Seven adults of this woodland inhabitant were trapped along
shrub-covered banks of the spring-fed stream and small impoundment in
Deer Draw of the Slim Buttes (10 mi. S and 5 mi. W Reva). Deciduous
trees grew in the bottom of the draw, but the slopes above supported
ponderosa pine and juniper. No white-footed mice were found along the
generally treeless tributaries of the Moreau and Grand rivers to the
east of Slim Buttes nor were these mice found along the Little Missouri
River or in likely-looking habitat in the North Cave Hills. The _P.
leucopus_ of Deer Draw likely represent, therefore, an isolated segment
of a formerly much more broadly distributed population of white-footed
mice on the Northern Great Plains in post-Wisconsin times. Other such
populations may exist in Slim Buttes and perhaps elsewhere in the
county. _Zapus hudsonius_ and _Microtus pennsylvanicus_ were trapped in
Deer Draw in association with white-footed mice.
Females collected on June 15 and August 7 were lactating and one taken
on June 20 contained six embryos that measured 15. Two males taken on
June 2 had testes that measured 12 and 15. These two males and a
lactating female taken on June 15 still were in winter pelage, whereas a
non-breeding female obtained on June 15 and a male and female (pregnant)
trapped on June 20 were in summer pelage or an advanced stage of molt to
that pelage. A lactating female taken on August 7 was in summer pelage
excepting that what definitely appeared to be new winter pelage was
present on the head, cheeks, and below the ears, and molt was evident
adjacent to these areas.
Selected average (and extreme) measurements of the seven adults from
Deer Draw are: total length, 184.4 (175-199); length of tail, 77.4
(70-88); length of hind foot, 21.1 (20-22); length of ear, 16.7 (16-18);
greatest length of skull, 27.8 (27.0-28.4); zygomatic breadth, 14.6
(14.0-14.9); least interorbital width, 4.1 (4.0-4.3); length of
maxillary toothrow, 4.2 (4.0-4.4). Three males and two non-pregnant
females weighed 34.9, 34.6, 30.5, 32.2, and 31.4 grams, respectively.
~Peromyscus maniculatus nebrascensis~ (Coues, 1877)