Part 12 (1/2)

Individuals of _P. maniculatus_ obtained on the northern end of Wetherill Mesa in May and June of 1962 had numerous ectoparasites. At this time, the population of _P. maniculatus_ was high, but on a downward trend.

My data and observations lead me to conclude that individuals of _P.

maniculatus_ are more heavily parasitized by both botflies and endoparasites than are individuals of _P. truei_. The reasons for this unequal amount of parasitism in two species of mice occurring in the same general area remain obscure.

The kinds of endoparasites and ectoparasites collected from _P.

maniculatus_ and from _P. truei_ are listed below (m = present in _P.

maniculatus_, t = present in _P. truei_).

ACARINA: Ixodidae: _Dermacentor andersoni_ mt, _Ixodes angustus_ mt, _Ixodes spinipalpis_ m. Laelaptidae: _Androlaelaps glasgowi_ m.

Myobiidae: _Blarin.o.bia_ sp. m. Trombiculidae: _Euschoengastia lanei_ mt, _Euschoengastia criceticola_ m, _Euschoengastia dicipiens_ t, _Euschoengastia peromysci_ m, _Leewenhoekia americana_ m, _Trombicula loomisi_ m.

DIPTERA: Cuterebridae: _Cuterebra cyanella_ mt.

SIPHONAPTERA: _Callistopsyllus deuterus_ m, _Catallagia decipiens_ m, _Epetedia stanfordi_ mt, _Malaraeus sinomus_ mt, _Malaraeus telchinum_ mt, _Megarthroglossus procus_ mt, _Monopsyllus wagneri wagneri_ mt, _Orchopeas leucopus_ mt, _Peromyscopsylla hesperomys adelpha_ mt, _Phalacropsylla allos_ t, _Rhadinopsylla sectilis goodi_ t, _Stenistomera macrodactyla_ m, _Stenoponia_ (_ponera_ or _americana_) mt.

CESTODA: _Choanotaenia_ sp. m, _Hymenolepis_ sp. t.

NEMATODA: _Mastophorus numidica_ mt, _Syphacia obvelata_ mt, _Trichuris stansburyi_ t.

ACANTHOCEPHALA: _Moniliformis clarki_ mt.

PREDATION

In order to determine the relative numbers of each species of _Peromyscus_ that were taken on a seasonal basis by predators, scats of coyotes and foxes were collected from trails and roads at least twice each month, from September 1963 through August 1964. Scats were identified, labeled and dried; all bones and samples of hair were later removed from each scat. Scats that were intermediate in size between the droppings of foxes and coyotes, and that could not be identified readily in the field, were not collected. Bones from the scats were identified to species, and hair was identified to genus or species by comparing color patterns or cuticular patterns with samples from known mammals.

More than 200 impression slides and whole mounts of guard hair and underfur were prepared.

Seven individuals of _P. truei_ and three individuals of _P.

maniculatus_ were represented in 114 coyote scats (Table 13). Both species of _Peromyscus_ comprised only 3.9 per cent of the 253 items of food represented in the 114 scats. Rabbits, _Sylvilagus_ sp. and mule deer, _Odocoileus hemionus_ were the major food items of coyotes. Mice of the genus _Peromyscus_ apparently were preyed upon mostly in autumn (September through November), when mouse populations were near their yearly peaks.

Foxes also prey upon _Peromyscus_ in the park. One _P. truei_ was represented in the 16 scats of foxes that were a.n.a.lyzed. This individual was taken in the winter quarter (December through February).

The bobcat may be an important predator upon _Peromyscus_ in this region, but few scats of this animal were found. Since these could not be a.s.signed to a specific month, they were not saved for a.n.a.lysis.

Anderson (1961:58) believed that bobcats and gray foxes were the most abundant predators in the park. My observations over a period of two years led me to conclude that coyotes were more abundant than foxes and that foxes were, in turn, more abundant than bobcats.

TABLE 13--Food Present in 114 Coyote Scats Collected at Mesa Verde National Park each Month from September 1963 through August 1964.

============================+=============+============

Number

Percentage Food Item

of

of total

occurrences

items ----------------------------+-------------+------------ _Sylvilagus_ sp.

32

12.65 _Spermophilus variegatus_

5

1.97 _Eutamias_ sp.

12

4.74 _Reithrodontomys megalotis_

4

1.58 _Peromyscus boylei_

2

0.79 _Peromyscus maniculatus_

3

1.18 _Peromyscus truei_

7

2.76 _Neotoma cinerea_

2

0.79 _Neotoma mexicana_

9

3.56 _Neotoma albigula_

5

1.97 _Neotoma_ sp.

3

1.18 _Microtus longicaudus_

1

0.39 _Microtus mexica.n.u.s_

11

4.34 _Microtus monta.n.u.s_

1

0.39 _Microtus_ sp.

1

0.39 _Odocoileus hemionus_

59

23.32 Gra.s.s

34