |           |         |          |         |
Ear from notch |    18.2   |   19.1  |   18.5   |   18.4  |   .....
               |   17-19   |  18-21  |  .....   |  14-21  |   .....
               |           |         |          |         |
Greatest length|    27.9   |   28.3  |   28.1   |   27.8  |   .....
of skull       | 26.8-29.0 |27.9-28.9|  .....   |26.6-29.1|   .....
               |           |         |          |         |
Length of      |    10.4   |   10.2  |   10.3   |   9.9   |   .....
nasals         |  9.9-10.8 | 9.5-10.7|  .....   | 9.1-10.4|   .....
               |           |         |          |         |
Zygomatic      |    14.3   |   13.5  |   13.9   |   13.8  |   .....
breadth        | 13.9-15.0 |13.0-13.9|  .....   |13.3-14.4|   .....
---------------+-----------+---------+----------+---------+-----------

[Footnote A: From Turtle Creek, Kerr County, Texas, after Osgood
(1909:148).]


_Distribution of Peromyscus boylii in Kansas_

The subspecies _Peromyscus boylii attwateri_ is known in the state only
from Cherokee County, the southeasternmost county in the state. Probably
the only locality where the brush mouse occurs in that county is on the
systems of cliffs along Shoal Creek, southward from Galena, to the
eastward of Baxter Springs. This is the extent of the known range, and
in my opinion the probable range, of _P. b. attwateri_ in the state (see
Fig. 1). Cockrum (1952:fig. 49) by mistake mapped the species from west
of Baxter Springs in Cherokee County.

Osgood (1909:149) recorded the subspecies _P. b. attwateri_ from Cedar
Vale, Chautauqua County, Kansas, but the specimen from there must now be
assigned to _cansensis_ on geographic grounds. Probably the specimen was
not obtained from Cedar Vale itself for the habitat is not suitable
there. Numerous specimens are known from 3 mi. W Cedar Vale, _in_ Cowley
County, Kansas, all of which are assigned to _cansensis_. Osgood's
recorded locality is situated between this locality and the type
locality of _cansensis_, which is 4 mi. E Sedan, Chautauqua County,
Kansas. The distribution of _cansensis_ also is shown in Fig. 1.

[Illustration: FIG. 1. Distribution of the brush mouse in Kansas. The
southernmost row of counties includes from left to right Cowley,
Chautauqua, Montgomery, Labette, and Cherokee. Black dots represent
trapping localities from which brush mice were not obtained. Triangles
represent localities from which brush mice were obtained. The stippled
area contains suitable habitat for the brush mouse, but was not
investigated. The easternmost triangle represents a place 2 mi. S
Galena, Cherokee Co., Kansas, from which _P. b. attwateri_ is known. The
westernmost triangle represents a place 3 mi. W Cedar Vale, _in_ Cowley
Co., Kansas, from which _P. b. cansensis_ is known. The triangle of
intermediate position represents the type locality of _P. b. cansensis_,
a place 4 mi. E Sedan, Chautauqua Co., Kansas. Many of the trapping
localities have been investigated more than once.]

The probable geographic range of _P. boylii_ is based on trapping data
(see Fig. 1). The brush mouse is confined to systems of wooded cliffs in
Kansas. The two subspecies seem to be separated by more than 80 miles of
grasslands. Blair (1959) has postulated that in the northeastern part of
its range _P. b. attwateri_ is represented by disjunct, relict
populations formed by diminishing montane or cool, moist environmental
conditions. He has implied that the critical climatic change occurred
during post-Wisconsin times, and that the isolation of these populations
occurred so recently that no morphological differentiation has resulted
in them. Inasmuch as the species is widely distributed in México, the
southwestern United States, and in California, and has been recorded
from the Pleistocene of California (Hay, 1927:323), it is reasonable to
suppose that the species immigrated into Kansas from the southwest and
that the immigration was in a generally northward or eastward direction.
If long tail and large eyes are specializations for a scansorial mode of
life (discussed below), then _P. b. cansensis_ must be considered more
primitive than _P. b. attwateri_ for the eyes are less protuberant and
the tail is shorter in _P. b. cansensis_ than in the latter. I suggest
that _P. b. cansensis_ occurred in what is now known as Kansas before
_P. b. attwateri_ entered this area by way of the Ozark Mountains. The
occurrence of a mouse of "the _truei_ or _boylei_ group" (Hibbard,
1955:213) in southwestern Kansas in the Jinglebob interglacial fauna of
the Pleistocene adds little to support the thesis outlined above, but is
not inconsistent with the thesis. Incidentally, the geographic
distribution of _P. boylii_ may differ somewhat from that shown by Blair
(1959:fig. 5); whereas he has mapped the distribution of _P. boylii_ to
show disjunctivity in _P. b. attwateri_ and homogeneity in the
distribution of other subspecies of the brush mouse to the westward and
southward, disjunctivity actually occurs frequently also in the western
and southern subspecies.


