Occurrence and Relative Abundance of Small Mammals Associated With

Home , Symphoricarpos

AN ABSTRACT OF TEE TEES IS OF

Mark Steven Hinschberger for the degree of Master of Science in Fisheries and Wildlife esented on May Li, 1978

Title:OCCURRENCEAND RELATIVEABUNDANCE OFSMALL MAMMALS ASSOCIATED

$ ALONG TEE COLUMBIARIVER

Abstract approved: Redacted for Privacy Dr. E. C} les Meslow

A small mamma]. inventory of occurrence and relative abundance was

conducted in riparian and upland habitats in six segments along the

lower Columbia River from the river mouth to. MeNary Dam (river mile

292) during 19714. and 1975 by removal trapping on standardized

trap lines.

Analysis of variance was used to compare capture per 100 trap-night

indices of abundance of a species or group of species among habitats

within a segment and among segments ci' the study area.

Of the 59 species of small mannials purported to occur near the

Columbia River, 39were encountered.Many ofthespecies not encounter-

ed. occur at elevations higher than the study area or are rare. Although

23 species were captured in standardized. traps, the deer mouse (Peromys-

cus maniculatus) and vagrant shrew (Sorex va'ans.) comprised 814..9 per-

cent of the.total catch.

The deer nouse, the most abundant species, occurred in all 38 habitats except Russian olive (Elaeagnus antifolia) and increased in abundance from west to east.

Insectivores, mainly vagrant srews, were most abundant in the west and. decreased in abundance along the decreasing moisture adient from west to east as did voles (Microtus spp.). Occ.z'rence and Relative Abundance of Small Manin-ials Associated with Ri.r±an and Upland Habitats Along The Columbia River

Mark Steven Hinschberger

A THESIS

submitted to

Oregon State University

in rtial fulfill-rient. of the reauirements for the degree of

Master of Science

Commencement June 1978 APPROVED:

Redacted for Privacy

Associafe Professor 6f'Fjtsheries and Wildlife

in charge of major

Redacted for Privacy

Head of Department of Fisheries and Wildlife

Redacted for Privacy

Dean of Graduate School

Date thesis is presented May Lij,1978

Typed by Mark Steven Hinschberger for Mark Steven Hinschberger TABLE OF CONTTS

Page

I. INTRODUCTION 1

II. STUDY AREA 3 Climate 3 Description of Segments 3 Intensive Sampling Areas 10

III. NETHODS 12 Sampling 12 Index of Abundance 14 Analysis 17

Iv.RULTS AND DISCUSSION 18 Segment 1 18 Segment 2 22 Segment 3 26 Segment 4 29 Segment 5 33 Segment 6 33 Geoaphic Distribution 39

V. LITERATURE CIT 46

VI. APPENDIC 51 LIST OF TA3L

Table Page

1. Small mammals occurring along the Columbia River. Study area segments listed after species represent range according to various authors. Underscoring denotes occurrence during this study. 19

2. Total number of individuals of each mammalian species captured in standardized gmound traps in intensive sampling areas of the Columbia River study area in fall 1974 and spring 1975. 20

3. Mean index of abundance (captures per 100 trap-nights) values of small mammals in habitats inventoried in segment 1 of the Columbia River study area. 21

4. Mean index of abundance (captures per 100 trap-nights) values of small mammals in habitats inventoried in segment 2of the Columbia River study area. 23

5. Mean index of abundance (captures per 100 trap-nights) values of small mammals in habitats inventoried in segment 3 of the Columbia River study area. 27

6. Mean index of abundance (captures per 100 trap-nights) values of small mammals in habitats inventoried in segment 4 of the Columbia River study area. 30

7. Mean index of abundance (captures per 100 trap-nights) values of small mammals in habitats inventoried in segment 5 of the Columbia River study area.

8. Mean index of abundance (captures per 100 trap-nights) values of small mammals in habitats inventoried in segment 6 of the Columbia River study area. 35

9. Mean index of abundance (captures per 100 trap-nights) values of small mammals in segments of the Columbia River study area during 1974, 1975. 41 Appendix Tables Page

A Intensive sampling areas established in the Columbia River study area, 1974-1975. 51

B Mean index of abundance values (captures per 100 trap- nights) in small mammal intensive samplingareas inventoried. during fall 1974 and spring 19'75 in segment 1 o± the Columbia River study area. 57

C Small mammal captures per 100 trap-nights and species diversity index values by trap station type in habitats inventoried in segment I of the Columbia River study area. 58

D Mean index of abundance values (captures per 100 trap- nights) in small mammal intensive samplingareas inventoried during fall 197L1. and, spring 1975 in segment 2 of the Columbia River study area. 59

E Small mammal captures per 100 trap-nights and species diversity index values by trap station type in habitats inventoried. in segment 2 of the Columbia River study area. 61

F Mean index of abundance values (captures per 100 trap- nights) in small mammal intensive samplingareas inventoried during fall 1974 and spring 1975 in segment 3 of the Columbia River study area. 63

G Small mammal captures per 100 trap-nights and species diversity index values by trap station type in habitats inventoried in segment 3 of the Columbia River study area. 65

H Mean index of abundance values (captures per 100 trap- nights) in small mammal intensive samplingareas inven- toned d.uning fall 1974 and spring 1975 in segment 4 of the Columbia River study area. 67

I Small mammal captures per 100 trap-nights and species diversity index values by trap station type in habitats inventoried in segment 4 of the Columbia River study area. 69

J Mean index of abundance values (captures per 100 trap- nights) in small mammal intensive samplingareas inventoried during fall 1974 and spring 1975 in segment 5 of the Columbia River study area. 71

K Small mammal captures per 100 trap-nights and. species diversity index values by trap station type in habitats inventoried in segment 5 of the Columbia River study area. 72 Appendix Table Page

L Mean index of abundance values (captures per 100 trap- nights) in small mammal intensive sampling areas inventoried during fall 197/+ and spring 1975 in segment 6 of the Columbia River study area. 7/4

M Small mammal captures per 100 trap-nights and. species diversity index values by trap station type in habitats inventoried in segment 6 of the Columbia River study area. 76 LIST OF FIGUR

Figure Page

1. Segments of the Columbia River study area, 1974-1975. 4

2. Small mammal trap placement at trap stations 1-16 located at 33-rn intervals along a 500-rn transect in intensive sampling areas of the Columbia River study area, 1974-1975. 15 OCCURRTCE AND RTIVE ABUNDANCE OF SMALL MA?ALS ASSOCIAT WITH RARIAN AND UPLAND HABITATS ALONG THE COLLTh2IA RIVER

1TRODUCTION

Flooding of riparian habitat to create the existing hydroelectric generating plants on the Columbia and. Snake Rivers drastically reduced riparian wildlife habitat (Eicher 1968, Gibson and. Buss 1972, Lewke and

Buss 1.977). Currently the principalower supply system of the Pacific

Northwest is hydroelectric.Plans for the future power supply incorpo- rate a thermal system for base power needs and. employ existing hydroelectric plants for peak power demands. Use of hydroelectric plants for power peaking demands will increase the frequency and severity of water fluctuations. This modification further threatens wildlife resources associated with the remaining r±parlan habitat of the Columbia and Snake

Rivers (Johnsgard. 195, Stanford. Research Institute 1971, Clarie et al.

1971).

The. Wildlife Work Group, established by the U.S. Army Corns of

Engineers to coordinate wildlife research as it relates to water regula- tion of the Columbia and. Snake Rivers, determined that an inventory of riparian hab1.tats and associated wildlife populations was the first research priority. The area of interest was the Columbia River from its mouth to the Canadian border and. the Snake River unstream to and, includ- ing Brownlee Reservoir.

The portion of the study on the Columbia River from its niouth to

McNaxy Dam was conducted by the Cooperative Wildlife Research Unit at

Oregon State University (Tabor 1976).ALthough the base study involved 2

all wild. vertebrates excluding fish, only Information on small mammals

is presented in this paper.

Numerous sources of information on ma.mmalian occurrence and. distri-

bution in Oregon and WashIngton axe available (Bailey 1936, DaJ4uist

19L.8, Hall and Kelson 1959, Burt and. Grossenheider 1964.,Ingles 1965,

Gordon 1966, Lauckhart 1970, Larrison 1970, Maser and Storm 1970, 1lerts

1971, Olterman and. 1lerts 1972). Field. collections by the Bureau of Biol-

ogical Survey (Bailey 1936) supplied most of the intial informationon

occurrence and distribution of niaminals in Oregon and, along the Columbia

River. Current information that is available concerning mammalian fauna

along the Columbia River, however, is limited and general, and restricted

primarily to economically important game species and furbearers (Ives

and Saltzman 1970, Stanford. Research Institute 1971, Suring 1975).Small

mammals and other non-game species have received little attention (Gordon

1966, Stanford Research nstitute 1971, Battelle, Pacific Northwest

Laboratories 197k', Hedluzid. and. Rickard. 1976).

The present study was initiated with the following objectives:

(1) to examine small mammaloccurrence and. distribution in riparian and

upland habitats of the lower Columbia River; (2) to determine whether the abundance of certain species and oups of species varied among habitats within a senent of the study aa; and (3) to determine whether the abundance of certain species and. oups of species varied among segiients of the study area. 3

STTJDY AREA

Climate

The study area extended from. the seaward end of the Columbia River

jetties to McNary Dam, a distance of approximately292river miles.

Climate of the study area, discussed by Franklin and Dness(1973),

Lynott(1966),and Rudd(1962),changes from maritime in western Oregon

and. Washington (characterized, by heavy precIpitation and. mild tempera-

tures) to a continental climate east of the Cascade Mountain Range

(characterized by low precipitation and more extreme temperatures).

Annual precipitation in the study area ranges from 180 to 250 cm at

Astoria, Oregon (RN givermil7'13)to 10 to20cm at Umatila, Oregon

(RI 289). January mean minimum and. July mean maximum temperatures range from 0.0°C and20.0°C, respectively, at Astoria to -5.0°C and

0 33.5C, respectively, at Ijmatilla (Franklin and Dyrness1973).The

Columbia Gorge is- the area of transition from marine to continental climate. Weather disturbances there occur frequently, particularly during the winter when marine low-pressure systems moving westerly collide with cold. continental air.

Description of Seients

Thestudyarea was divided into the following six seients (Fig. 1);

(t) RN 0 to RN 12 (mouth of Youngs River); (2) RN 12 to RN79;

(3)RN79 to BonnevilleDam (RN tL.5); (L.)Bonneville Pool (RN 1LI.5_192); (5)The Da1J.es Pool (RN192-215.6); and(6)John Day Pool (RN215.6- 292). (J Figure 1. Segments of the Columbia River study area, 1974-1975. Plantromenclature follows that of Hitchcock and. Cronquist (197). Segment 1--Wet beach and stabilized foredunes characterized the mouth of the Columbia River.Vegetated foredunes were dominated by beachgmass (Ammophila arenaria).Tidal marshes and mudflats occurred on the immediate river shoreline near the mouth and were submerged daily by incoming ocean tides.Sitka spruce (Picea sitchensis) was common in the intertidal zone and near the river mouth, but red aider (Alnus rubra) dominated most recently disturbed and poorlydrained bog sites in intertidal areas. Segment 2--Riparian vegetative communities of Sitka spruce, black cottonwood (Populus trichocarpa), and dense, tail shrubs suchas creek dogwood (Cornus stolonifera) and several willow species(Salixspp.) were characteristic of shorelines and borders of tidal flats and channels in the western portion of segment 2.Islands in segment 2 closer to the mouth of the Columbia River were subject to major tidal influencesand were mainly marshy tidelands.Islar4s farther rpriver were characterized. by tall, dense shrub communities with scattered. Sitkaspruce, red aider, and black cottonwood.The coastal climatic influence, appar- ent in segment 1 and. indicated by the presence of Sitkaspruce, emctended eastward, in segment 2 to CathlanietWashington (pL.O41).Above that point in this segment, river island and shoreline coinn'iunitieswere more tyDically riparian forests of black cottonwood and willow species (Franklin and, Dyrness 197j). Segment 3--In this segment most of the river shoreline and islands were characterized by sandy beaches bordered by long, narrow stands of black cottonwood/Pacific willow (Salix lasiandza). Black cottonwood was the dominant tree species, although Pacific willow often dominated lower areas exposed to high water. Oregon ash (Fraxinus lati±'olia) had a scattered distribution arid usually remained under the main forest canopy.

Near Sauvies Island (RM 87-101) Oregon ash increased, in density, d.cini- rating scattered sites. Typically, creek dogwood, Pacific blackberry

(Rubuursinus), Himalayan blackberry (R. discolor), and. snowberry

(Symphoricarpos albus) were understory shrubs, but yielded to extremely dense stinging nettle (Urtica dioica) and reed canary'ass (Phalaris arundinacea) stands. Stinging nettle was the dominant f orb under a black cottonwood canopy. Reed canary'ass dominated open areas and was a codominant species in bl.ck cottonwood/Pacific willow ecotones.

Columbia River willow (Salix fluviatilas) and. Pacific willow formed dense star4s on sites subject to frequent flooding.

Senent L_A niesic to xeric vegetation adient occurred from west to east in seaent 14. The valley floor and lower slopes of the steep gorge in the west end of this seent were occupied by mesic coniferous forests, largely Douglas fir (Pseudotsuga menziesii) and western hemlock

(Tsuga heterohylla) with scattered bigleai maple (Acer macroohyllum).

Snowberry, vine maple (A. circinatum), poison oak (Rhus dversioba), salal (Oaultheria shallo n), and Orego n'ape (B er'oeris spp.) were dominant understory shrubs. Eastward, onderosa pine (Pinus onderosa)

ad.ua1ly replaced Douglas fir/western hemlock communities. Oregon white oak (Q.uercus garryana) was dominant on xeric sites and, formedan association with pondarosa pine on slopes near the river.Snowberry, vine maple, poison oak, bitter1rush (P'sia triden±ata), and. tall 7 Oregonape (Berberis aquilfoliuni) were major shrub species in ponderosa pine/oregon white oak communities.Idaho fescue (Festuca id.ahoensis), bluebunch wheat'ass (Aopyron spicatuin), and, cheatass (Bromus tectoruin). were dominant ass species. Poison oak formed extremely dense stands ur4er Oregon white oak canopies.Snowberry, creambush ocean-spray (Holodiscus discolor), and dull Oregonape (Berberis nervosa) added to the shrub diversity.

In the eastern end of senent L.forest vegetation was replaced by semi-arid, steppe vegetation.Cliffs with steep talus slopes formed the gorge walls in much of this area.Grasses, predominantly cheatass and.Sandberg's blueass (Poa sandbergii), covered slopes having a soil layer.Shrubs were found on slopes below cliff faces, talus, and narrow, steep-walled creek bottoms.Maples (Acer spp.) dominated the creek bottoms;ceanothus (Ceanothus spp.) and bitter cherry (Prunus emargi- na-ta), the talus;and. bitterbrush arid rabbitbrush (Chrysothamnus spp.), the slopes. Pacific willow, Columbia River willow, and. peach-leaf willow (Salix amygdaloides) formed dense stands on low, moist sitesnear the river. Reed canaryass dominated the ur4erstory.Subject to frequent flooding, some sites accumulated large amounts of driftwood and. had sparse herbaceous understories consisting primarily of sedges (CarexsDp.). In addition to riparian vegetation, rock rip-raD, a land form class, bordered. 3L. percent of the total miles of shoreline in segment Lk. Rock rip-rap, used, as foundation for railroad gmades and, highways and to ore- vent shoreline erosion, was nearly void of vegetation. Segment 5--Vertical rock cliffs with narrow plateaus above and, a

steep talus slopes and. gentle or steep sloping asslands below foned

much of the gorge walls in. segment 5. Gray rabbitbrush (Chrsothaus

nauseosus) was the dominant overstory specieson the plateaus, but bitterbrush, big sagebrush (Artemisia trid.entata), and. ceanothus occurred, sparingly. Dominant gasses covering the steep slopes beneath the cliffs and occurring as an understory to the shrubs on the plateaus were

cheatass and. Sand.'ce.rg' s blueass. Other asses present were Idaho fescue, bluebunch wheatass, bulbous blue'ass (Poa bulbosa), and. six- week fescue (Festuca bromoides). Gray rabbitbrush with a cheatgmass

understory covered most of the gentle slopes beneath the rock cliffs.

Some portions of this segment on the Washington shore were gentle

sloping asslands with few cliffs and talus slopes. Shrubs were not common in these areas. Gray rabbitbrush, bitterbrush, and buckwheat

(&'iogonuxn spp.) occurred, on a few locations around talus. Balsamroot

(Balsainorhiza sp.) and lupines (Luinus spp.) werecommon on the 'assy slopes dominated by cheatgmass, Sandberg' s bluegmass, and bluebunch wheatass.

