Part 5

Fleas, Dactylopsylla ignota (Baker), were found on one individual examined. Molting adults were taken in each month from May through August.

~Perognathus fasciatus fasciatus~ Wied-Neuwied, 1839

Olive-backed Pocket Mouse

Specimens examined (16).--2 mi. N, 5 mi. W Ludlow, 3; 4 mi. S, 7 mi. W Ladner, 9; 10 mi. S, 5 mi. W Reva, 1; 14 mi. S, 4 mi. W Reva, 2; 15 mi. S, 4 mi. W Reva, 1.

This pocket mouse is not uncommon in areas of short grass and sage in Harding County. None of five adult females taken late in June was pregnant or lactating, but three had enlarged mammae indicative of reproductive activity earlier in the spring, to which young of various sizes in our series also attest. Active molt was evident on adults taken on June 19, 26, and 28.

Our specimens are intergrades between Perognathus fasciatus fasciatus and the paler P. f. olivaceogriseus. Average external measurements of seven adults (two males and five females) are: total length, 138.0 (130-150); length of tail, 65.3 (59-74); length of hind foot, 17.1 (15-18.5); length of ear (six specimens only), 6.8 (6-7); weight in grams (five specimens only), 12.9 (11.2-14.6). Selected cranial measurements of the two males and two of the females are, respectively, as follows: occipitonasal length, 24.0, 23.2, 23.5, 22.3; interorbital breadth, 4.9, 5.2, 5.0, 5.0; mastoid breadth, 13.0, 13.1, 12.2, 11.9; length of maxillary toothrow, 3.3, 3.3, 3.1, 3.4.

~Perognathus hispidus paradoxus~ Merriam, 1889

Hispid Pocket Mouse

An adult female, not reproductively active, that was trapped in rather sparsely vegetated rangeland to the southwest of Slim Buttes (14 mi. S and 4 mi. W Reva) on July 19, 1961, is the only specimen of the hispid pocket mouse on record from Harding County. Other species of small mammals taken in the same or adjacent traplines were Perognathus fasciatus, Dipodomys ordii, Reithrodontomys megalotis, Peromyscus maniculatus, and Onychomys leucogaster.

A single individual reported from Wade, Grant Co., North Dakota, by Bailey (1927:123), approximately 100 miles to the northeast, is the only specimen known from a more northerly locality.

~Dipodomys ordii terrosus~ Hoffmester, 1942

Ord's Kangaroo Rat

Specimens examined (13).--NE 1/4 sec. 22, R. 1 E, T. 23 N, 6; 2 mi. N, 5 mi. W Ludlow, 1; 2 mi. S, 11 mi. W Reva, 1; 14 mi. S, 4 mi. W Reva, 4; 15 mi. S, 4 mi. W Reva, 1.

Ord's kangaroo rat is found in sparsely vegetated flatlands throughout Harding County, although it appears to be uncommon except in localized areas of relatively sandy soils. Five of seven specimens taken from June 18 through 24, 1961, were young of the year, as were three of six individuals trapped on May 31, 1968. One adult female (81.1 grams) obtained on May 31 was lactating and had four placental scars, whereas another that weighed 67.2 grams evidenced no recent reproductive activity. An adult male (67.9 grams) taken on May 31 had testes that measured 9; those of a subadult male (46.5 grams) taken on the same date measured only 6.

The two May-taken adult females mentioned above still were completely in winter pelage, but the adult male trapped at the same time was molting. An adult male (57.2 grams) obtained on June 22 had completed molt save for a small patch between the ears and immediately behind the head.

~Castor canadensis missouriensis~ Bailey, 1919

Beaver

Specimens examined (2).--Sec. 22, R. 1 E, T. 20 N, 1; 32 mi. SE Buffalo, 1.

According to local residents, the beaver is common along many of the water courses in the county. One of our two specimens came from a tributary of the Little Missouri River north of Camp Crook and the other was taken from a tributary of the Moreau River in the southeastern part of the county. Robert Kriege of Buffalo reported to us that beaver are not restricted to wooded areas, but frequently inhabit streams and more or less permanent impoundments bordered by grassland. In such places they are said to construct bank dens and eat principally sage and forbs.

Visher (1914:89) reported this species along the Little Missouri River, Boxelder Creek, the forks of Grand River, Bull Creek, and "Devil's Gulch" in the North Cave Hills, and figured (pl. 6) a dam on Rabbit Creek. We have observed evidence of beaver activity along the Little Missouri River southwest of Ladner and along aspen-wooded stream banks in the Short Pine Hills, where in the spring of 1963 abundant sign was found.

~Reithrodontomys megalotis dychei~ J. A. Allen, 1895

Western Harvest Mouse

Specimens examined (27).--NE 1/4 sec. 22, R. 1 E, T. 23 N, 1; 4 mi. S, 7 mi. W Ladner, 3; 2 mi. N, 5 mi. W Ludlow, 7; 1/2 mi. W Reva, 14; 10 mi. S, 5 mi. W Reva, 1; 14 mi. S, 4 mi. W Reva, 1.

The western harvest mouse was taken commonly in stands of tall grasses and forbs, particularly along roadways and fencerows. Occasional individuals were trapped in areas of mixed shrubs and grasses. Four pregnant females taken in late June carried the following number of embryos (crown-rump lengths in parentheses): seven (4), six (5), six (10), five (4). Three adult males taken in the same period had testes that measured 7, 7, and 8, whereas those of two May-taken males measured 12 and 6.

Molt from winter to summer pelage was in progress, from anterior to posterior, on both the dorsum and venter of many May- and June-taken animals. Some individuals had completed molt, or had but a small patch of winter pelage remaining on the rump, as early as the last week in June.

~Reithrodontomys montanus albescens~ Cary, 1903

Plains Harvest Mouse

Specimens examined (3).--2 mi. N, 5 mi. W Ludlow, 2; 1/2 mi. W Reva, 1.