OCTOBER 1989 - City of Boulder

Thomomy s talpoides
Distribution.-The northern pocket gopher is a mammal of western
North America, ranging from New Hexico northward to central Canada.
Mostly it occurs in mountainous areas; other kinds of pocket gophers
occupy adjacent valleys and plains. However, the northern pocket
gopher occurs away from the mountains in Boulder County, at Rocky Flats,
for example, and near Eldorado Springs. Sign of these animals is
abundant in suitable habitat throughout the study area,
Description.-These are relatively small pocket gophers, being
adapted to rough upland soils. In our area, the animals are dark in
color, deep brown washed with blackish; often there are small white
spots about the head. The tail is nearly naked, brownish to silvery
. gray. With their short ears, short tail, external fur-lined cheek pouches,
tiny eyes, and fossorial habit, these animals can be confused with no
other local mammals except plains pocket gophers, which are larger in
size and occupy mostly irrigated agricultural lands on the plains.
Mean (and extreme) external measurements of 25 males, followed by
those of 2.l females, all from northern Larimer County, are: total
length, 226.9 (211-244), 228.7 (210-255); length of tai1,6ge6 (58-79),
68.3 (60-83) ; length of hindfoot, 28.7 (27-31) , 28.7 (26-31) ; length of
ear, about 7 mm; weights range from 110 to 150 gr.; condylobasal length
of those animals was 39.62 (37.1-42.2), 38.32 (36.7-40.7) ; zygomatic .
breadth was 23.72 (21.7-25.1), 22.91 (21.4-24.5).
Iiatutal History. -Northern pocket gophers are strongly fossorial, .
coming to the surface only rarely to forage. Mostly, they meet all of
their needs below ground, feeding on roots and tubers of a wide variety
of plants, including forbs, grasses, and shrubs. Burrow systems may be
150 to 200 m in length, with several entrances (actually exits for excess
soil) which typically are plugged. The burrow system may represent the
movement of three tom of soil. Side tunnels are used as storerooms or
latrines. The animals are active year round and evidence of their winter
activity is in the form of ridges of earth ("gopher eskers") festooning
the vegetation of mountain meadows and woodlands. Those ribbons of soil
actually represent the contents of tunnels in snow. The tunnels are
filled with excess soil and as the snow melts, the eskers are left behind.
Pocket gophers may be serious pests on rangelands or about irrigated
fields, because their burrows can injure livestock or damage dit chworks .
However, they are very important agents in the soil-forming process,
aerating the soil and mixing it vith organic matter.
~red~tors of pocket gophers include badge&, snakes, coyotes, and
weasels. Owls take a few pocket gophers as well, particularly young
that ape dispexsbg abwe grot;md, The breeding season is in ~prif or
May and three to 10 (mean four to six) young are born after a
gestation period of about 19 days.
Selected References.-fHnsen (1960) ; Hansen and Ward (1966).
D.M.A.