Peach-leaf willow, slender willow (Salix exigua), ar4 Columbia

River willow were the primary overstory species occurring in small patches along the river shore and eiubayments of this segment. Pacific willow, black cottonwood, and. Great Plains cottonwocd (Populus deltoides) occurred less frequently. Herbeceous vegetation was "patchy" with reed canaryass, licorice-root (O-lychiza leoidota), horseweed (Conyza cans1ensis), western valerian (Valeriana occidentalis), and narrow-leaved milkweed (Asciepias fascicularis) occurring in. the understories.

As in. segment Li., much o± the river (L.o percent of the total miles of shoreline) was bordered. by rock rip-rap. Vegetative cover is very sparse to non-existent in this habitat.

Seient 6--Steep talus slopes below vertical cliff faces formed most of the gorge walls in the western part of segment 6. Hackberry

(Celtis reticulata), ceanothus, common chokecherry (Prunus virginiana), and juniper (Juniperus sp.) occurred sparingly in the talus. Portions of the steep slopes not covered with talus were gm'asslar4. The most common 'assez were Sand,berg' s bluegrass, cheat grass, arid bluebunch wheat grass . Gray and green rabbitbrush (Chrysothaninus viscidiflorus), buckwheat, and. a small amount of big sagebrush occurred, on the lower portions of these slopes. Big sagebrush occurred in the bottoms of moist side canyons and draws. Most of the immediate shoreline in this area was vertical rock cliffs or rock rip-rap.

Eastward, the topography changed from river gorge to gently rising slopes. Green rabbitbrush dominated the shrub layer of vegetation on slopes well above the river level. Gray rabbitbrush with a cheatgrass understory covered the lower slopes of most of the area. In scattered locations bitterbrush, big sagebrush, and. green. rabbitbrush were codomi- nants with gray rabbitbrush. Other grasses in the area were Sandberg' s bluegrass, western need.legrass (pa occidentalis), and bluebunch wheatgrass. The immediate shoreline of the riverinmuch of this area was vertical rock cliffs.

TopograDhy in. the eastern portion of segment 6 beyond the rivers edge varied from gently rising slopes to aliost flat.The area was mostly grass and shrublarid with irrigated farmland, ponds, and. ina.rshes interspersed, from approximately iM 270 eastward. Gray and, green rabbit- 10 brush were the major shrub species, and big sagebrush and bitterbrush dominated the sandy areas. Cheatgrass and Sandberg s bluegrass were the major grasses.

Much of the river shoreline was sand and rock rip-rap in this east- emportion of seaent 6. Great Plains cottonwood, peach-leaf willow,

Russian olive (Elaeagnus anustifolia),. and. locust (Robinia sp.), however, occuied in patches along the river shore and many of the ponds, marshes, and. sJ.oughs. Most por4s and, marshes in ths area supported lush growths of marsh vegetation dominated by common cat-tail (Typha latifolia), bulrushes (Scirpus spp.), rushes (Juncus spp.), sed.ges, sweet-clovers (Nelilotüs spp.), and. water smar-tweed (Polygonum coccineun).

Intensive Sampling Areas

cisting broad. vegetative types (based on vegetative overstory) and land form classes (those areas without vegetation) within the study area bound.aries were identified and delineated from aerial photographs.

Identification and delineation on. photographs were verified by field observations made from air and ground checks. Acreage estimates made from the photographs with a dot grid were used to determine the major vegetative types and. land. form classes (habitats) within each seaent

(Tabor 1976:2+1-5).

habitats located near the river shoreline (ripaxiazi habitats) were considered to be of greater importance in this study than habitats at higher elevation within the study area. Intensive sampling areas were established. in ripaxian habitats and in each major vegetative type and land form class identified in each senent of the study area. Intensive 11

sampling areas were not established, on ir4ustrial, residential, or cu.l-

tivated lands.

An intensive sampling area was established on both the Oregon and

Washinon shores in each of the major types of habitat that occed

in each seiient. In senents 2 and 3 an intensive sampling area was

established in each major habitat on an island. Intensive sampling areas were located in "homogeneous" stands of the habitat and,, where feasible, wefl inside the boundaries of the habitat to avoid "edge effect."

Tabor (197684-268) presented the exact location, physical characteris-

tics, and, vegetative community of each of these intensive sampling areas. 12

.THODS

Sampling

In small mammal studies two fundamentally different types of trap-

ping have been used to estimate population densities. In one, animals

are marked and. released into the population from which they were cap-

tured. In the other, animals are removed as captured.

Mark-ar4-release trapping makes possible the study of many phases

of life history (Hayne 1949, Blair 1940a-c) and leaves fauna in nearly

the same conditions for further studies (Dice 1931,1941). For exten-

sive studies, however, this method is too laborious and, time consuming

and is not practical for sampling a large number of habitats in a short

period of time (Stickel 1948).

The primary objectives of this study were to determine occurrence

and relative abundance (not population densities) of small mammals in

numerous habitats. A simple field method, with equalized intensity in

all sampling areas, was needed, therefore, to inventory a variety of

small mammals in a short -time.Mark-and-release trapping with a single

trap type and removal trapping with a id or quadrat arrangement to

estimate population densities (Stickej. 1946, Hayne 1949, Zippin 1956,

1953) were impractical.

Relative, index figures for a species (rather than density estimates),

calculated from captures along trap lines of measured lengths and. main-

tained for a standard number of days, are comparable for different habitats, seasons, or areas (Dice 1931, 1938,1941, Southern 1965,

Hansson 1967). The assumption that alJ. individuals of a species or 13 species oup have the same probability of capture in all habitats and areas (segments) during all sampling periods is inherent in comparing the relative abundance of a species or species ou among habitats and segments.

Removal trapping with a variety of traps in a standardized sequence along a line transect was used to inventory small mammal populations in intensive sampling areas during two sampling periods. The fail 197L sampling period began 17 August in segment 1 and was completed 30 overn- ber in segment 6. All 82 intensive samling areas were inventoried with at least two consecutive trap-nights during the fall inventory. The spring period was 3 May-15 July 1975. Order of sampling was segment 3

(some sampling areas),L. (some sampling areas), 5, 6,1, 2, 3, (some sampling areas), and Li. (some sampling areas). An attempt was made to inventory areas of low elevation before spring high water flooded them; those areas sampled first in segments 3 and. Li. were such areas. Fifty- four sampling areas were inventoried during the spring sampling period with at least three consecutive trap-nights. Only capture data gathered during the first two consecutive trap-nights were used for relative abundance comparisons among habitats within a segment.This protocol was a4opted because data collected during both sampling periods in intensive sampling areas of similar habitat within a segmentwere combined.

Trap stations were established at 33-m intervals along a linear transect within each intensive samltng area.The length of a transect varied according to the size of the intensive sampling area; but a 13 station, 500-m transect was the maximum length. One baited and one unbaited Museum Special snap trap were set at each trap station. In 1L addition, baited Victor rat traps, baited Sherman live traps, andUn- baited pitfall traps on the ound and baited Museum Special snap traps and baited Sherman live traps in trees were used in a standaxdized sequence as shown in Figure 2.These standardized traps were located within a 5rn. radius of each station.Additional traps such as No. 110 and 220 Conibear traps, Cinch and Victor gopher traps, and. 0u-O'Sight mole traps were used where sign and. appropriate conditions occurred; thus these traps were not included in the standardized sequence. To attract a gneater diversity of mammals and still simplify the procedure for baiting traps, a bait mixture consisting of beef suet, peanut butter,gmcund raisins, oatmeal, and. parafn wax was used (Tab er and Cowan 1971). Captures in all trap types during all trap-nights, visual sightings, tracks, scat, and. other sign recorded in each habitat were used to docu- ment the occurrence of species.Small mammal species identified in this study are referred to primarily by common name throughout this paper.Scientific and common names presented in Table 1 follow Jones et aJ.. (1975).

Index of Abundance

An index of abundance (bA) value for each capturedspecies and oup of species (e.g., voles, mice, insectivores, total mammals) by trap station type, intensive sampling area, habitat, andsegment of the study area was expressed as captures per 100 tra-nights.Only captures in standardized gnound traps were used in calculatingthese bA values. Capture data from intensive samplingareas of similar habitat and both sampling periods were combined to determine bOA valuesby habitat and. 2 3 5 'I, 16 1° .. 0. VI. 1 o V MuseumVictorMuseum Special,Special unbalted baited ®Li4' BalledPitfall,Sherman, MuseumRat, balled Special,unbolted tree bailed Figure 2. Small mammal trap placement at trap stations 1-16 located at 33-rn intervals Baited Sherman, tree stulyalong area, a 500-rn 197't-1975. transect in intensive sampling areas of the Columbia River I- 16 seient. An IOA value for each captured species and oup of species was determined, for each o± the three traD station types (Fig. 2).The

IOA value was calculated in the following manner: the number of individuals of a species or species oup caught in ound traps of a particular trap station type during the first two sanpling nights was divided by the number of star4axdized ound traps of that trap station type used during the first two nights.This quotient was then multiplied by a factor of 100 to obtain the IOA value for a species or species

'oup by a particular trap station type. This calculation was made for each of the three trap station types for all species and oups of species caught in each habitat within a senent.

A mean bA value for each species and species oup in a habitat was calculated from the IOA values for the three trap station types in that habitat. These calculated IOA values were used to compare the relative abundance of the following species and. oup of species among habitats within each senent:

Deer mouse Vaaz± shrew Total mammals Total mammals excluding deer mouse and vaant shrew Insectivores (shrews and moles)

Insectivores- excluding vaant shrew Mice Deer mouse Pacific jumping raouse Great Basin pocket mouse Ord' s kangaroo rat Western harvest mouse Northern asshopper mouse House mouse M1.ce excluding deer mouse Voles (Nicrotus spp.) 17

A mean bA value for these species and oups of species for each segme of the study area was calcu.ated from the mean bOA values for each habitat within a segment. These IDA values were used to compare the relative abundance of these species and. species oups among segments

0± the study area.

Analysis

The three IOA values of a species or species gmoup for each habitat within a segment were arranged in a randomized complete-blocI design and tested with analysis of variance (Steel and Torrie 1960). The data were transformed with the '\JX + 0.5 transformation (Steel and Torrie 1960) when 25 percent or more of these IOA values in each analysis of variance test were zeros. Differences in relative abundance of a species or species gnoup among habitats were considered statistically significant if P<0.05. Tukey's w-procedure (Steel and Torrie 1960) was then used. to test differences among habitat means.

These habitat means were arranged in a completely randomized design.

Thesedata alsowere transformed when 25 percent or more of thehabitat means were zeros. Analysis of variance for six treatments (segments) with unequal replications (habitats) (Steel and Torrie 1960) was used to test for differences in relative abidance of the deer mouse and vagmant shrew and the seven species ous among segments of the study area. Differences were considered statistically significant if P <0.05.

Tukey's w-proced.ure was used to test differences among segment means when the F-value was significant. 18

RULTS AND DISCtSSI0N

Thirty-nine species o± small niaanials were recorded in the study

area (Table 1). All species were associated with intensive sampling areas except the white-tailed jack rabbit, mountain beaver, ay

sq.uirrel, and. gay-tailed vole which were identified in areas other

than those chosen for intensive sampling.Twenty additIonal species

(Table 1) were not identified. during the study butmay possibly occur

in or near the study area. Many of these species, however, do not

occur at low elevations or are rare.

During the field. work, 11,019 trap-nights in intensive sampling areas produced 1,982 small mammal captures. Although 23 specis were captured (Table 2), deer mice and. vaant shrews collectively comprised

81+.9 percent of the small mnairurials captured.

Seient1.

0ccirence--Moist climatic condItions and. the resulting lush veg-

etation appear to be ideal for insectIvores which made zp one-third. of

the 18 small mammal species identified in seient 1 (Table 3). Insec-

tivore species captured by Tabor (1977) occed mainly in damp habitats.

Ingles (1965:81) states that InsectIvores "on the Pacific Coast are

nearly all inhabitants ol' damp, moist' places."

Ten species of small mammals, whose ranges according to B'b and

Grossenheider (t96L.), Ingies (1965), Maser and. Storm (1.970), and. Verbs

(1971) include all or part of seaent 1,were not identified in this senent (Table i). These species, many inhabitants of coniferous 19 TABLZ 1.Snail naaina.Ls ocrir1 along the Colth1a1ver.Sti.:r area aeçients listed, after species represent :ane accordingto various authors. '4erscoring.enotes QCO'.1CC iX1 this st'y. SpecIes b ange acd. SpecIes ?.ange az. (Scientific Name) Occin'rence (Scetific Nace) Occence

Iagra.nt - 21 Western rocket gopher (Sorex van) I çThocnys ta) 9 3 USk73br9W Caa ocket gopher (S. obsc'.$) 1 1 (T. buIbivors) 2 Water skew Great 3asin ocket nouse 6 (s )° (Pereathusar'rjs) Pacific water s'ew 1 Ord s kacgaroo rat (. beed.irii) 2 - (Dtd.c'rs jj) - Trowbride's 3bZ9 1 Western harvest jtouse (3. troubrid.g.t) 2 - (Rettcd.ontotiris nea1otis) 4 Merrian's snrew Deer nouse (s.taerrtani) (?eroinyscus nanlouJ.atus Shrew.-fnole CanyOa nouse (Neotrichus sii) -. 2 (. crnitus)° Towtseri' s nole 1 Northern grasshopper rtouze (Scaranustownser4lt)5 (Onychomys leucoaster) )2 Coast tale 1 21 , : Dusky-footed woodrat (3. crarius) - (Neotoma. fuscises) Pika, Bushy-tailed wocd.rat (Ochotona orinces)C 1 (i. cinerea) 1' . 6 3r'ish rabbit Southern red-backed vole 21 (Cletonomys aver) astern cottontail Western red-backed vole (S. fiortdanus) (C. occtdento,lIs) - Ni.ttail's ccttontaU. L. Heather vole (s.nuttaflii) 6 (Phenacouysintarnedius)C - Snowshoe hare , / ihite.zooted vol .. . (Laus emericaiuz) - (P. a.lbises) White-tailed, jack rabbit Red tree vole (L. towrjer,d,ii) 2 (. longca14us) 4 h Black-tailed. jack rabbit MOrIt3. vole - (L. coraicus)1' (?icrotus nontarnis) 2 Mountain beaver Gray-tailed. vole (Alcdontta r1,'a,) (M. ajcaua) 2 Lea.st cbipntunk. - - Townser.'s vole (utania.s nininwa) (. torserii) 1 , eUow-oine chjomuk Long-tailed vole - (I. amoenus) (T. lorgicaus) . 2 2 Townse's 2 3 Creeping vole (L townsendii) (c.oreor.i) 1 ellow-beUied. narnot. Water vole (Marnota fiav-tventrjs) (Ar'ricola r±charIsorI)° Townser' s ground sq,uirrel Sagebrl2szl vole 6 6 (SoerrnohiJ,uz townser4ll) (Lagz'us c'atus) iashingtor. grourd so uiel 3lack rat (s. vashiorij ) ' (Rattus rattuz) Ca.li±'orhia Torvay rat 7 (, beechevt) (3. norve.ous) -6 Gcld.en-fnaatled. grouz. squirrel - House mouse (S. latera.ijs)° ( nusculu.$) 2

Dray squirrel Western j.opingnouse - (ScI'.s caro1ner.ss) (Zaous orizinecs) Western gray scuirrel Pacific j'nming mouse , - (s.zriseus)r 1 - Dougl' sq.uirrel (. trtotatus) .. - - ine(short-tailed wea.sel) - (Taat.iaaci'z d.ou1asII) (Mu.stela ermina) ' 2 Northern flying squirrel , , Long-tailed weasel Glaucontys sabrinus) (. frenata) 9 4 Northern pocket goner (Thomomysalooides) a(.Terts 1971, Maaer and. Storn1970, LngJ.es1965, Cart.redInnon-staardized.raos only. nod.Grossethelder1561.1.). Gbserved or Identifiedby sign. (Jones etaL. 1975). Totrecorded.IAintensIve sanpllngarena. igh elevations. hStatus urdeternined.(Olternanand. Ter-n Rare (Olterman and. Terts1972). 1972). 20

TABLE 2. Total number of individuals of each mammalian species captied. in stand.ardized ground. traps in intensivesampling areas of the Columbia River study area in fall 1974and sDring 1975.