_Ecology_

In Kansas the brush mouse is confined to systems of cliffs, the faces of
which range in height to at least 40 feet. The highest cliffs--some
approximately 100 feet--on which brush mice are known to occur in Kansas
are along Shoal Creek, Cherokee County. The brush mouse is found on low
bluffs that are parts of higher systems, but in Cherokee County the
mouse was not obtained from low bluffs separated by even a few miles
from the cliff-system along Shoal Creek. As implied above the brush
mouse is adapted for a scansorial mode of life; but other mice and rats
inhabit the rocky crevices of low bluffs. Whereas the brush mouse is
well adapted for living on high cliffs it seems that the other rodents
are better adapted for life on low cliffs. _Sigmodon hispidus_ was
obtained from the low, limestone cliffs mentioned previously. From most
low bluffs in southeastern Kansas (and on some high bluffs outside the
geographic range of _cansensis_) _Peromyscus leucopus_ was obtained. In
Cowley County the brush mouse was abundant when _P. leucopus_ was not
and _vice versa_ during this study. _Sigmodon hispidus_ did not
associate with the brush mouse in any area, although _S. hispidus_ was
often trapped in grassy areas adjacent to cliffs and on the grassy
crests of the hills. Except at the locality in Cherokee County, the pack
rat, _Neotoma floridana_, was found in association with the brush mouse.
_Microtus ochrogaster_ was the must abundant rodent in adjacent
southwestern Missouri (Jackson, 1907) before _Sigmodon_ thoroughly
infiltrated this area and southeastern Kansas. Activities of other
rodents may have confined the brush mouse ecologically to cliffs.
Although the grasslands are a barrier to further intrusion by the brush
mouse into Kansas, one cannot assume that they alone confined the brush
mouse to cliffs. Such an assumption would not explain its absence on
systems of cliffs similar to and near other systems of cliffs on which
it is found in the non-grassy Ozarkian habitats of Arkansas, as was
noticed by Black (1937). Such an assumption would not indicate why the
size of the cliff-systems is correlated with the absence or presence of
the brush mouse on the northeastern margin of its geographic range.

Parasites found on _P. b. attwateri_ include three individuals of the
laelapid mite, _Haemolaelaps glasgowi_. Two of these mites were removed
from a live mouse. Two larval Ixodid ticks, _Ixodes_ possibly _cookei_,
were removed from the pinnae of the ears of a specimen of _cansensis_
from the type locality, 4 mi. E Sedan, Chautauqua County. Four larval
Ixodid ticks, _Dermacentor_ possibly _variabilis_, were removed from the
pinnae of the ears of a live specimen of _cansensis_ from 3 mi. W Cedar
Vale, in Cowley County.

TABLE 2. STOMACH CONTENTS OF 38 BRUSH MICE FROM SOUTHEASTERN KANSAS IN
WINTER AND SPRING.

======================================================
Localities and     |                |     |Acorn|
number of stomachs |      Month     |Empty| pulp|Seeds
-------------------+----------------+-----+-----+-----
2 mi. S Galena     |                |     |     |
  10               | May, 1959      |  2  |  6  |  2
  11               | December, 1959 |  1  | 10  |  0
   3               | March, 1960    |  1  |  2  |  0
                   |                |     |     |
4 mi. E Sedan      |                |     |     |
   3               | December, 1959 |  3  |  0  |  0
   2               | April, 1961    |  1  |  1  |  0
                   |                |     |     |
3 mi. W Cedar Vale |                |     |     |
   6               | December, 1959 |  1  |  3  |  2
   3               | December, 1960 |  0  | 3[B]|  0
-------------------+----------------+-----+-----+-----

[Footnote B: Judged to be acorn pulp or hickory nut pulp.]

