oles were trapped in the dry but dense meadow of grass and sedge
covering the floor of the canyon (see Plate 1). _Sorex vagrans_ was
trapped in the same places. Four of the females of _M. montanus_ trapped
on September 3, 1956, were pregnant.

Erethizon dorsatum couesi Mearns Porcupine

_Specimens examined._--Total, 2: 69470, old [Female], and 69471,
her young male offspring, both obtained on August 28, 1956, in the
canyon of the Mancos River, 6200 feet, along the western side of
the River.

I saw no other porcupine in the Park.

In 1935, C.W. Quaintance took special notice of porcupines because of
the possibility, then being considered, of their being detrimental to
habitat conditions thought to be favorable to wild turkeys. Porcupines
were suspected of killing ponderosa pine, which occurred in only a few
places, and which was thought to be necessary for wild turkeys.
Porcupines were recorded as follows: one found dead on the road at the
North Rim on March 16; one killed in oak brush along the North Rim; one
killed between April 15 and May 15; oak brush damaged by porcupines in
Soda Canyon below the well; one seen on July 4 on the Poole Canyon
Trail; one seen at the foot of the Mesa on June 26; one seen by Lloyd
White in Moccasin Canyon on June 27; and one seen by Mrs. Sharon Spencer
on July 1 in Prater Canyon. After four months on the Mesa Verde,
Quaintance concluded that there were not so many porcupines as had been
expected and that there were more ponderosa pines than had been
expected.

In 1946, Donald A. Spencer began a study of porcupines on the Mesa Verde
and in 1958 deposited, in the University of Colorado Library, his
results in manuscript form as a dissertation in partial fulfillment of
the requirements for a higher degree ("Porcupine population fluctuations
in past centuries revealed by dendrochronology," 108 numbered and 13
unnumbered pages, 39 figures, and 13 tables). Dendrochronology, or the
dating of trees by studying their rings, is a technique widely used in
the southwest by archeologists, climatologists, and others. Spencer
found that porcupines damage trees in a characteristic manner, and that
damage to a pinyon pine was evident as long as the tree lived. By dating
approximately 2000 scars and plotting the year for each scar, Spencer
observed three peaks since 1865; these were in about 1885, 1905, and
1935. The increase and decrease each time were at about the same rate.