Segment

Species 1 2 3 4 5 6 Total

Insectivora

Vagrant shrew 110 77 111 4 302

Dusky shrew 9 3 1 13 Pacific water shrew 2 2 4

Trowbridge's shrew 11 7 18

Shrew-mole 6 1 3 10

Coast mole 1 1 Rodent ia

Townsend's chipmunk 1 5 6

Northern pocket gopher 1 1

Ord's kangaroo rat 9 9

Great Basin pocket mouse 2 32+ 36

Western hsvest mouser 1 1 33 35 Deer mouse 48 133 352 247 263 338 1,381

Northern grasshopper mouse 1 1

Bushy-tailed woodrat 5 4 5 14

Montane vole 7 3 10 Townsend's vole 5 8 41 6 60

Zng-tailed vole 2 3 13 18

Creeping vole 33 1 34 House mouse 14 14

Norway rat 1 7 8

Pacific jumping mouse 3 1 Carnivora

iine (short-tailed weasel) 1 1

Long-tailed weasel 2 2

Total 232 228 509 299 270 L1 1,982 Trap-nights 11461,8632,4361,746 1,0142,814 11,019 21

TJ3LE 3. ean index of abur4ance (caDtss oer tOOa?-rd..hts) values o sma.11 sa.wsals in ha'oinats inventoried. in saiest I of the OcJ.usbia iver study wea. Habitat 3eachass ialarsh Ald.er (2Y (3) (2) Species orroixo (38L)° (396) (366)

Vaast snrew 9.5 jj.Q 5.2 Duskyshrew 0.3 0.3 2.0 Pacifto water shrew 0.6 i'rowbri4e' s shrew 3 .0 S1ew-mole 0.3 0.3 1.2 Coast sole 0.2 3rush rabbit C Snowshoe hare

Towr,sez.' a chipmunk . 0.2 Califori.a rcusd. squ±rsel Doula.s' sq.uirrel Deer souse 3.7 2.9 6.3 Townsend.s vole 0.3 3.5 Long-tailed. vole d Creeping vole 2.5 6.3 Pacific ji.sroisg souse 0.5 0.3 Short-tailed 0.6 g Long-tailed. weasel 0.3 Thta.1. samma.ls(TCA) i6. 26.0 19. TCMA-d.eer souse'ivaast shrew 3.3 9.1. 7.3 Insectivores 10.3 LLI..6 11.9 Iosectivores- vaastshrew 3.3 0.6 6.3 ?fice 3.7 3.i. 6.6 ce-d.eer souse 0.5 0.3 7olaa 2.5 7.2 0.5 aThtensj.ve sarolingareas were sanrled 2,3or L.ccnsecut1.veizhts in fall 197L and. 3 or Li.consecutive nights is soring1975,however, only the capte data. ±''om the first 2 ni..ghts were used to ca.lculate captes per 100 trap- nights because data from both seasonsa.ed.intensive saroUng areas of sizsilar were comb med.. DTh.nnbers isarentheses eciia.l thtanstve samoling areas of sisilar habitat. isarerxtheses equal rar-nig±rts d'str.g first 2 nights. dCaotl.dafter aecor4 night. CNctcartred., out was observed. and/oridentifiedby sign in thts habitat. Capttred. in non-staardized traps only. rot recorded. in thtansve saring areas, but was observed Is this habitat. character sueracrjota denote significant d.ifferer.ces among habitat scans at the5 ercent level or less (a.naiysis of variance).The results of the sean separation tests (Tukey s-prncethre) are d1.aamed.eanz u.erscored, by the same Lifle are not signifIcantly different. Ald.er 3eachassTIdaJ.ersh 6.8 0.3 0.6 22 forests, may occur in habitats other than those sampled in segment 1.

elative abundance--The vaant shrew, deer mouse, dusky shrew, and shrew-mole were captured in alJ. habitats sampled (Table 3). 1ean

IOA value for the vaant shrew was higher in tidal marsh habitat, whereas mean 1OA values for the dusky shrew, shrew-mole, and deer mouse were eater in Alder.No species abundance, however, differed statistically among habitats.

The gmoup insectivores excluding vagmant shrew was the only species gmoup differing significantly in abundance among habitats. This species gmoup was significantly more abundant in alder habitat the' beachgmass and tidal marsh (Table 3). Alder is probably better habitat for these insectivores due to the presence of many insects and other invertebrates associated with a gmound cover of deep, moist litter.

Insectivores were predominant in all habitats sampled in this segment. They made up 63 percent of the total mammals captured in beachgmass habitat, 56 percent in tidal marsh, and 61 percent in alder.

Senent 2

ccirence--Seventeen species of small mammals were id,entified in habitats sampled intensively in segment 2 (Table 4). Three additional species were identified in tes of habitat other than those sampled intensively: the snowshoe hare and mountain beaver were found in maple/'Douglas fir, and Douglas squirrel was observed in alder.

Aarently environmental conditions are almost as advantageous for insectivores in segment 2 as in segment 1; one-fourth of the 20 small mammal species found, in segment 2 were insectivores. 23

TABLE Li.. Mean ind.ex of abt (caotures cer 1.00 trap-rihts) values of amail sammala in habitats inventoried in aeaent 2 of the Colunbia. River stu±f wea. abitat

Tid.al Tid.aJ. Cotton- Reed Tidal Sth Sieka Cotton- wood/ Can- Mah willow Spruce WOOd iC.low itllow paSs (4)b (2) (3) (2) (t) (2) (2) Species or roup (Li.02)° (174) (249) (288) (192) (298) (270)

1Taaat sbrei 4.3 1.7 3.0 3.8 3.1 2.7 9.0 Dusky strew 1. .2 Pacificwater sgw 0.5 Trowridga'skxev e Tow zezs o1e a a a Brush rabbit a a st cottona..3. a a TownseOd' a chipmunk California squirrel a g 1orthern flying squirrel Deer nouseb 5.4 0.6 17,0 1.0 1.1.8 1.4.3 0.3 TownseOd's vole 0.4 0.5 1.5 0.3 Long-tailed. vole 0.6 Creeping vole 0.4 tarway rat 0.2 a Pacific ji.mrping noune 0.3 Long-tailed weasel Total ma1 (TMA) 1.0.7 2.4 21.Z 6.2 15.3 18.5 10.1 TOMA-dear mouse #vaan't skew 1.0 1.2 1.4 0.5 1.5 0.8 Thsectivores 4.9 1.7 4.2 3.8 3.1 2.7 9.0 tsetivoras-vaant shreW 0.5 1.2 Mice 5.6 0.6 17.0 1.0 1.1.3 14.3 0.3 Mica-deer mouse 0.3 Voles 1.4 0.5 1.5 0.3

Thtensive samolizig wea.s were sanpied 2,3or Li. consecutive nights in fall 1974 and3or consecutive nights In spring 1.975, however, only the captte data from the first 2 nights were used, to calculate ca.ottzea per 1.00 trap-nights because data from both seasonsandinten- sive sa]..thg areas of sisilar hattat Were combined. bNbersinarentheses equal intensive samp1.ng areas of sinilar habitat. inerentheses equal trap-nignts thring first 2 nights. dCated.after second. runt. Tot caot.red, but was observed. and/or td.entifieby sign in this habItat. :Cttzd. in non-standardized trans on.ly. ot recorded, in intensIve sampling areas, but was observed in this habitat.

Touble character auoeraipts denote sIgnificant differences amor.g habitat teans at the5 percent level or lass (analysis of varla.nce),The results of the team separation tst (Tukey a-proced.tre) are diaamed..Means underscored, by the sane lIne are not signifIcantly different.Means und.erscored. by the sane dotted line &iffer by exactly . Reed. Tidal Tida.]. Cot-touwood/ T1.da.i. Marsh Cottonwood. iillow Sitka. Scrca tllcw 3ub Jillow 9.0 L1..3 3.3 3.1. 3.0 2.7 1.7

bb Tidal Dottonwood/ Tidal T1.dal Reed. Sitka Spruce (W.ow iU,low Marsh Cottonwood. 3ub willow Canarya.ss 17.0 1.4.3 11.3 5,4 1.0 0.6 3.3

° TIdal Cottowod/ Tidal Reed. TIdal Sitka oruce iillow tllow Marsh Canaryasa ottonwocd Sith willow 21.2 18.5 15.3 1.3.7 10.1 6.2 2.4 2L.

T.BLE Li., oritnued

seed. T4a1. Cttotwood/ Ta1 Ca.arçzs ski Sitka SpruceCottonwood. Jillow Sb tUow 9,0 Li..9 2.7 ce Tida.L Cottwcd./ .daJ. T4a1 aeed SLtka Soruce iUiw iUow Maz'i CottonwoodShb WillowCanary.s t7.0 1L.3 5.6 1.0 0.6 0.3 Ten small mammal anecies, whose ranges totally or -artiaily include senent 2, were not found in this segaent during the study (Table 1).

Three of these species, the shrew-mole, coast mole, and short-tailed weasel, were found. to occur in this senent at the Trojan Nuclear Power

Plant site (RN 72) during a study conducted by Battelle, Pacific North- west Laboratories (197L.). The other seven species (i.e., western and.

Camas pocket gophers, bushy-tailed woodrat, southern and western red- backed voles, white-footed vole, and. red tree vole) may occur in habitats not sampled in senent 2. The voles we inhabitants of moist coniferous forests (Maser and Storn 1970). One record of the white- footed vole in this senent was reported for 7 miles southeast of Rainier,

Columbia County, Oregon (RN 7+) by Olterman and Ver-ts (1972). Maser and Storm (1970:69) state that this species is 'the rarest maicrotine rodent in North America."

Relative abundance--The vaant shrew and, deer mouse were trapped

in all habitats sampled (Table !.). Both species differed significantly

in abundance among habitats.

The va'ant shrew was significantly macre abundant in reed, canary-

ass habitat than in willow, tidal Sitka spruce, cottonwood/willow, and tidal shrub willow (see miieazl separation results, Table L). The highestOA values for the vaant shrew in seaent 2 occurred in reed. caryass and tidal marsh habitats possibly indicating a preference for non-forested habitat. It also may indicate the eater tranability of vaant shrews in habitats where deer mice were not abundant as was the case in reed canaryass and tidal marsh. Vaant shrews collected by hitaker and Maser (1976), however, were found in non-forested areas. 26

In contrast to the vaant shrew, the deer mouse had. the lowest mean bA value in reed canaryass habitat. Deer mice were most abundant in tidal Sitka spruce, cottonwood/willow, and..wilow habitats which did, not differ significantly in deer mouse abundance; deer mice were significantly less abundant in tidal marsh, cottonwood, tidal shrub willow, and reed canaryass (Table Lb).

Three oups of species (i.e., insectivores, mice, and total manm.als) differed significantly in abundance among habitats. Insect i- vores and. mice were principally represented by vaant shrews and deer mice, respectively, and. therefore abundance differences for both species gno ups were similar to differences for both species. Total ma.mxnaJ. abundance, as deer mouse abundance, was not significantly different among tidal Sitka spruce, cottonwood/willow, and, willow habitats (Table L).

Insectivores, mainly vagnant shrews, wereredominant in three habitats, whereas mice, principally deer mice, predominated in the remaining four habitats. Insectivores made up 89 percent of the total mammals captured in reed canaxygi'ass habitat, 71 percent in tidal shr'.b willow, and. 61. percent in cottonwood. Mice composed 52 percent of the total mammals captured in tidal marsh habitat, 80 ercent in tidal Sitka spruce, and. 77 ercent in both willow and cottonwood/willow.

Seçnent 3

Occurrence--In this seient 13 small manunal species were found. in nactats samledr..-tensvely (Taoje ). Iricio.ental observations of three additional species were made in types of habitat other than those sampled intensively. Townsend' s chipmunk and. Douglas' squirrel were 27

TABLZ5. !eaisdex of abuance (captures per 100 trap_.r1ita) values of 5911 oasjnals is habitatsventor1ed is seert3of the Coluba 3iver studyarea. :abitat Ash/ Cotton-Cottonwood./ iUow/ Canary- Shrub wood..(3)0 Willow Cottonwood sss Willow Willow (j) (3) () (j) () SpecIes or Grou (L4.32)' (L1.62) (3814.) (3614.) (3611.) (390)

7aat shrew 6.2 11..3 5.3 3.7 2.3 1.11. Ousky shrew 0.3 Shrew-mole 0.3 'owr.zend,'s sole Srush rabbit Sastern cotthtail C C C C C Californi_.a OUnd squirrel £ Graysquirre]. Northern flytnsquirrel Ceer souse 16.3 22.0 1.5.2 5.8 1.8.0 .2 Townsend's vole 0.9 2.2 0.5 2.14. 2.14. 1.9 Long-tailed, vole 0.6 tong-tailed. wesal Total saawiai.s°° (TOMA) 23.5 29.0 21.2 1.6.8 23.0 1.0.14. TOMA-deer souse +vaant strew 0.9 2.8 0.3 2.14. 2.7 1.9 Zosectivores 6.2 11..3 5.6 8.7 2.6 1.11. Ensectivores-vWant shrew 0.3 16.3 22.0 15.2 5.8 13.0 .2 Mice-deer tou.se Ioles 0.9 2.3 0.5 2.14. 2.14. 1.9

aThtensive samnlisgareas were saspled 2, 3 or L consecutive nights is fall 19714. arid3or consecutive nights is anring1.975,however, only the caoture data from the first 2 nights were used, to calculate ca;teser 100 trao-n.t.ghts because data front both seasons and Intan- sive sanmling areas of sLsilar habitat were combined. in oarertheses equal intensive samplIng area.s of aislar habitat. :rbers is parentheses equal trap-nights ding first 2 nights. dCaDtedin ion-standardized traps on.ly. Tot caotured, but was observed and/cr i4ent.ed. by sign is this habitat. Tot recorded is 1rten.sive sampling areas, but was observed is this habItat. Touble character supersortpts denote signifIcant differences anorig habitat aea.ns at the 5 percent level or less (analysts of vartance). e results of the teas searatton tests (Tukey' a w-procedure) are itaaned. Means underscored, by the same line are riot signifIcantly dferezrt. Cottonwood/ l.sh/WUlow/ Reed Willow Willow Cottonwood,Cottonwood Shrub WillowCa.nsryra.ss 22.0 18.0 1.6.3 15.2 7.2 5.3

Ash/Wiilcw/ Reed Willow Cottonwood Willow Cottonwood Casaryass Shrub Willow 29.0 23.5 23.0 21.2 1.6.8 28 observed in maple/Douglas fir, and theay-tailed vole was found in aicultural lands. Sampling methods, limiting the inventory to riparian habitats, and. the low vegetative diversity among these habitats may explain why jLf the 30 small mammal species whose ranges include at least part of senent 3 were not encountered (Table 1). Relative abundance--The vaant shrew, deer mouse, arid Townsend' s vole were trapped in all habitats sampled (Table.5). The mean 1OA value for the vaant shrew was highest in reed canarygtass habitat as in senent 2.Mean bA values for Townsend.' s vole were highest in reed canaryass and. willow, whereas the mean deer mouse bA value was highest in cottonwood/willow.Only the deer mouse, however, differed significantly in abundance among habitats. The lowest deer mouse bOA values, as in segnient 2, were recorded in shrub willow and reed canaryass habitats.In senerit3these bA values were significantly less than deer mouse IOA values in cottonwood

/willow and willow habitats (see mean separation results, Table5). The structural dissimilarity of the twooups of habitats, forest and. non-forest, may account for this difference.:iedlund and. Rickard. (1976), studying small mammal poulations near the Trojan Nuclear Power Plant

(R'i 72) in senent 2, captured fewer deer miceiflmeadow than in forest habitat. Two species oups, mice and total mammals, were significantly different in abundance among habitats.Because deer mice were theonly mice in that species oup, abundance differences among habitats were the same as for deer mice.Total mamzaal abundance in cottonwood/willow 29 habitat was significantly eater than shrub willow (Table 5). The

amount of sinai.]. nianunal microhabitat (e.g., ound cover, runways, holes) was less and frequency of inundation from water fluctuation was eater

in shrub willow than the other habitats. These two factors may account for the lower total mammal abundance in shrub willow habitat.

Deer mice made up a substantial amount (66-78 percent) of the total mammals captured in all habitats except reed canaxyass. Vaant

shrews composed 52 percent of the total mammals captured in reed canary-

ass habitat.

Seient L.

Occurrence--Twenty small mammal species were identified in senent

Li. (Table 6). Species from west (e.g., Pacific water shrew, shrew-mole,

Townsend's vole) and east (e.g., Muttall's cottqntail, yellow-bellied marmot, northern pocket gopher, western harvest mouse) of the Cascades occurred in this area of transition from niesic to xeric cor4itions.

According to Burt and. Grossenheider (1.9 6L4.), Ingles (1.965) and Maser and Storm (1.970), ranges of the dusky shrew, mountain beaver, creeping vole, Pacific jumping mouse and short-tailed and long-tailed weasels include all or part of seient Li.. These species, however, were not found in this senent.Nine additional species whose ranges include at least part of senent Li. were not recorded during this study (Table 1).