Black (1937:195) and Cockrum (1952:180-181) reported stomach contents
of _P. b. attwateri_ from Cherokee County containing acorn pulp, seeds,
and insects. Analysis of 38 stomachs of the brush mouse (Table 2) show
acorns to be the most commonly used food in winter and spring. Seed
coats were only rarely found, and insects were absent. Two captive
females preferred acorns. Live beetles and grasshoppers of numerous
kinds were decapitated and their inner parts eaten. Seeds (wheat, corn,
and oats) were also eaten. Inasmuch as acorns appear to be the chief
food, it is not surprising that the brush mouse is usually found on
cliffs that support stands of blackjack oak (_Quercus marilandica_).
Other oaks are present, but I have no evidence that the brush mouse eats
their acorns. A. Metcalf told me that he observed in December, 1960, a
released brush mouse interrupt its movement toward a hole in a
cliff-face along Cedar Creek, Cowley County, in order to pick up an
acorn (judged to be from the blackjack oak) in daylight. The mouse
carried the acorn into the hole in the cliff. I have observed that
captive brush mice eat acorns of the blackjack oak but not some other
kinds of acorns.


_Behavior_

The chief differences observed between the brush mouse and other species
of the genus _Peromyscus_ in Kansas can be summarized as follows: the
brush mouse is a superior and more cautious climber; seldom jumps from
high places when under stress; is capable of finding its way better in
partial darkness; has a stronger preference for acorns; and sometimes
buries or hides seeds or acorns. These are all behavioral adaptations
that seem in harmony with its mode of life.

Buck, Tolman, and Tolman (1925) showed the balancing function of the
tail in _Mus musculus_. Climbers (for example, squirrels) often possess
long, well-haired tails. It is reasonable to suggest (as did Hall,
1955:134) that the long, tufted tail is an adaptation for a scansorial
existence. Little observation is necessary to observe how such a tail is
used in balancing. Furthermore, it is used as a prop when the mouse is
climbing a vertical surface. Dalquest (1955:144) mentioned tree-climbing
in _P. boylii_ from San Luis Potosí, México. It may occur in _P. b.
attwateri_ or in _P. b. cansensis_ also, but there is no evidence as yet
to prove it.

The brush mouse can seldom be induced to jump from heights of two feet
or more. Rather it tends to scamper downward or to remain in place. It
often swings itself over an edge, holding to it by its hind feet, and
sometimes to it lightly with its tail, and reduces a short jump by
almost the length of its body. Such caution seems to be an adaptation in
a mouse that lives as a climber.

Many animals of cavernous habitats have small eyes (see Dobzhansky,
1951:284). Some nocturnal animals (for example, owls) have large eyes.
The brush mouse has large, protuberant eyes; it lives in the deep
crevices and fissures of the cliffs on which it is found, but it is not
strictly a cave-dwelling animal. Perhaps large eyes aid the brush mouse
in performing activities in the partial darkness of a deep crevice or
hole in a cliff. Brush mice experimentally placed in what appeared to be
total darkness fed, built houses of cotton, and ran and climbed in the
usual manner.

On several occasions the captive brush mice hid surplus seeds and on
other occasions hid acorns by burying them and sometimes by placing them
in a small jar. The mice never carried the surplus food into their
house.

Black (1937:195) has claimed that the brush mouse builds a nest similar
to that of the nest of the pack rat, _Neotoma floridana_. Hall
(1955:134) doubts this to be the case. Dalquest (1953:144) described a
nest of _P. boylii_ from San Luis Potosí as seven inches in diameter,
made of leaves, and found in a hollow tree. Drake (1958:110) noted that
_P. b. rowleyi_ lives in holes and crevices in rocky bluffs in Durango,
México. I have found this to be the case for _P. b. attwateri_, as did
A. Metcalf (unpublished) for _P. b. cansensis_. Nests of sticks and
leaves were taken apart by Metcalf, and all sign indicated only the
presence of the pack rat. I have observed that there are no such houses
on the cliffs along Shoal Creek, Cherokee County, and that no pack rats
have been obtained from there (pack rats have not been reported from
Cherokee County). Blair (1938) found two brush mice (_P. b. attwateri_)
in the house of a pack rat in Oklahoma. Nests of the brush mice that
occur in Kansas have not been found.

A lactating, pregnant female (KU 81833) of _P. b. attwateri_, containing
three embryos, was obtained on December 24, 1959, and shows that this
subspecies breeds in winter. Accumulated records for the subspecies
indicates year-round breeding (see Cockrum, 1952:181). Another female
obtained on March 27, 1960, was probably lactating.

Pregnant females of _P. b. cansensis_ (KU 84892, 84895, and 84890) were
obtained from the type locality on April 1-2, 1961, containing 3, 4,
and 5 embryos respectively. This indicates, perhaps, increased breeding
in spring; five was the highest number of embryos found in brush mice in
Kansas.