These species may possibly occur in this segnent, but many are known to occur only at elevations higher than that of the study area.

Relative abur4ance--Only one species, the deer mouse, was captured in all seven habitats, and it differed significantly in abundance among 30

TABLE6.Neazl tr4ex of abudacce (catures per 100 trap-ci.ts) values of ssa.U. nammalsn habitats izvenortedth seect 14 of the Coluahiaiver studywea.a :-aitat Dou1as Oak/ Shrub Fin ?o.erosa sock W.ilcw tilowMale Pine Oak 0.ssla i;-Rip (4)b (t) (z) (2) (2) (2) (2) Species or Gro (342)° (96) (252) (270) (2314) (168) (3814) 7aant shrew 0.7 1.1 0.5 Pacificwatershrew C owhrjd.e's shrew 0.6 1.6 0.14 Shrew-sole O9 Coast aole 1utt all'scottontail Snowshoe hare Townzond.'schipmur.k 0.2 1.6 Uow-bel2.ied sarmot California ouud. squirrel Weeterm ay squirrel Oou%las squirrel toz-thern f1ytnsquirrel Nbrthern pocket gopher 0.3 Western haest touse 0.5 Oeer sue 3.7 3.1 15.4 6.14 114.14 2540 26.3 3ushy-tailad. woodnat 0.3 0.8 0.5 Montane vole 1.2 1 .6 Townsend.' s vole 1 .3 tcng-ta.tled. vple 3 3 e e Total sanmals°° (MA) 12.9 14.3 13.9 6.3 15.7 27.5 26.3 lMk-deer nouse+vat shrew°°8.5 3.5 0.14 0.8 2.6 0.5 tnsecttvores 2.1 1.1 1.6 0.4 0.5 Lsecttvorss-vaantscrew 1 .5 1 .6 0.4 Mice 3.7 3.1 15.14 6.4 114.14 25.3 26.3 Mice-'eer souse 0.5 Tolee 6.3 1.6

azrteflsive samplingareas were sampled 2, 3 or 14 consecutive nights in fail 1974 and 3 or 14 consecutive nights in spring 1975, however, only the oate data. from the first 2 nights war, used, to calculate capttmee per 100 ap-.raghts because data from both seasons and. tnansive sampling areas of habItat were combined. bNbarsin parentheses equal intensive sampling areas of similar habitat. Ttbers in parentheses equal trap-nigh-ta thm'ing first 2 nights. ot canted, but was observed and/or Identified by sign in this habitat. ot oartzed. until third night. :\0trecorded. in intensive samplingareas,but was observed. in this habitat. Captz.ed in non-staard.ized traps only. Double character superscripts denote sIgnificant d.ifferences among habitat nean.s at the 5 percent level or less (analysis of variance).The results of the sean separation tests (Tukey' a w..prccedune) are d.ia.amed..Means uarscored by the same line are not signifIcantly d.iffar,nt.Means underscored. by the same d.oted. line differ yexactly w. sock Couglastn/ Oak,' RIp-Rap Orassland, Maple Oak Ponderosa Pine Willow Willow 26.3 25.0 15.14 114.14 6.14 3.7 3.1

Rock Douglas Fir! Oa/ Orassland Rip-Ran Maple Oak Willow Por4erosa Pine Willow 27.5 26.3 13.9 15.7 12.9 6.3 14.3 31

r.Bz6. Conttnued Dou1a.'/ Rock Caic/ a.o1e Grass.ar4 Oak Ri?-Rap ocd3resa ?izie Jti.olf 3.5 2.6 0.3 0.5 0. 0.0

ouia.s Ft Oac/ sock 3hb 'a1e t2.2.ow ?or4erosa Ptze Oak Gras1ath t.6 t.5 O.. 0.0 3.0 0.0 3.0

Rocc Dou1a3 t/ Oak/ Graas1a.. Oak ?oiderosa Pte ifl.flow 26.3 25.5 t5. t 6. 3.7

0ou1as fl.r/ oak/ Rock Willow Gr3.ss1a ap1e Oak ?or4eresa ?ire R±-Rap WU.icw 6.3 t.6 0.0 0.0 0.0 0.0 0.0 32

some of those habitats (Table 6). Siprisingly, rock rip-rap habitat

had. the highest mean IOA value for deer mice in this senerit. This sit-

ition also occurred in senents 5 and 6. It is not known what food.

soice supports such apparently high numbers of deer mice in this land.

form class, which bordered railroads or highways on one side, the river

on the other, and. is essentially devoid of vegetation.

Five species gnoups, total mammals, total mammals excluding deer

mouse and vaant shrew, insectivores excluding vagnant shrews, mice,

and voles, differed significantly in abundance among habitat (Table 6).

Significant differences in total mammal abundance among habitatswere

very similar to those of deer mice because deer mice were predominant in

all habitats except willow. Willow habitat had the highest mean 1OA

value for total niainsnals excluding deer mouse and. vaant shrew because

of the voles and other insectivores captied in willow. Except for

western harvest mice in assland habitat, deer mice were the only mice

in that species oup, and differences in mice abundance among habitats were very similar to those of deer mice. Vole abundance was gneatest in willow habitat which had. a ground. cover of moist litter and,a dense

ur4erstory of reed, canaxyass to provide food. and cover.

Deer mice made up most (7L-98 percent) of the total mammals captumed

in all habitats except willow (29 percent). Voles composed 53 percent of the total mammals capted in. willow habitat. Te.'art shrews, although present in this senent, decreased. in abundance probably due to the more xeric conditions in seinent L4. 33

Segment 5

Occurrence--Species richness was lowest in segment 5; oniy nine small rnaiiunal species were iden±ified (Table 7).

Eighteen additional species whoseranges are totally or partially inclusive of segment 5 (Burt and Grossenheider Ingles 1_965, Verts

1971, Maser and. Storm 1970) were notrecorded (Table 1). During this study, however, 11 of these specieswere found in segments other than 5.

Relative abundance--The deer mousewas captured in all five habitats (Table 7). Mean IDA values were highest in rock rip-rapand shrub willow, but there were no significant differences indeer mouse abundance among habitats. Rock rip-rap habitat had the highest abundance values for deer mice and nearly no vegetativecover; an identical sit- uation existed in both segments Land 6.

Because deer mice made up most of both total ma.mivals (9Li._100per- cent) and, mice captured tn all habitats,there were no significant d,ifferences in abundance of any of the speciesgmoups among habitats.

The predominance of deer mice, an early invader species c±disturbed areas (Dasinarin 1964:324W), and very low species richness may be due to filling of The Da.11es Pool (segment 5) in 1965 and resultingpermanent loss of ectensive amounts of diverse floodplain and. riparian habitat.

Segment 6

Occurrence--'1ineteen small mammal species were ideniified in segment 6. Of these species, 16 occurred in types of habitat sampled intensively (Table ). A road-killed white-tailed, jack rabbit '.as found. 34

TABLE 7.Mean. index of abn"diire (captures per 100 ap.-rjts) values of samnals La hai.tat.s iavazltorLecj La seea 3of the Coibia River stuarea. Habitat

Rockcli±'f/ RbbitbrushGrassland Sib ifl.ow i1tLlow Rock Rip-Ran (2)b (2) (1) (1) (2) Secies or Group (223)° (162) (102) (18) (3EL) Tu'ttall' a cottonta.il d e 3lack-tailad jack rabbit 'fellow-bellied tartot Ca.liforniaound squirrel Northern pocketo?her £ Great 3a.siaocket aouse 1.2 Westarr harvest aouse 0.3 jeer nouse 23.3 17.L. 30.0 25.0 30.5 3ushy-tai.ted. woodrat 1. .0 'Ibtajnmm1 (tMA) 23.3 18.6 30.0 25.0 31.3 TCMA-d.eerouse 1.2 1.3 Mice 23.3 18.6 30.0 25.0 30.3 M.tce-deermouse 1.2 0.3

3Thtensive saznplicg areas were sampled2, 3or consecutive oights La fallt97&a.r43 or consecutive nihta La sprtn t975 however, on.ly the capttze data from the first 2 rihtz were used to calculate captures per 100 tra'p-rlihts because data from both seasons and Lateri- sive saatplinareas of similar habitat were combined. bN=bereLa parentheses equal Later..si'te sampliaareas of similar habttat. La parentheses equal trap-nights during first 2 aights. Tot captured, 'out was observed and/or identifLed by sign La this habItat. ot recorded La thtenslv. sampling areas, brt was observed La this habitat. camtured in non-standard.i2ed sps only. Tot cantured until third iiht. fALI1.t 8. Mean index of abuiidancc (tures er 100 trap-nights) values of sivall wauuuals in t hutats inventoried in segiucot 6 of the Coluiubia Itiver study area. Rock Sage- Rabbit- Habitat 6rass- Cottonwood/ Itussian Species or Croup Rip-lIsp (192)C (1)b d Talus(288) (2) d Kock1iff/Ctassland (264) (2) 4 brush(252) (2) d brush(384) (2) 4 bitter-brush(384) (2) (384) (2)land 4 Willow (198) (2) 4 Marsh(312) (2) 4 Olive(l6) (1) e Yellow-belliedblack-tailedWhite-tailedNuitalt'slowiusend's cottontail jack Miarwot ground rabbit squirrel 4 4 4 4 4 d Western(reatOrd'sNorCalifornia the Ilasla in haXust pocket groundpocket Iaoti gopher mousesquirrel keuigai-uo rat 0.4 e 0.42.0 e 241.4 0.82.03.9 0.21.1 3.6 c 4.8 a 1.8 MontaneNuiwnyllussluy-LailedNoIleur rthemn mouse V&)1e tat gm saluopper woodrat mouse 33.3 32.6 1.0 29.4 0.7 28.0 3.0 8 0.33.4 0.3 0.41.5 071.3 4.2 d Mice-deerMIce44Totalhouse10t4A-dei ujojimouse uiuuse' uuianls (tUNA) 33.3 32.633.6 1.0 29.830.5 0.41.1 30.4 2.5 6.83.8 10.3 6.9 1.31.61.31.6 3.65.14.05.6 9.37.48.68.12.6 5.4549.63.6 tHuatbersSLmuupliuugthe capture inNnabe,-s parentheses areasIntensive data of (rout insimilar saumplingparentheses the habitat first areas2 were uuightsequal were combined. trap-nights weresawl)led used 2, to calculate captures equal intensive sampling during3 or 4 firstareasconsecutive 2 ofnights. similar nights in fall habitat. P 1974 and100 trap-nights because data 3 or 4 consecutive nights in spring from both seasons and 1975, however, oniyintensive SNotCCaptuI captured redHot in recorded uimit 11 thi in idintenstvti night. saupling areas,captured, but was observed and/or ideuutified muon s tamuda rd zed traps only. but was by sign inobserved this in this habitat. habitat. thC.) different.Theaa)OUblOTAhL results chaiacter of the 8. Continued. weansuperscripts separation Rockcliff/denote significant differences amongtests (Tukay's habitat meansw-procedure) at are diagramed. Means underscoredthe by 5 percentCottonwood/ thelevel same or line less are(analysis not significantly of variance). Rock Rip-Rap Talus33.3 Rock Itip-Rap 32.6Talus GrasslandRockcliff/ 29.4 Sagebrush 28.0 RitterbrushBitterbrush 3.4 RussianRabbitbrush Olive 3.0 MarshWillow 1.5 kabbltbrush Marsh 1.3 Cottouwood/Grassland Willow 0.3 Russian Olive Grassland 0.0 cc Russian Olive 33.6 9.6 Marsh33.3 8.1 Bitterbrush 30.5 6.9 Coltonwood/ Willow30.4 4.0 Rabbitbrusli 10.3 3.8 Sagebrush 9.6 Grassland 1.39.3 GrasslandRockcliff/ 6.81.1 Talus 1.05.6 Rock Rip-Rap 1.6 d&l Itock Rip-Rap Talus Sagebrush Grasslandltockcliff/ Marsh 25 Rabbitbrush Russian Olive Cot tonwood/ Willow Grassland 0.0 Ce Marsh33.3 7.4 llitterbrush 32.6 6.9 Russian Olive 30.4 5.4 Rabbitbrush 29.8 3.8 Cottonwood/flitterbrush Willow10.3 3.6 Sagebrush 2.58.6 Grassland 6.81.3 GrasslandRockcl I ff1 0.45.4 Talus 0.05.1 Rock Itip-Rap 0.01.6 37

on the ashinon shore in rabbitbrush habitat. Because of concentrated

a'icultural practices and rodent control proaras in the white-tailed

jack rabbit' s optnu habitat, this species has declined in numbers and

is considered a rare mammal in Washington (Lauckhaxt 1970). The short-

tailed weasel was observed in aicultural lands, an area not spec if

cally sampled. Skulls of the long-tailed vole and vaant or dusky

shrew (B. J. Verts 1978, Oregon State University, personal communication)

were found in barn owl (o alba) pellets collected at a nest site in

marsh habitat on the Irrigon Wildlife Nanagement Area (RN 283-286).

Addltional species found in the pellets (e.g., Great Basin pocketmouse,

Ord's kangaroo rat, northern pocket gopher) indicate that the owls

foraged in nearby shrub-steppe habitats.However, the nest location

and habitat requirements for the long-tailed vole and Sorex suggest

both were captured in marsh habitat.

Ten species, whose ranges include at leastpart of segnent 6

according to Burt ar4 Grossenheider (1961.i.), Ingles (1965),and. Verts

(1971), were not recorded in thissenent (Table 1). Absence of preferred habitats and. sDecies rarity may excludemany of these species from the study area in senent 6.

Relative abundance--The deer mouse was captured n all habitats

except Russian olive, the only habitat in the entire studyarea where

deer mice were not captured. As in segnents Lk and 5, deermouse bA

values were highest in rock rip-rap habitat. Deer mouse bOA values were not significantly different anong bitterbrush, rabbitbrush,cottonwood/willow, marsh, gnassland,and. Russian olive habitats, but were

significantly lower than OA values of deer mice in rockrip-rap, talus, 38 rock clisland, and sagebrush habitats by at least a factor of 3 (Table 8). Loose, sandy soil arid aridness of 'citterbrush, rabbit'orush, and assland habitats may be factors limiting deer mice abundance in these

habitats.Kritzman(t97L.)and O'Farrell(1975),working along an eleva- tiona]. adient in the shrub-steppe region of eastern Washington, found deer mice less abundant on arid, desert floor than at higher elevations. Because deer mice prefer rocky areas arid, cooler soil temperatures for shallow buows, itzman concluded the deep, loose, dry soil cf the desert floor may be a limiting factor in deer mice distribution and density.Greater soil moisture and, moisture availability at higher

elevations (31 deer mouse captures per 1.00 trap-nights at1,070 m) compared to the desert floor (three deer mouse captures per 100 trap- nights at 150 m), led. 0 'Farrell to conclude that lack of succulent vegetation or free water at lower, more arid, sites possibly limits deer mice abundance.Probably both edaphic conditions and available moisure in bitterbrush, rabbitbrush, and.assland habitats are important factors restricting abundance of deer mice. Low deer mouse abundance in cottonwood/willow and marsh, and no deer mice in Russian olive habitat is possibly the result of interspecific competition.Competition for similar resources may exist in

cottonwood/willow habitat between deer mice and western harvest miceand in marsh habitat between deer mice and both- western harvest mice arid.

house mice.Sheppe(1.967)for4 each species, deer mice and house. mice, most abundant in places where the other. was least abundant and suggested mutual ei1uzion as the possible reason.Competitive exclusion of deer 39 mice by house mice was found in additional tests (Sheppe 1967).

Irrigation runoff canals were established through the Russian olive sampling area and. produced a dense, lush vegetative understory.

Surprisingly, deer mice were not caught in this habitat. Overwhelming direct competition from other opportun±stic foragers, western harvest mice, house mice, and particularly Norway rats, may exclude deer mice from this area. Western harvest mice, house mice, and deer mice, although low in number, were present in Russian olive habitat along the

McNa.ry Reservoir of the Columbia River in Washing-ton; Norway rats were not captured (Asherin and Claar 1976). On Miller Sands, a island of dredged material in the lower Columbia River (RN 24, segmient2), four

Norway rats and, one deer mouse were captured in 1, 5LJi. trap-nights of effort (1oodwa.rd-Clyde Consultants 1978). A subseq,uent study on Miller

San produced 20 Norway rats and no deer mice in 7,328 trap-nights of effort (Crawford. and Edwards 1978). Interspecific competition may limit deer mice abundance, however, low abundance estimates may simply reflect habitat preferences of deer mice.

Significant and non-significant differences among habitats for total mammal and. mice IOA values were the same as those for the deer mouse (Table 8).

Mice were predominant in seent 6.They composed 91-100 percent of the total mammals captured in all habitats except Russ±an olive(56 percent).