_Population Studies_

In the period of my study the populations of brush mice became smaller,
perhaps owing to the severe winter of 1959-1960. In Cowley County, _P.
leucopus_ is now abundant and _P. boylii_ rare where in December of
1959, the opposite was true. It is also possible, of course, that
trapping has depleted the populations.


Conclusions

   1. A new subspecies of brush mouse is named and described from
      southern Kansas.

   2. The new subspecies has smaller eyes and a shorter tail and may
      be more primitive than _P. b. attwateri_.

   3. No significant sexual dimorphism was noted in _P. boylii_.

   4. In Kansas, _P. b. attwateri_ is known only from a single
      locality; _P. b. cansensis_ is known from only two localities,
      both in Kansas.

   5. The cliff-dwelling habit of _P. boylii_ probably isolates
      populations from one another.

   6. The grasslands constitute a barrier for the brush mouse.

   7. In Kansas, _P. b. cansensis_ probably is an older population
      than _P. b. attwateri_.

   8. In Kansas the brush mouse is confined to systems of cliffs
      that are wooded and that are at least 40 feet in height.

   9. The brush mouse may be confined to cliffs in part by
      activities of other rodents.

  10. The brush mouse commonly associates with the pack rat.

  11. Laelapid mites have been found on specimens of _P. b.
      attwateri_.

  12. Larval ixodid ticks were found on specimens of _P. b.
      cansensis_.

  13. Acorns seem to be the chief food of the brush mouse; insects
      and seeds are also commonly eaten.

  14. The brush mouse is adapted for climbing and probably for a
      partly subterranean life.

  15. _P. b. attwateri_ breeds in winter, as well as in other parts
      of the year.

  16. _P. b. cansensis_ is known to breed in early April.

  17. The highest number of embryos obtained from a brush mouse in
      Kansas is five.


Acknowledgments

     I am indebted to Prof. E. Raymond Hall and to Mr. J. Knox
     Jones, Jr., for suggestions and editorial assistance. Prof. R.
     H. Camin identified the ticks and mites recorded herein. Mr.
     A. Metcalf, Mrs. C. F. Long, and Mr. D. L. Long helped with
     the field studies and in other ways.


Literature Cited

BLACK, J. D.

  1937. Mammals of Kansas. 30th Biennial Report, Kansas State
        Board of Agri., 35:116-217.

BLAIR, W. F.

  1938. Ecological relationships of the mammals of the Bird Creek
        Region, Northeastern Oklahoma. Amer. Midl. Nat.,
        20:473-526.

  1959. Distributional patterns of vertebrates in the southern U.
        S. in relationship to past and present environment.
        Zoogeography, pp. 463-464 and Fig. 5, January 16.

BUCK, C. W., TOLMAN, N., and TOLMAN, W.

  1925. The tail as a balancing organ in mice. J. Mamm.,
        6:267-271.

COCKRUM, E. L.

  1952. Mammals of Kansas. Univ. Kansas Publ., Museum of Nat.
        Hist., 7:6, 180-181.

DALQUEST, W. W.

  1953. Mammals of the Mexican state of San Luis Potosí. Louisiana
        State Univ. Studies, Biol. series No. 1, 232 pp.

DOBZHANSKY, T.

  1951. Genetics and the origin of species, 3d ed. New York,
        Columbia Univ. Press, x + 364 pp.

DRAKE, J. D.

  1958. The brush mouse, Peromyscus boylii, in southern Durango.
        Museum Publ., Michigan State Univ., 1:97-132.

HALL, E. R.

  1955. Handbook of mammals of Kansas. Univ. Kansas Mus. Nat.
        Hist. Publ. No. 7, 303 pp.

HAY, O. P.

  1927. The Pleistocene of the western region of N. America ...
        Carnegie Inst. Washington, 346 pp., 12 pls.

HIBBARD, C. W.

  1955. The Jinglebob interglacial (Sangamon?) fauna from Kansas
        ... Museum of Paleo., Univ. Michigan, pp. 179-228, 2 pls.

JACKSON, H. H. T.

  1907. Notes on some mammals of southwestern Missouri. Proc.
        Biol. Soc. Washington, 20:71-74.

OSGOOD, W. H.

  1909. Revision of the mice of the American genus Peromyscus. N.
        Amer. Fauna, 28:1-285, April 17.

RIDGWAY, R.

  1912. Color standards and color nomenclature. Washington, D. C.,
        43 pp., 53 pls.


_Transmitted June 30, 1961._


28-8518