Gecaphic Distribution

The deer mouse was the only species captured in all seients of L.0

the study area. California gmound squirrels were also widely distrib-

uted., occurring in al]. segments (Table 1) and thus ecbending their

known range (Armstrong 1962, Burt and Grossenheider t9624, Ingles 1965,

Yerts 1971) eastward into segments 5 and 6.

Mice ware captured. in all segments, and differences in abundance were significant between segments 5 and. 2 and between 5 and. 1 (Table 9).

Nice, essentially all deer mice, were most abundant in segment 5, where they comprised. 99 percent o± the mammals captured. In segments 1 and 2 mice were less predominant, 22 and 60 percent of the total mammals captured, respectively. Insectivores and voles accounted for most of the remainder. Mean bA value for mice was lowest ifl segment 1, whereas insectivore and vole mean IDA values were highest in that segment (Table

9).

Mean IDA values for deer mice were not statistically different among segments, however, the highest mean (segment 5) was nearly six times gm'eater than the lowest mean (segment 1)(Table 9). Deer mice, which were nearly the only mice captured in the first five segments, increased in &oundance from segments 1 to 5 and then decreased in segment 6. The same pattern was evident for the percentage of deer mice in the total mammal catch.

The increase from west to east in this gmanivorous and omnivorous species may be associated with increasing seed availability, eastward.

Due to higher vegetative biomass in the west, seed production isno doubt gmeater there than in the east. Long owing seasons, rapid germination, dense vegetation, and d.eeD litter in the west could make seeds more difficult to obtain than in the east, where the opposite L.1

TABLE 9.Mean index of abundance (captes per 100 traD-nights) values of amall mammals in seiients of the Oolumaoia River study area d.uringt971.4, 1975. Se'aent

Species or Group 1. 2 3 5 6

a. Insectivores, 12.3 .2 Li..8 0.8 0.0 0.0 Vaant sh.rew 9.6 3.9 L4.7 0.3 0.0 0.0 C Insectivores - vaant shrew 2 .7 0 .2 0 .1 0.5 0 .0 0.0 Mtced 4..6 7.2 lLi..1 13.5 25.516.5 Deer mice L..3 7.2 1LL..1 13.525.2 13.3 Mics-'jeermouse' 0.3 0.0 0.0 0.1 0.3 3.1 VO8S 3.L. 0.6 1.8 1.2 0.0 0.1 Total inaa.s (TOMA) 20.6 12.1 20.7 16.1 25.7 17.1 TOMA-deer rriouse+vaant 6.7 0.9 1.9 2.3 0.5 3.8 aSerscrjptsdenote significant differences among seient means at the 5percent level or less (analysis of variance).The results o± the mean separation tests (Tukey's w-procedure) are diaranied.Means underscored by the same line are not significantly different.Means underscored by' the same dotted line differ by exactly w. 1 3 2 5 6 12.3 L3 Lk.2 0.8 0.0 0.0

3 2 Li. 5 6 9.6 4.7 3.9 0.3 0.0 0.0 C1 4 2 3 5 6 2.7 0.5 0.2 0.1 0.0 0.0

5 3 2 1 2).) 10.) 1 13.) 7.2 .0

e6 1 4 3 2 3.1. 0.3 0.3 0.1 0.0 0.0

3 4 2 6 5 3.4 1.8 1.2 0.6 0.1 0.0

6' L 3 2 5 6.7 3.8 2.3 1.9 0.9 0.5 conditions occur.

The increase in deer mice abundance might so be attributed to reduced habitat diversity in the east. Loss of riparian and floodplain habitats caused by reservoir construction and filling and the frequent

inundation of remaining riparian areas due to dam operations drastically reduced shoreline vegetation and diversity in the Bonneville Pool

(segmer.t Li.), John Day Pool (segment 6) and particularly TheDaIJ.es Pool

(segment 5). This disturbance and resulting reduction in vegetative diversity may account for the increase in deer mice, an early invader species, in these disturbed areas.

Small mammal richness was lowest in segment 5 (nine species) and is possibly associated with reduced riparian vegetative diversity caused by the dams and their operation.

The decrease in deer mice abundance in segment 6may be riated to habitat selectivity by deer mice and possibly to the combined effects of interspecific competition between deer mice and. other anivorous and. omnivorous small mammals. Deer mice preference for shallow, rocky soils (critzman 1971k) with 'eater available moisture and moderate temperatures (O'Farrell 1.975) limits their abundance insortie habitats in segment 6. Great Basin pocket mice, Ord's kangaroo rats, western harvest mice, and. oarticularly house mice and Norway ratsmay compete with deer mice for similar resources, thus suppressing deermouse abundance in. habitats where these species occur together.

Mice excluding deer mice were signifoantlymacre abundant in segment 6 than all other segments except 1 Arid, and semi-arid conditions and. deep, sandy soils are PrefezTed by the heteromyids (ingles 413

1965, :itzman 1974, O'Fefl 1975) andoccur in the eastern portion

of segment 6.

Insectivores were captured only in the first four segments and. geognaphic differences in insectivore and vagmant shrew abundance were auoarent (Table 9). Insectivores, vagnant shrews, and insectivores excluding vaant shrew were significantly more abundant in segment I than the other segments. Insectivore abundance decreased from west to east. A positive relationship appears to exist between insectivore abundance and mosture. Annual precipitation in segment 1 is nearly 70 percent more than in segments 2 and 3, four times as much as segment 4, and 'eater than segments 5 arid 6 by at least a factor of 10 (Rud.d. 1962,

Lynott 1966). High productivity and biomass accurnU.ation due to the uniformly wet and mild climate of the coastal Picea sitchensis zone

(Franklin and Dyrness 1973) sustain large numbers of invertebrates and microorganisms that feed on this vegetetive biomass and its remains

(Ricklefs 1973). A more moist and less extreme climate and preferred foods in abundance mes segment 1 more suitable for insectivores than the other segments. There were no significant differences in abundance of insectivores and vagnant shrews betweensegments 2 and 3- This was not surprising because vegetation and, climate are so similar in segments 2 and. 3 arid many of the same types of habitat were saaDled in both segments. Insectivore and. vagmant shrew mean bA values in segments

4, 5 and. 6 were significantly lower than segments 1, 2 and.3. This d.i±'ferenc is rir.cially attributed to the dri3r 1 imatean ack c' habitats with rich vegetative cund cover and deep, moist litter in the eastern segments. The vagmant shrew, according to Burt and. 4.

Grossenheider (196Lt.) and Hall and Kelson (1959), occurs in segments 5 and. 6, 'but apparently in extremely low densities or in areas not sampled during this study.

Voles were captured in all segments except 5. Segment 1 had significantly 'eater vole abund.ance than segments 5 and. 6. Vole abundance decreased front west to east. This decrease corresponded with the west to east moisture 'ad,ientasdid the decrease in insectivore abundance. Heavy precipitation and long owing seasons in western segments of the study area (Ruciä. 1962) produce more vegetative bioniass throughout the year that supports a larger nuzirber of voles than eastern segments.

The higher vole abundance in the west may also be related to greater cover provided by the dense vegetation.Zimmerman (1965), Batzli (1968), and. Shure (1970) found Microtus abundance greater in areas with higher density of herbaceous cover. Maser and Storm (1970) and Goez-tz (1959,

19614) found generally that most voles (Microtus spp.) prefer heavy ground cover of mixed grasses, sedges, and forbe in rparian or moist areas.

Although geographic differences in abundance were evident for mice, insectivores, and voles, total mammal abundance was not statistically different among segments. It was probably coincidental that indices of total mammals were similar in all segments (Table 9), whereas voles and, insectivores decreased and. mice tncreased from west to east, because capture probabilities are not equal for these different groups of species.

It is interesting to note, however, the apparently related changes that occurred across this ecological gradient. In segment 1, relative to the other segments, habitat disturbance was low, and climate was less extreme and variable. Specialists such as insectivores and herb-

ivores (voles) were more abundant, and the omnivorous deer mouse, a generalist and early colonizer, was less abundant. Further eastward. along the Columbia River, habitat disturbance increased, and, climate became more extreme and variable.Specialists decreased, and the deer mouse Lncreased. In segment 5, habitat disturbance appeared gm'eatest, specialists declined, and deer mice were most abundant. Mice other than deer mice increased in segment 6.Granivorous specialists such as

the Great Basin pocket mouse, Ord's kangaroo rat, and western harvest

mouse have adapted to this more severe environment (Odum 1971., Ingles

1.965). Deer mice decreased in abundance possibly due to the lack of

preferred habitat and competition with specialists and other generalists.

Numerous species, whose ranges included the general area of the

study according to various authors, were riot recorded during this study

(Table 1). These species may not have been found for several of the

following reazons (1) sampling methods were not intensive enough to

capture the more elusive, rare, or low density species; (2) certain

species do not occur at low elevations or in riparian areas of the Cal-

uinbia River; (3) some species may inhabit areas or habitats not sampled;

(L.)some possibly no longer occur in the study area; or (5) some may

never have been in the study area. Present distribution and occurrence

of small niamzaals along the Columbia R±ver, however, are not drastically different than when Bailey (1.936) did bis survey and Hall arid Kelson

(1.959) compiled their information. 46

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1958. The removal method of population estimation. J. Wild.l. Manage. 22(1):82-90. APPTDICES AreaSamplingTABLE No. A. Intensive sampling areasSegment established in the Columbia River study Shore Habitat Location area, 1974-1975. Elevation 21 11 Oregon TidalBeachgrass marsh RN 5,7, E.N.W. H. 11 W. , S., 35,3. 6,T. T.. 8 N., 8 N., Near sea level 3 1 Oregon Tidal marsh RN 7, N.W. R. 10 W. , S. 6, T. 8 N., Intertidal 45 1 WashingtonOregon BeachgrassAlder Ft.RM7,W.,S.6,T.8N., Canby State ParkR.H. 10 W. NearIntertidal sea level 76 1 Washington TidalAlder marsh Ft. Canby State Park Near sea level 1 2 Oregon Tidal marsh RN 21, NE. S. 16, T. 8 N., R. 8 , S. 20 & W.S.W. , Intertidal 32 2 Oregon Tidal shrubSitka willow RNRM 25,26, S.E.N.E. *, S. 18,H. 8 W. , S. 12, P.T. 8 N., Intertidal 4 2 Oregon Cottonwood spruce RN 65, N.E. H. 27 W. , S. 7, T. 7 N., Intertidal 65 2 Oregon ReedWillow canarygrass RN 71,75, S.E.E. 4, S. 13,R.2W. T. , S. 26, T. 7 N., 6 N., 4.6-8.21.5-3m m 7 2 Oregon Cottonwood/willow RM 7)4, N.W. R.2W. , S. 12, >4.6m 8 2. Washington Tidal marsh RN 23, W. 4, S. 4, P.H.R.2W. 8 W. 9 T.N., 6 N., Intertidal13-4.6m AreaSamplingTABLE No.A. Continued. Segment Shore Habitat Location Elevation 9 2 Washington Tidal Sitka RN 37, N.W. , S. 35, P. 9 N., 15 2 Island Tidal marsh spruce RN 30, R.IL 67 W. -, S. 24, T. 9 N, Intertidal 1716 2 Island Tidal shrubmarsh RN 32, H. 6 N.W.N.W. *, S., S. 19, P. 19, T. 9 N.,9 N., Intertidal 18 2 Island Tidal Sitka willow RN 36, R. 6 S.W.W. , S. 24, T. 9 N., Intertidal 19 2 Island Cottonwood spruce RM 7Li, IL. 6 S.W.W. , S. 7, P. 6 N., Intertidal 20 2 Island Cottonwood/willow RN 75, H. 1 W.S.W. , S. 7, T. 6 N., 3-4.6 in 22 2 Island Reed canarygrass RN 75, H. I W.N.W. , S. 18, P. 6 N., 3-6.1 m 1 3 Oregon Cottonwood RN 89, R. 1 Ii.W. , 5. 22, P. 4 N., 1.5-.3 m 2 3 Oregon Cottonwood/willow RN 91, R. 1 W.N.E. , S. 34, T. 4 N., 4-5.2 m 3 3 Oregon Ash/willow/cotton- RN 91, R. 1 N.W. , S. 34, T. 4 N., 3-4.6 m 4 3 Oregon Reed canarygrass wood RM 97, R. 1 N.W.W. , S. 26, P. 3 N., 3-4.6 m 65 3 OregonOregon ShrubWillow willow RN 130, R. 1 E.W. S.S.W. -, -, S. 20, P. S. 21, T. 1 N., 1 N., 4.6-6.1 in 7 3 Oregon Ash/willow/cotton-wood Rm 130, H. 5 1. E. N.E. , S. 29, T. 1 N., SamplingTABLE A. Continued. Area No. 9 Segment 3 Washington Shore Cottonwood Habitat RN 120, N. fr, Location S. 14, T. 1 N., Elevation 10 3 Washington Cottonwood/willow RN 123, H. 3 E. S.E. , S. 17, T. 1 N., 7.6-9.1 m 11 3 Washington Ash/willow/cotton- RN 91, H. 4 N.W.E. , S. 35, T. 4 N., 7.3-9.1 m 12 3 Washington Willow wood RN 90, H. 1 W.SW. , S. 26, T. L1' N., 3-4.6 in 13 3 Washington Shrub willow RN 123, H.R. 1 4 E.w. S.E. , 3. 17, T. 1 N.., 5.8-6.13-4.3 m in 1514 3 IslandWashington CottonwoodReed canarygrass RN 125,123, R.4E. S.E.S. fr, -i-, S. S. 21, 17, T. T. 1 N.,1 N., 6.8m 16 3 Island Willow RM 125, R. 4 E. N.E. , S. 21, T. 1 N., 6.1-6.76.7-7.3 rnin 1817 3 Island ReedShrub canarygrass willow RNRN 125, 126, H. 4 E. W.N.E. fr, S., S. 22, 21, T. T. 1 N.,1 N., 5.5-6.1 m 19 3 Island Cottonwood/willow RN 124, H.H. 4 4 E. N.tJ. , S. 20, T. 1 N., 5.5-7.66.4-7.9 m m 1 4 Oregon Willow RN 161, R. 9 E. N.E. , S. 34, T. 3 N., 23.8-23.9 in 32 4 Oregon WillowDouglas fir/maple RN 161, B. 9 E. S.W.N.W. , S. 35,35, P.T. 3 N., 23.5-24.1 m 4 4 Oregon Oak/Ponderosa pine RN 177, H.H. 12 9 E.S.W. , S. 32, T. 3 N., 27.4-6145.7-122 ii m A) AreaSamplingTABLE No. A. Continued. Segment Shore Habitat Location Elevat:lon 5 ii Oregon Oak RN 178, S.W. , S. 33, T. 3N., 6 4 Oregon Grassland RN 178, R. 12 E.SW. , S. 33, P. 3 N., 30.5-61 in 7 4 Oregon Shrub willow RN 179, R. 12 S.E.E. , S. 33, P. 3 N., 67.l-73.2m 8 Li- Oregon Rock rip-rap RN 180, R. 12 S.W.E. , S. 34, T. 3 N., 23.2-25 m 10 Li- Washington Oak RN 162, R. 12 N.E. --, S. 26, T. 3 N., 28.9 in at top 11 Li- Washington Douglas fir/maple RN 162, R. 9 E. N.W. , S. 26, T. 3 N, 24.4-30.5 in 1213 4Ll Washington GrasslandOak/Ponderosa RNRN 178, 176, H.R. 912 E. N.S.W.E. , +, S. S. 32, T. 25, P. 3 N.,3 N., 36.6-6148.8-122 in in 14 Li- Washington Willow pine RN 179, R. 11 N.E. , 5. 33, P. 3 N., 36.6-97.6 m 15 4 Washington Willow RN 183, H. 12 N.W.E. , 5. 7, T. 2 N., 22.9-27.4 m 16 4 Washington Rock rip-rap RN 177, R. 13 E.N. , S. 36, P. 3 N., 23.8-25.3 m 1 5 Rabbitbrush RN 198, R. 11 N.E. , S. 24, T. 2 N., 30.5 m at top 2 5 Oregon Rockcliff/grass- RN 203, R. 14 N.W.E. , S. 22, P. 2 N.., 122 m 3 5 Oregon Shrub willow land RM 210, H. 15 S.E.E. -, S. 2, P. 2 N., 79.3-91.5 in 4 5 Oregon Willow RN 211, R. 16 E.S.W. -, S. 1, T. 2 N., --61 rn '61 m TABLE A. Continued. AreaSam p11No. ng 6 Segment 5 Oregon Shore Rock rip-rap Habitat RN 208, N. *, Location S. 9, T. 2 N., Elevat :1 on 7 5 Washington Rock rip-rap RN 207, H. 16 N.W.E. , S. 7, T. 2 N., -61 m 8 5 Washington Rabbitbrush RN 210, R. 16 E. , S. 35, P. 3 N., .-61 m 51.8-59.5 in 91 65 WashingtonOregon TalusRockcliff/grassland RN 211,222, R. 16 E.N.W. j, , S. 21,36, T. T. 3 N.,,N., 68.6-106.7 m 2 6 Oregon Hockcliff/grass- RN 227, H. 18 N.W.E. -, S. 6, P. 3 N., 122-182.9 m 3 6 land RN 227, H. 19 N.E.E. , 5. N., 182.9-243.9 4 6 Oregon BitterbrushSagebrush RN 273, R. 1926 E.LW.E. -j, S. 31,6, T.T. 3 5 N., 88.4-91.591.5-137.2 in in 65 6 Oregon GrasslandRabbitbrush RN 276,274, R. 26 N.N.W.E. *, S., S. 20, T. 5 31, T. N.,5 N., 85.4-88.4 in 7 6 Oregon Cottonwood/willow RN 275, H. 26 S.E.E. , S. 19, T. 5 N., 83.8-86.9 in 8 6 Oregon Ivlarsh RN 276, R.R. 26 26 E.N.E. , S. 29, T. 5 N., 80.8-82.380.2-81.7 m in 11 9 6 WashingtonOregon RockRussian rip-rap Olive RNRN 283, 279, R. 26 E.N.W.N. --, S., 17, T. 5 S. 22, P. N.,5 N., 85.4 in 12 6 Washington Bitterhrush RM 281, H.R.26 27 E. N.E.E. , 5. 13, T. 5 N., 88.4-89.983.8 in in AreaSamplingTABLE No. A. Continued. Segment Shore Habitat Location Elevation 1413 6 Washington GrasslandRabbitbrush RNRN 281, 281, R. 26 S.E.E.N.E. -, , S. 12,13, T.P. 5 N.,N., 85.4-88.4 in 15 6 Washington. Marsh RM 280, R. 26 N.E.E. , S. 11, P. 5 IL, 82.3-85.4 m 16 6 Washington Talus RN 230, R. 26 N.W.E. , S. 34, T. 3 N., 80.2-81.7 m 17 6 Washington Rockcliff/grass- RN 230, R. 19 N.E. , S. 33, P. 3 N., 85.4-122 in 18 6 Washington Sagebrush land RN 229, R. 19 S.E.E. , S. 20, P. 3 IL, 122-182.9 n 19 6 Washington Cottonwood/willow RN 280, R.H. 19 26 E.N.W. fr, S. 14, T. 5 N., 85.4-97.680.8-82.3 m m 'FABLE B. Meanand index spring of 1975abundance in segment values (captures 1 of the Columbia River study area.' per 100 trap-nights) in small mammal intensive sampi ing areas inventoried during fall 1974 Oregon Washington Oregon Intensive Sampling Area / Season Orcgoii Washington Oregon Washington Species or Group Bcachgrass(96) 1bS.A. (96) Sp I Beachgrass(96) (96) FS.A. 5 Sp Tidal Marsh (60) (60) S.A.F 2 Sp Tidal Harsh (60) (60) FS.A. Sp 3 Tidal Marsh (78) (78) FS.A. 7 Sp (78) S.A.F 4 Alder (96) Sp (96) (96) FS.A. 6 Alder Sp PacificDuskyVagrant shrew watershrew shrew 10.6 1.8.3 1 13.0 6.1 20.4 16.7 1.9 14.4 19.9 5.5 10.6 4.2 1.1 8.7 d 6.7 BrushCoastShrew-moleTrowbridge's rabbimole t shrew 0.9 e 1 è 1 e 1.9 47 1.13.3 1.12.0 2.2 0 Douglas'CaliforniaTownsend'Snowshoe squl harea groundchipmunk rrel squirrel f f 1. e CreepingTownsend'sLong-tailedI)eer mouse vole vole vole 2.2 5.9 d 6.51.1 3.35.4 3.7 15.3 3.7 8.8 13.0 1.9 4.2 1.48.9 1.1 d 11.5 1.1 10.6 2.0 TotalShort-tailedLong-tailedPacific Mammals jumping weasel weasel mouse 1.9 1.9 1.9i . 1.4LI 1.1 MiceTOMAInsectivores - Deer Mouse - Vagrant+ Vagrant Shrew Shrew (TOMA) 13.711.5 0.9 15.3 9.41.1 14.121.7 1.17.6 14.8 6.13.3 22.227.8 1.97.4 18.522.739.4 1.9 14.426.812.5 19.913.034.7 12.2 5.52.5 10.620.9 1.4 11.1 4.78.95.8 20.4 7.88.9 11.913.0 3.1 10.917.614.131.3 MiceaintejisiveVoles - Deer Mouse sampling areas were sampled 2, 3 or 4 consecutive nights in fall 2.2 5.9 6.51.1 3.35.4 3.7 197419.0 and 3 or 4 8.81.9 13.0 1.9 1.15.51.4 8.91.4 1.1 11.5 1.1 11.7 2.01.1 CN(nnl)el.S infirst parentheses 2 nights were used to calculatefall 1974; Sp= spring 1975. equal trap-nights (luring first 2 nights. captures per 100 trap-nights. consecutive nights in spring 1975, but only the 1Cap1uredCaptured in non-standardized traps only.captured, but was observed and/or identified by sign afterin saml)I second ing night. area. TADLE C. Small1 of mammalthe Columbia captures River per study 100 area.atrap-nights and species diversity index values by trap station type in habitats inventoried in segment Beachgrass (384)C Uahitat' / Trap Station 'fype Tidal Marsh (396) Alder (366) DuskyVagrantSpecies shrew orshrew Group 11.8 1 10.0 0.8 2 6.7 3 0.39.5 12.8 1 16.7 2 12.5 0.8 3 14.0 0.3 dX 0.7 1 4.45.3 2 0.99.6 3 0.62.05.2 X CoastShrew-moleTrowbridge'sPacificSnowshoeDrush mole water rabbit hare shrewsitrew 0.7 0.8 0.20.3 e 0.8 0.3 2.9 0.92.6 2.63.50.9 3.01.2 e Townsend'sCaliforniaDeerDouglas' mouse chipmunkgroundvolesquirrel squirrel 3.5 4.2 3.3 3.7 f 1.9 0.84.2 1.72.5 0.82.9 0.75.8 9.6 0.93.5 0.56.30.2 de Short-tailedPacificCreepingLong-tailed jumping vole voleweasel mouse 0.7 2.5 4.2 2.5 3.2 0.81.72.5 13.3 0.8 0.60.56.3 0.9 0.3 g TotalI,ong-tailedf4A majiunats - deer weasel mouse + vagrant shrew - (TOMA) 16.7 1.4 18.3 4.2 14.2 4.2 16.4 3.3 17.9 3.2 27.5 6.70.8 17.532.5 26.0 9.10.3 11.6 5.1 24.6 9.6 21.9 8.8 11.919.4 7.8 VolesMiceInsectivores - deer mouse vagrant shrew 12.5 0.73.5 11.7 2.54.21.7 4.23.36.7 10.3 2.53.70.8 12.8 3.21.9 16.7 3.30.85.0 14.215.0 0.83.31.7 14.6 0.50.67.23.4 4.30.75.83.6 10.514.0 0.98.8 17.5 0.93.57.9 0.50.36.66.8 CNumhersbintetisiveaijitensiveSpecies diversity samplingfirstin parentheses 2 indexnights areas were equalwere used trap-nisampled to calculateguts 2, 3during or 4captures consecutive first 2 iiights.per 100 nights trap-nights. in fall 1914 and 3 or 4 consecutive nights samplingin areas of similar habitat combined; seasons combined. 0.84 1.21 1.05 1.03 0.79 1.29 1.36 1.15 spring1.37 1975, but only the 1.61 1.59 1.52 eNOdCaptUrcdCaptured after second in non-standardized night. traps only.captured,recorded but in wasintensive observed sampling and/or areas, identified but was by observed sign in this in thishabitat. habitat. FABIJ U. Mean index of abundance values (captures per 100 trap-nights) and spilug 1975 in Segment 2 ot the Columbia River study Oregon Oregon Washington n smallIntensive mammal Sampling intensiveIsland Area sampling/ Season areas inventoried during fall 1974 Oregon Island Oregon Washington Island Species or Cintip S.A.(60)L F MarshTidal 1-Ilk (6(1) Sp S.A. 1-Ut)(60) F MarshTidal (60) Sp S.A.MarshTidal 8 F S.A. 16MarshTidal F Tidal(60) ShrubF S.A.Wi 1 low 2 (18) Sp Tidal ShrubS.A. 17Willow (96) F Tidal(60) F S.A.Spruce Sitka(60) Sp3 Tidal Sltka S.A.Spruce 9 (78) P Tidal SitkaS.A.Spruce 18 (51) F Townsend'sDuskyllrushJrowbridge'sPacificVagrant shrew rabbit watershrew mole shrew shrew 5.6 18.5 1.4 1.9 (96)(66)0.92.2 3.2 3.33.7 1.9 2.5 6.7 IleerNorthernCaliforniaTownsend'sEastern mouse cottontati flying chtpiiiunkground squirrel squirrel 1.4 e d e ae NorwayCreepingLong-tailedTownsend's rat vole vole vole 1.4 5.6 d 7.4 10.2 7.2 1.9 19.9 e 16.2 d 20.8 8.3 'lutalPacificlOMAlong-tailed Mammals jumping weasel mouse - Deer Mouse (TO14A) + 8.31.4 25.9 1.9 8.8 12.0 10.4 1.9 3.2 26.8 18.0 23.3 14.9 MiceVolesInsectivores Deer Mouse - Vagrant Shrew Vagrant Shrew 5.61.4 18.5 7.41.9 7.41.4 10.2 1.9 7.22.23.1 1.9 3.2 19.9 3.37.0 16.2 1.9 20.8 2.5 8.36.7 bNot 2 nights were used to calculate capturesall per intensive sampling areas were sampl ed sampling areas were Sampled 2, 3 or IOU trap-nights.during4 consecutive the spring sampling nights in fall 1974 and period; F= f13 or 1 4 consecutive nights 1974; in spring 1975, hut only the first £Notdaptt*tejCapturedNuiat)ers in non-parentheses standardi equal zed captured, but was observed und/or identified after second night. trapstrap-nights only. during first 2 nights. by sign in sampling area. Sp= spring 1975. lABLE I). Coot inued. Oregon Island Oregon intensive Sampling Arca / Oregon seasonb Island Oregon island Reed CottonwoodF S.A. 4 CottonwoodS.A. 19 F F WillowSA. 5 Cottonwood/F S.A.Willow 7 Cottonwood/S.A. 20Willow F Canarygrass F S.A. 6 Reed Sp Canarygrass S.A. 22 F DuskySpeciesVagrant shrew or shrew group (96) (96) 2.0Sp (96) 9.4 (96) 5.0 (96) SpLi (96) 4.1 (96) Sp1.1 (96) 3.0 (96) 7.0 14.1(96) (78) 5.3 Pacific water shrew t - BrushTownsetui'Trowbridge' rabbit a moles shrew C e eC e DeerNorthernCallTownsend'sEastern fornmouse cottontail flying chipmunk squirrel i a ground qui rre 1 1.1 2.0 d 3.2 20.4 31.1 10.7 1.1 O9 d Townsend'sNorwayCreepingLong-tailed rat vole vole 1.1 1.11.9 0.9 e 3.3 1.1 2.2 TOMATotalPacificLong-tailed Mammals j umping weasel mouse - l)eer Monad + Vagrant Shrew (TOMA) 1.2.2 1 3.07.0 9.4 8.2 22.4 0.9 35.2 15.2 3.3 5.21 . 1 8.0 16.314.1 2.2 5.3 VolesMiceNiceinsectivoresInsectivores - Vagrant Shrew Denr Mouse 1.1 3.02.0 9.4 5.03.2 20.4 0.91.1 31.1 4.1 10.7 3.31.1 1.13.0 0.97.0 2.2 5.3 liNotaintensive samplingfirst 2 nights areas were were used sampled to calculate 2, capturesall intensive per sampling areas were sampled during during3 or 4 consecutive nights in fall 1974 100and trap-n:ights. the spring sampling period; F= 3 orfall 4 1974; Sp consecutive spring 1975. nights in spring 1975, but only the eNOdCapt1redCNt1IIi)erstCapturcd in inparentheses non-standardized equal trap-nights traps only. captured, but was observed and/or identified after second night. first 2 nights.by sign in sasipling area. TABLE E. 2Small of the mammal Columbia captures River studyper 100 area.' trap-qights and species diversity index values by trap station type in habitats inventoried in segment Habitat b / irap Station type Species or Group 1 Tidal Marsh 2 3(402)C X Tidal Shrub Willow1 (174) 2 3 X Tidal Sitka 1Spruce (249) 2 3 X Townsend'sTrowbridgePacificDuskyVagrant shrew watershrew mole's shrewshrew 6.4 0.81.6 0.85.0 0.54.3 1.5 3.7 1.7 1.0 1.3 2.76.7 1.23.0 e DeerNorthernCaliforniaTownsend'sEasternBrush mouse rabbit cottontail flying chipmunkground squirrel squirrel e de NorwayCreepingLong-tailedTownsend's rat vole vole vole 0.63.8 5.6 6.7 0.25.4 1.9 0.6 16.2 14.7 20.0 17.0 d TOP4ATotalLong-tailedPacific mammals -jumping dcci weaselmouse mouse (TOMA) + vagrant shrew 10.9 6.40.6 2.41.68.70.8 12.5 0.8 10.7 1.00.3 1.5 5.6 2.4 18.2 1.0 16.0 29.3 2.7 21.2 1.2 e MiceSpeciesVolesInsectivoresInsectivores - dcci- diversity mouse - vagrant index shrew 0.843.8 1.030.86.3 0.880.86.75.8 0.920.35.60.54.9 1.5 0.641.93.7 0.60.211.7 16.2 0.421.02.0 14.7 0.281.3 20.0 0.822.79.3 17.0 0.511.24.2 CNumt,ersbintensiveaijitensive in samplingparenthesesfirst 2 nights were used to calculate captures per 100 trap-nights. sampling areas of similar habitat combined; seasons combined. areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only the dCapttlredeNO Captured in iion-standardized traps only.recordedcaptured, in but intensive was observed sampling and/or areas, identified but was byobserved signafter in in this secondthis habitat. habitat. night. equal trap-nights during first 2 nights. TABLE Ii. Continued. Cottonwood (288)C Willow (192) Iiabitat' / Trap Station Type Cottonwood / Willow (288) Reed Canarygrass (270) VagrantSpecies shrew or Group 3.7 1 4.4 2 3.3 3 3.8 1 4.2 1 3.3 2 1.7 3 3.1 I 3.7 1 2.2 2 2.2 3 2.7 X 6.9 1 9.5 2 10.7 3 9.0 Townsend'sTrowbridge'sPacificI)usky shrew watermole shrew shrew e f California'rownsend'sNorthernEasternBrush rabbit cottontail groundflyingchipmunk squirrel gCe e g Townsend'sCreepingLong-tailedDeer mouse vole vole 0.91.9 1.12.2 0.40.61.0 15.3 1.4 10.0 10.0 11.8 0.5 18.5 11.1 1.1 13.3 3.3 14.3 1.5 1.0 2.4 0.80.3 TotalLong-tailedPacificNorway mammalsrat jumping weasel mouse (TOMA) 6.5 4.4 7.8 6.2 20.8 13.3 11.7 15.3 22.2 14.4 18.9 18.5 e 7.8 9.5 13.1 10.1 MiceInsectivoresTOMAInsectivores - deer mouse- vagrant + vagrant shrew shrew deer mouse 0.93.71.0 4.4 2.23.3 1.03.81.4 15.3 4.21.4 10.0 3.3 10.0 1.7 11.8 3.10.5 18.5 3.7 11.1 2.21.1 13.3 2.23.3 14.3 2.71.5 1.06.9 9.5 10.7 2.4 0.39.00.8 SpeciesVolesaintensive diversity firstsampling index 2 nights were used to calculate captures per 100 trap-nights. areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only the 0.951.9 1.272.2 0.741.4 0.731.4 0.56 0.41 0.570.5 0.45 0.681.1 0.803.3 0.641.5 0.37 0.482.4 0.280.8 dCapturedbintensiveCNt)ers in parentheses after secondsampling night. areas of similar habitat combined; seasons combined. equal trap-nights during first 2 nights. 1'CapturedeNO in non-standardized recordedcaptured, in but intensive was observed sampling and/or areas, identified but was byobserved sign in in this this habitat. habitat. traps wily. TABLE F. Wan index of abundance values (captures per 100 trap-nights) in sisal I mammal intensive sampling areas iliventori ed during fall 1974 and spring 1975 in segment 3 of the Oregon Columbia Washington River study area.a Is land IntensiveOregon Sampling Area Washington / Scasont Is land Oregon Oregon Washington Cottonwood S.A. 1 Cottonwood S.A. 9 CottonwoodS.A. 15 Cottonwood!F Willow Cottonwood/ Willow Cottonwood/ Willow F Cottonwood Willow/ Ash/ Cottonwood Willow! Ash! CottonwoodS.A. 11 Willow!Ash! DuskyVagrantSpecies shrew shrew or (roup (72) F2.8 (72) Sp (96) 3.2F (96)17.6 Sp (96) 5.6F (96) 3.0 S.A. 2 (78) Sp5.6 (96) 0.9FS.A. 10 (96) 7.8Sp S.A. 19 (96) 4.4 (96) 9.3F S.A. 3 (96) Sp3.2 S.A. 7 (96) F 8.7(96) F NorthernEasternShrew-moleBrush1 ownsend' rabbicottontail flying S :401 C dd d d d e C e e 1. 1 d C TotalLong-tailedTownsend'sDeer Mammals mouse volevole (TOMA) squirrel 20.818.0 13.912.5 1.4 42.238.0 1.1 29.812.2 7.62.0 14.810.8 1.1 31.921.4 5.0 24.122.0 1.1 31.717.8 2.83.3 43.037.6 0.9 11.3 2.0 18.715.6 5.94.8 49.138.3 2.0 VolesMiceInsectivoresInsectivoresflA - Deer Mouse + Vagrant Shrew Vagrant Shrew 18.0 2.8 12.5 1.4 38.0 1.13.2 12.217.6 2.1)5.62.0 10.8 1.13.01.1 21.4 5.65.0 22.0 1.10.9 17.8 7.86.1 37.6 4.40.9 2.09.3 15.6 3.2 4.8LI1.1 38.3 8.720 bNot"Intensive samplingfirst 2 nights areas were were usedsampled to calculateall intensive sampling areas were sampledcaptures2, 3 or during4 consecutiveper nights100 trap-nights. in the spring sampling fall 1974 and 5.0 3 or 1974;4 consecutive Sp= nights6.1 in 0.9 1975. spring 1975, but only tile 2.0 CNotdCapturedNuinher iii parentheses equal trap-nights duringcaptured, but was observed and/or in non-standardized traps only. identi fled first by sign in sampling2 nights. area. period; F= fall spring TABLE F. Continued. Oregon Reed Washington Reed Island Reed Intensive OregonWillow Sampling Area Washington Willow / WillowIsland casonb OregonShrub Wasliiiigton Shrub ShrubIsland Species or Group Canarygrass SA. 4 (96) Canarygrass(96) S.A.F 14 (96) Sj) CanarygrassS.A. 18 (96) F (96) F S.A. 5 (96) Sp S.A. 12 (96) F S.A. 16 (96) F (78) F S.A.Willow 6 (78) Sp (78) S.A.F 13 Willow (78) Sp S.A. 17 Willow (78) F Townsend'sShrew-moleDuskyVagrant shrew shrew iiiole 1.1 1.1 28.3 4.1 1.1 1.14.3 0.9 3.0 1.4 2.8 1.4 d 1.4 Townsend'sDeerNorthernEasternBrush mouse rat'bit flying cottontailvole squirrel lie8 e 7.25.2 e 2.2 20.5 2.0 ee 12.2 3.1 e 39.3 4.3 1.41.1 5.35.6 11.4 C 17.8 2.8 C TOMATotalInsectInsectivores[,ong-tai llaiiimals ivores led vole- Vagrant Shrew - Deer Mouse (P3MA) + Vagrant Shrew 1.1 18.9 1.1 28.340.7 7.2 4.16.32.2 23.7 1.12.0 20.7 5.44.31.1 44.4 0.94.3 3.03.0 3.91.4 13.6 2.85.3 12.8 1.4 20.6 2.8 1.41.4 alflteflsjveVolesMice samplingfirst 2 nights areas were were used sampled to calculate 2, 3 or 4 capturesconsecutive per 100 trap-nights. 17.8 7.25.2 nights in fall 2.2 20.5 2.0 1974 and 12.2 3.1 3 or 4 consecutive nights in 39.3spring 4.3 1.41.1 5.35.6 1975, 11.4 but only the17.8 2.8 dapte80cNumbersbNot ured all in intensive innon-standardized parentheses equal captured, but was observed and/or identified by sign in sampling sampling areas were sampled during the spring sampling period; F= trapstrap-nights on1y. during first 2 nights. area. fall 1974; Sp= spring 1975. TABLE G. 3Small of the mammal Columbia captures River per study 100 area.trap-nights and species diversity index values by trap station type in habitats inventoried in segment Ilabitat' / Trap Station Type Species or Group 1 Cottonwood 2 3(432)C X Cottonwood / Willow1 (462) 2 3 X Ash I Willow / Cottonwood (384) 1 2 3 X BrushTownsend'sShrew-moleI)uskyVagrant rabbitshrew shrow mole 1.3 2.9 14.5 6.2 d 1.7 2.8 8.3 4.3 e 4.2 3.3 0.88.3 0.35.3 NorthernGrayCaliforniaEastern squirrel cottontail flying ground squirrel squirrel df e dfe Townsend'sDeerLong-tailed mouse vole weaselvole 19.2 0.6 17.4 0.7 12.3 1.4 16.3 0.9 f 20.7 1.71.7 30.6 2.1 14.6 2.8 22.0 0.62.2 18.1 0.7 14.2 0.8 13.3 15.2 0.5 1O1AInsectivoresInsectiVorestotal - deer mammals mouse - vagrant+ vagrant shrew shrew (IOWA) 21.2 1.30.6 21.0 2.90.7 14.528.3 1.4 23.5 6.20.9 25.9 1.73.4 35.4 2.82.1 25.7 8.32.8 29.0 4.32.8 22.9 4.20.7 18.3 3.30.8 22.5 0.89.2 21.2 0.80.35.6 Species'kilosNicet4ice - deerdiversity mouse index 19.2 0.360.6 17.4 0.540.7 12.3 0.851.4 16.3 0.580.9 20.7 0.723.4 30.6 0.492.1 14.6 0.932.8 22.0 0.712.8 18.1 0.600.7 14.2 0.640.8 13.3 0.80 15.2 0.680.5 bintensiveajitensivefirst sampling 2 nights were used to calculate sampling areas of similar habitat combined; areas were sampled captures2, 3 or 4 consecutiveper 100 seasons combined.trap-nights. nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only the dCapturedCNLanbers in parentheses equal trap-nights during in non- standardized traps only. was observed and/or first 2 nights. in e0 captured, but recorded in intensive sampling areas, but identified was observed by sign in this habitat.this habitat. 0" TABLE C. Continued. llabitat' / Trap Station Type Species or Group Ileed1 Canarygrass (384)C 2 3 1 Willow (384) 2 3 1 Shrub Willow (390) 2 3 X BrushTownsend'sShrew-moleDuskyVâgant shrewsabbt shrew mole 3.5 5.8 16.7 8.7 e 2.8 0.81.7 2.5 0.32.3 ea 1.7 2.5 1.4 ed Towisend'sDeerNorthernCrayCalifornisEastern mouse squirrel cottontail flying groundvole squirrel squirrel 2.15.6 1.75.0 3.36.7 5.82.4 21.5 2.1 20.8 3.3 11.7 1.7 18.0 2.4 10.7 0.7 0.87.5 4.23.3 7.21.9 TOMATotalLong-tailed mammals weaselvole - deer mouse + vagrant shrew (TOMA) 11.1 3.52.1 12.5 1.7 26.716.7 3.3 16.8 2.4 26.4 2.1 26.7 4.22.5 15.8 1.7 23.0 2.7 11.3 0.7 10.0 0.81.7 10.0 4.2 10.4 1.41.9 MiceVolesIiisectivoresInsectivores - vagrant shrew - deer mouse 2.15.6 1.75.05.8 3.36.7 5.82.48.7 21.5 2.12.8 20.8 0.83.3 11.7 2.51.7 18.0 2.40.32.6 10.7 0.7 0.87.5 4.23.32.5 1.97.2 bintensivealriteiisiveSpecies diversity samplingfirst 2 indexnights areas were sampledused to calculate sampling areas of similar habitat combined; captures2, 3 or 4 1.02 per 100consecutive0.99 seasons trap-nights.0.90 nights in fall combined.0.97 1974 and 0.61 0.733 or 4 consecutive nights0.75 0.70 in spring 0.22 0.721975, but only 1.08 0.67 the KNOteNOdt.pturedCNumbers recorded in in non-standardized parentheses in intensive equal trap-nights captured, but was observed and/or sampling areas, but was traps only. identified by sign during first observed in this habitat. 2 nights. iii this habitat. 1ABLE H. Mean1974 index and of springabundance 1975 valuesin segment (captures 4 of theper Columbia 100 trap-nights) in River study area. s9ll mammal intensive sampling areas inventoried during fall OregonWillow Washington Willow OregonWillow Intensive Sampling AreaWashington Willow / ShrubOregon seusonh Douglas Oregon Fin Washington Species or Croup (42) F S.A. (42) Sp1 S.A. 15 (96) F (42) F S.A. (42) Sp2 S.A. 14 (78) F S.A.Willow 7 (96) F (66) F MapleS.A. (66) Sp3 I)ouglas Fir!(60) S.A.F 11Maple (60) Sp CoastShrew-moleTrowhiidge'sPacificVagrant mole watershrew shrew shrew d 2.8 e 1.92.8 2.8 e 1.1 3.3 1.9 1.4 NorthernDouglas'CaliforniaYellow-1,elliedTownsend'sNuttall's cottontailflying groundchipmunk marmot sqili squirrel rrel luIrrel 1.9 d 4.2 df 1.9 d d MontancNorthernllushy-taiDeerWe tern volepocket ha led rvest woodrat gopher lijouse IUOUSO e 4.34.4 17.6 2.8 d 3.1 21.3 17.2 13.4 1.4 7.4 TOMATotalTownsend'sInsectivoresLong-tailed tianimals vole vole fleer Mouse + Vagrant Shrew (TOMA) 5.5 14.817.610.2 7.4 4.38.7 12.933.3 4.69.2 26.929.621.3 5.6 1.14.3 25.5 4.2 22.2 5.13.3 16.7 1.93.3 8.81.4 VolesMiceInsectivores - I)cer Mouse Vagrant Shrew 5.5 10.2 4.6 4.34.4 17.6 9.21.9 21.3 5.62.8 3.1 21.3 17.2 3.3 13.4 1.9 7.41.4 bNot theIntelisive first 2 nights sampling were areas used were to sampledcalculateall captures intensive Ier sampling areas were sampled2, 3 or 4 during consecutive nights in fall the spring sampling 100period; trap-nights. 1974 and 3 or 4 consecutiveF= fall 1974; nights in spring 1975, but only Sp= spring 1975. eNOdNotLNumbersCapturcd in parentheses in non- equalstandardized trap-nights traps oiily.capturedcaptured, but until was third observed night. and/or identified by sign during first 2 nights. in sampling area. TABLE H. Continued. intensive Sampling Area / Season' PonderosaOregon Oak/ WashingtonPonderosa Oak! Oregon Oak Washington Oak GrasslandOregon WashingtonGrassland Rip-RapOregon Rock Washington lip-Uap Rock Species or Group (96) F S.A. 4 Pine (96) Sp S.A. 13 Pine(78) F (96) F S.A. 5 (96) Sp S.A. 10 (42) F (42) F S.A. 6 (42) Sp (42) S.A.F 12 (42) Sp (96) F S.A. 8 (96) Sp (96) FS.A. 16 (96) Sp Shrew-moleTroebridge'sPacificVagrant watershrew shrewshrew 1.4 1.1 d Yellow-belliedTownsend'NuttallCoast mole 's acottontail chipmunk marmot d d d d NorthernCalLfornlaWesternNorthernDouglas harvest groundpocket squtrrelmousegopher squirrel lying squirrel f 1.9 f d d 4 Deer mouse 4.3 9.8 6.1 22.2 12 8 7.41.9 8.3 38.0 46.3 14.8 20.5 30.7 ' 39.3 Townsend'sMontanoLong-tailedBushy-tailed vole vole vole woodrat 0 2.0 e 1.9 4.6 0.9 0.9 TOMATotalInsectLvoresInsectivores - MammalsDeer Mouse - Vagrant+ Vagrant Shrew Shrew (TOMA) 4.3 9.8 1.47.51.4 24.2 2.0 13.9 1.1 1.99.2 10.2 1.9 39.8 1.9 50.9 4.6 15.8 0.9 21.5 0.9 30 7 39.3 °lntensiveVolesMice - Deer sampling Mouse 4.3 9.8 6.1 22.2 12.8 9.21.9 8.3 38.0 1.9 46.3 4.6 14.8 20.5 3(1.7 39.3 CNIIMbersbNOt infirst 2 iiights were used to calculate capturesall inl.cnsive per 100 samplingtrap-nights. areas were sampled during the spring sampling period;parentheses F' fall equal 1974; trap-nights Sp during first 2 nights. areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only the spring 1975. CNotdNot Captured in non-standardized traps only. capturedcaptured, untilbut was third observed night. and/'or identi fled by sign in sampling area. TABLE 1. Small mammal captures per 100 trap-nights and species diversity index values by trap station type in habitats inventoried in segment 4 of the Columbia River study area.a Willow (342)c Habitat Shrub Willow (96) / Trap Station Type IJouglas Fir I Maple (252) PacificVagrantSpecies waterorshrew Group shrew 1 1.0 2 1.0 3 O7 X 1 2 3.3 3 1.1 X 1 2 3 X Townsend'sSnowshoeNuttaiPsCoastShrew-moleTrowbridge's mole harecottontail chipmunk shrew 0.7 1.0 1.0 0.20.60.9 f 2.1 1.2 1.4 1.6 d Douglas'WesternCaliforniaYellow-bellied gray squirrel ground squirrel marmot squirrel d gd MontaneIieerWesternNorthernBushy-tailed harvestvole pocket flying woodrat mouse gophersquirrel ,liouse 0.71.4 2.08.8 1.0 1.23.7 2.8 3.3 3.3 3.1 17.7 1.0 20.2 8.3 15.4 0.3 T0t'IATotalLong-tailedTownsend's mammals - deer vole mousevole (TOMA) + vagrant shrew 8.09.43.61.4 18.6 8.83.92.0 10.8 8.83.92.01.0 12.9 8.53.81.8 2.8 3.3 6.7 4.3 22.9 5.2 22.6 2.4 11.1 2.8 18.9 3.5 MiceIiisectiijisectjvores vores - deer mouse - vagrant shrew 1.4 8.82.01.0 1.02.02.9 3.71.52.1 2.8 3.3 3.33.3 3.11.1 17.7 2.1 20.2 1.2 8.31.4 15.4 1.6 binteiisiveaInte,siveSpeciesVies diversity samplingfirst 2 indexnights were used to calculate captures ier 100 trap-nights. sampling areas of similar habitat combined; seasons combined. areas were sampled 2, 35.8 or1.71 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in7.8 spring1.48 1975, but only the 1.786.9 1.666.8 0.00 0.00 0.70 0.23 0.77 0.41 0.74 0.64 tNotdNotCNumbers recordedcapuredNot in capturedparentheses in intensive in non-standardized until equal sampling third trap-nights night. traps only.captured, but was observed and/or identified by sign in this habitat. areas, but was observed in this habitat. during first 2 nights. Continued. TABLE I. Oak / Ponderosa Pine (270)C Oak (234) 1labitat / Trap Station Type Grassland (168) Rock Rip-Rap (384) VagrantSpecies shrewor Group 1 2 3 X 1 2 1.4 3 0.5 X 1 Z 3 dX 1 2 3 X Nuttall'sCoastShrew-moleTrowbridgc'sPacific mole water cottontail shrewshrew 1.2 0.4 d CaliforniaYellow-belliedTownsend'sSnowshoe hare groundchipmunk marmot squirrel g gd d NorthernDouglas'Western gray squirrelflyingpocket squirrel squirrelgopher 1.4 0.5 MontaneBushy-tailedDeerWestern mouse voleJiarvst woodrat mouse 4.9 11.9 2.4 6.4 16.7 1.1 16.7 1.4 9.7 14.4 0.8 16.7 2.81.4 37.5 20.8 2.1 25.0 0.51.6 25.7 1.4 35.0 18.3 26.3 TOMATotalLong-tailedTownsend's - mammalsdeer volemousevole + vagrant shrew (TOMA) 4.9 13.1 1.2 2.4 0.46.8 e 17.8 1.1 18.1 1.4 11.1 15.7 0.8 e 22.2 5.6 37.5 22.9 2.1 27.5 2.6 27.1 1,4 35.0 18.3 26.8 0.5 MiceInsectivores - deer mOuse - vagrant shrew 4.9 11.9 1.2 2.4 6.40.4 16.7 16.7 9.71.4 14.4 0.5 18.1 1.4 37.5 20.8 25.5 0.5 25.7 35.0 18.3 26.3 aintensiveSpeciesVoles diversityfirst 2 indexnights were used to calculate captures per 100 trap-nights. sampling areas were sampled 2, 3 or 4 consecutive nights in fall 0.00 0.31 0.00 0.10 0.23 0.27 19740.38 and 3 or 4 consecutive nights in spring 1975, but only 0.29the 0.822.8 0.00 0.312.1 0.381.6 0.20 0.00 0.00 0.07 cNumberSbinteiisive in parentheses equal trap-nights (luring captured, but was observed and/or identified by sign in this habitat.sampling areas of similar habitat combined; seasons combined. first 2 nights. eNO Captured in non-standardized traps only. recordedcaptured inuntil intensive third night.sampling areas, but was observed in thi habitat. TABLE J. andMean spring index 1975 of abundance in segment values 5 of the (captures Columbia per River100 trap-nights) study area. A small mammal intensive sampling areas inventoried (hiring fa1l 1974 Oregon Washington Oregon WashingtonIntensive Sampling Area / Season Oregon Oregon Oregon Rock Washington Rock Species or Group Rabbitbrush S.A. 1 (96) F c Rabbitbrush(66) S.A. (66) Sp8 GrasslandRockcliff/ S.A. 2 (78) F GrasslandRockcliff/(42) F S.A. 9 (42) Sp (60) F S.A.WillowShrub 3 (42) Sp (78) F S.A.Willow (60) Sp4 (96) F S.A.Rip-Rap 5 (96) Sp (96) F S.A.Rip-Rap 7 (96) Sp CaliforniaYellow-belliedBlack-tailedNutta1l ground jack matmot rabbitsquirrel cottontail ed d d ed d d d d d d Bushy-tailedDeerWesternGreatNorthern mouse Basin harvest pocket pocket woodrat mousegopher mouse 24.7 38.9 5.6 f 23.3 15.7 1.9 a 8.32.8 31.5 25.0 18.6 33.3 26.1 i. ii 29.1 ii 41.1 25.6 MiceTOMATotal Mamimmais - Deer Mouse ('I'OMA) 24.7 38.9 5.65.6 23.3 17.6 1.9 11.1iLl 2.8 31.5 25.025.0 f 18.6 33.3 27.2 1.1 29.1 41.1 25.629.t 4.1 MicebNotUInteIIslVefirst 2 nights were used to calculate CaptureSall intensive per 100 samplingtrap-nights.Deer areas Mouse were sanipled during the spring samplingsampling period;areas were F sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 1.9 2.8 or 4 consecutive nights in spring 1975, but only the 1.1 CCapttlrcddNotCNurnbertNot captured in captured, but was observed and/or identified by sign inin samplingnon-s tandaparentheses rdi zed traps equal only. trap-ni ghts duringwit ii third first night.2 nights. area. fall 1974; Sp= spring 1975. TABLE K. stationSmall mammal type in habitatscaptures inventoried per 100 trap-nights in segment and 5species of the diversityColumbia index River values study by area.a trap (228)Cllabitat' / Trap Station Type Nuttall'sSpecies or cottontailGroup 1 Rabbitbrush 2 3 X Rockcllff / Grassland1 (162) 2 3 X GreatNorthernCaliforniaYellow-belliedBlack-tailed Basin pocket ground pocket marmot jackgopher mousesquirrel rabbit fgd 1.5 2.1 1.2 fd TOMATotalBushy-tailedWestern mammals - deerharvest ecrmouse woodrat mouse mouse (TOMA) 25.0 28.228.2 16.7 23.3 10.612.1 1.5 25.022.9 2.1 18.8 18.617.4 1.2 (1 aintensiveSieciesMice diversity sampling100secutive trap-nights. index nights in spring 1975, but only the first 2 nightsdeer were mouse used to calculate captures per areas were sampled 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 con- 25.0 0.00 28.2 0.00 16.7 0.00 23.3 0.00 12.1 0.371.5 25.0 0.292.1 18.8 0.00 18.6 0.221.2 dcNufllbersbintensive in parentheses sampling areas of similar habitat combined; seasons combined. equal trap-nights during first 2 nights. . . e CapturedNot recordedcaptured, in non-standardized inbut intensive was observed sampling traps and/or only. areas, capturedidentified but was until byobserved sign third in night. inthis this habitat. habitat...... N) TABLE K. Continued. llabitat' / Trap Station Type Species or Group 1 Shrub Willow 2 3 (102)C dX 1 Willow (138) 2 3 dX 1 flock Rip-Rap (384) 2 3 eX CaliforniaYellowhdUjedNuttall'sBlack-tailed cottontail ground marmot jack squirrel rabbit f (I Bushy-tailedDeerWesternGreatNorthern mouse Basin harvest pocket pocket woodrat mousegopher mouse 33.3 40.0 16.7 300 5 29.6 28.6 16.7 25.0 26.4 1.4 43.3 0.81.7 21.7 30.5 0.31.0 SpeciesMiceTOMATotal utaimnals- deer diversity mouse index - deer mouse (TOMA) 33.3 0.00 40.040.0 0.00 16.7 0.00 30.030.0 0.00 ' 29.6 0.00 28.6 0.00 16.7 0.00 25.0 0.00 26.427.8 0.201.4 44.245.8 0.250.82.5 21.7 0.00 30.831.8 (hiS0.31.3 CNumbersbintensivealmitensive infirst parentheses 2 nights wereequal usedtrap-nights to calculate captures per 100 trap-nights. sampling areas wereof similar sampled habitat 2, 3 or 4 consecutive nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only time during first 2 nights. onmbined; seasons combined. eNOdNot Captured iii non-standardized traps only.capturedrecordedcaptured, in untilbut intensive was third observed night. sampling and/or areas, identified but was byobserved sign in in this this habitat. habtiat. 'IABLF 1.. Meanand index spring of 1975abundance in segment values 6 (captures per of the Columbia River100 studytrap-nights) area. in small mammal intensive sampling areas inventoried during fall 1974 Oregon Rock TalusOregon Washington Talus Rockcliff/IntensiveOregon Sampling Area WashingtonIloekcliff/ Sagebrush/ Oregonseasoub SagebrushWashington Bitterbrush Oregon WashingtonBitterbrush Species or Group (96) S.A. 11 Rip-Rap (96) Sp (96) F S.A. (96) Sp1 S.A. 16 (96) F Grassland(96) F S.A. 2 (96) Sp Grassland S.A. 17 (72) F (96) F S.A. 3 (96) Sp S.A. 18 (60) F (96) F S.A. (96) Sp4 (96) FS.A. (96)12 Sp Black-tailedNut tall's cottontail jack rabbit d d d d d d dci d d I d CaliforniaTownsend'sYellow-bellied groundchipmunk marmot squirrel d d d ed d d ed d e Ord'sWesternGreatNorthern kangaroo Basin harvest pocket pocketrat moosegopher mouse 1.4 8.81.9 3.01.1 4.82.21.1 6.1 2.06.1 MontancNorthernNorwayBushy-tailedDeer mousevole grasshopperrat wocidrat mouse 28.3 d 38.3 d 31.5 0.9 19.4 2.0 46.9 e 46.5 0.9 25.9 0.9 11.1 d 31.5 39.6 3.7 2.2 6.1 2.0 3.31.1 MiceTOMATotalHouse Mammalsmouse Deer Mouse (TOMA) 28.3 38.3 31.532.4 0.9 19.421.5 2.0 46.9 47.446.5 0.9 25.926.9 0.9 12.5 1.4 31.5 39.6 14.410.7 6.34.1 14.3 8.1 8.26.1 12.6 9.3 a11105VolesMice ivc Deer Mouse sampling areas were sampled 2, 3 or 4 consecutive 1.4 10.7 4.1 8.1 6.1 9.3 1NumberbNot in parenthesesfirst 2 nights equal were trap-nights used to calculate during firstall intensive sampling areas were sampledcaptures duringper 100 2the nights. spring sampling period;trap-nights. F= fall 1974; Sp= spring 1975. nights in fall 1974 and 3 or 4 consecutive nights in spring 1975, but only the £CaptureddNot Not captured until third night. captured, but was observed and/or in non-standardized traps only. identified by sign in sampling area. 'l'ABLIi L. Cont inued. Intensive Sampling Area / easonb Rabbithrush Oregon BabbitbrushWashington GrasslandOregon WashingtonGrassland Cottonwood! OregonWillow Cottonwood!Washington Willow Oregon Marsh 8 Washington Marsh 15 OregonS.A.UussianOlive 9 - F S.A. 5 Sp FS.A. 13 Sp F S.A. 6 Sp FS.A. 14 Sp P S.A. 7 Sp S.A. 19 F F S.A. (96) Sp (78) S.A.F (78) Sp (78) P (78) Sp NuttallSpecies ors cottontailGroup . (96) d (96) cid (96) d (96) dd (96) dci (96) d (96) d (96) d (60) d (60) d (78) (96) d d d d e d Townsend'sYellow-belliedBlack-tailed ground jack mansot rabbit squirrel i Ord'sGreatNorthernCalWestern Basinkangaroo pocket harvest pocket ratgopher mouse mouse fornia ground squirrel d 631.1 LI1.1 2.23.3 d 0.9 3.2 1.1 e 12.0 d d 2.2 d 6.3 e 8.3 e d 3.6 MontaneBushy-NorthernDeer mouse tal volegrasshopper led wuodrat mouse 6.3 4.4 1.1 1.1 5.1 LI 2.2 1.1 ci 2.2 2.8 (I TotalhouseNorway lOMAhlammals mouse rat - Deer Mouse (TOMA) 6.3 11.9 7.4 2.23.3 5.6 0.9 3.2 1.12.2 12.017.1 1.1 4.5 9.62.28.5 11.9 9.71.4 14.812.0 7.5393.67.5 11.711.7 3.6447.2 MiceU1S,0Voles - Doer Mouse sampling areas were sampled 6.3 11.9 7.4 2.23.3 4 consecutive5.6 nights 0.9 3.2 1.12.21974 and 3 or 4 consecutive nights in 12.017.1 i.i 2.2 8.59.6 spring 9.71975, 12.0 but only the 3.6 7.2 first 2 nights were used to calculate i captures2, 3 or per 100 trap-nights. in fall liNotdNotCNumherstNot all captured, captoredCapt in parenthesesured but until wasin non-s thirdobserved equal tandardi night. trap-nights and/or zed traps only. nteits lye sampling areas were identifiedsampled during during first by sign the spring sampl2 nights. iii sampl lug area.lug period; F= fall 1974; Sp= spring 1975. TABLE M. segmentSmall mammal 6 of thecaptures Columbia per River100 trap-nights study area.a and species diversity index values by trap station type in habitats inventoried in Rock Rip-Rap (192)C Habitat" / Trap Station Type Talus (288) Rockcliff / Grassland (264) Species or Group 1 2 3 dX 1 2 3 d1 1 2 3 I Townsend'sYellow-belliedWhite-tailedNuttall'sBlack-tailed cottontailground jack marmotjack squirrelrabbit rabbit d d d WesternOrd'GreatNorthernCalifornia a Basinkangai'oo harvest pocket groundpocket ratmousegopher squirrelmouse d 1.2 0.4 e NorwayMontaneBushy-tailedNorthernDoer mouse rat vole grasshopper woodrat mouse 33.3 43.3 23.3 33.3 d 33.3 1.9 37.8 1.1 26.7 32.6 1.0 32.3 2.1 39.3 16.7 29.4 0.7 1T4ATotalhouse -mammals mousedeer mouse (TOMA) 33.3 43,3 23.3 33.3 35.2 1 .9 38.9 1. 1 26.7 33.6 1 .0 34.4 2. 1 39.3 17.9 1.2 30.5 1 . MiceaI,,tensivoSpecies - deer diversity mouse sampling index 33.3 0.00 43,3 0.00 23.3 0.00 33.3 0.00 33.3 0.21 37.8 0.13 26.7 0.00 32.6 0.11 32.3 0.23 39.3 0.00 17.9 0.251.2 29.8 0.160.4 cNUWbCIShltitensive infirst 2 nights were used to sampling patenthesesareas of equal areas were sampled 2, 3 or 4 consecutive nights in fall similarcalculate habitat capturestrap-nights combined; per 100during seasons trap-nights. first combined. 2 nights. 1974 and 3 or 4 consecutive nights in spring 1975, but only the °CapturoddNOt N0t in recordednon-standardized jn intensive sampling captured, but was observed traps only. and/or identified by sign in this habitat.areas, but was observed in this habitat. 8Not captured until third night. -'0" TABLE M. Cc.ntinucd. I!abitat / Trap Station Type Species or Group 1 Sagebrush (252)C 2 3 X 1 Rabbitbrush (384) 2 3 X 1 Bitterbrush (384) 2 3 X 1 Grassland (384) 2 3 X Nuttall'sBlack-tailedWhite-tailed cottontail jack rabbit d df d d NorthernCaliforniaTownsend'sYellow-bellied pocket ground marmot gopher squirrel ed f Ord'sGreatDeerWestern kangarooBasin mOuse harvest pocket rat mousemouse 25.0 1.0 38.5 1.3 20.5 5.1 28.0 0.42.0 1.4 6.73.30.8 0.85.0 3.01.4 4.22.80.74.2 4.20.83.3 3.30.84.21.7 3.40.82.03.9 0.7 0.82.5 0.30.21.1 houseNorwayMontaneNorthernBushy-tailed mouserat vole grasshopper woodrat mouse g 0.8 0.3 MiceTONA fetal- deerdecr rnan',j,als mouse (TOMA) 26.0 1.01.0 39.7 1.3 25.625.6 5.1 30.4 2.5 1.42.8 10.8 4.2 6.75.8 6.83.8 11.8 9.0 8.34.2 10.8 7.5 10.3 6.9 1.41.4 3.32.5 1.61.3 Species"Intensive diversity firstsampling index 2 nights areas were used to were sampled 2, 3 or 4 consecutIvecalculate captures per 100 trap-nights. 0.16 0.14 0.50 0.27 nights 0.69 in fall 0.854.2 19740.735.8 and 3 0.763.8 or 4 consecutive 1.249.0 0.944.2 nights7.51.41 in 1.206.9 spring 1975, but 0.691.4 0.00 only 0.552.5 the 0.411.3 dNot'Numbersbintensive in parentheses captured, but was observed sampling areas of equal similar habitattrap-nights combined; during seasons firstand/or 2combined. nights.identified by sign in this habitat. eCd in non-standardized capturedrecorded untilin intensive third night. sampling traps only. areas, but was observed in this habitat. TABLE H. Continued. Cottonwood / Willow (198)C Ilabitat Russian Olive (156) / Trap Station Type Marsh (312) White-tailedNuttail'sSpecies or cottontailGroup jack rabbit 1 2 3 dX 1 2 3 eX 1 2 3 dX GreatNorthernCaliforniaYellow-belliedBlack-tailedlowasend's Basin pocket ground pocket jackground marmot gopher mouserabbitsquirrel squirrel e c NorthernBushy-tai[edDeerWesternOrd's mouse kangaroo grasshopper harvest woodrat mouserat mouse 1.32.6 8.3 3.3 3.61.5 3.3 2.2 1.8 d 1.7 2.16.3 6.3 4.81.3 houseNorwayMontane mouse rat vole - 1.3 0.4 6.78.3 2.14.2 2.1 3.64.2 1.7 3.12.1 3.1 2.60.7 d MiceTOMATotal mammals - deer mOusemouse (fOMA) 2.63.85.1 8.3 3.3 3.65.14.05.6 10.018.3 2.16.3 4.2 5.49.6 3.35.0 11.513.5 9.4 9.4 8.68.19.37.4 bimitensiveaintejisiveSpecies diversity samplingthe first index 2 nights were used sampling areas of areas were sampled 2, 3 or 4 consecutive similar habitatto calculate combined; captures seasons per 100 1.04 0.00 0.00 trap-nights.nights0.35 in fall combined. 1.041974 and 3 or 0.64 40.69 consecutive 0.79 nights in spring 1975, but 1.10 1.27 0.63 only 1.00 KNOtecaptureddNotCNumnbers recorded in in non-standardized parentheses in capturedcaptured, until but thirdwas observed night. intensive sampling equal trapstrap-nights only. during firstand/or 2 nights.identified by s:ign in areas, but was observed in this habitat.this habitat.