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Limiting Factors

Fish

The primary limiting factors to salmonid abundance and distribution were defined by the Columbia Basin Fish and Wildlife Authority (Draft Annual Implementation Work plan 2000) as:


  • Inter-related water quantity and quality problems (e.g., low flows/high temps. & pollutants) result in poor survival during juvenile rearing and migration in the lower Umatilla River.

  • Low flows and diversion barriers restrict adult migration

  • Riparian degradation and lack of pools reduces adult holding and juvenile rearing survival in the upper reaches of the Umatilla subbasin

  • Water quantity, quality, and sediment problems limit salmonid spawning and rearing

  • Mainstem passage problems and other habitat alterations as a result of Columbia River mainstem dams

Key species, such as bull trout, steelhead, spring and fall chinook, and coho have a narrow range of biological requirements and can persist only in areas of suitable habitat. In the Umatilla, these areas and conditions are often inaccessible to migrating and resident species. Limits to fisheries production outside the subbasin include incidental harvest during migration and poor ocean survival. Conditions in the Columbia River also cause significant mortality for both outmigrating juveniles and returning adults. This in-river mortality results from hydroelectric dams, low velocity pools formed by the dams, predation from piscivores, and warm water temperatures. This combination of out-of-basin and in-basin factors have reduced native anadromous fish populations within the subbasin to precipitously low levels. These factors are summarized in Table 42.

Table 43 identifies known and suspected limiting factors in the Umatilla subbasin at stream reach scale. Although not comprehensive, the list identifies primary factors known to limit key species production in various portions of the subbasin. The table is stratified into three general reaches, which correspond to similar land uses and channel type. Within each broad reach, a number of stream segments are evaluated. For each reach, key limiting factors are presented for the five salmonid species occurring in the subbasin. Each species is evaluated at one of three life history phases: migration (M), spawning (S) and rearing (R). An “X” denotes the presence of a limiting factor.

Life history limitations are highly variable depending on the reach and species considered. This is due in part to differences in environmental factors between reaches, and the specific biological requirements inherent to the respective species. For example, in the lower portion of the basin, from the mouth to RM50, the primary land use is irrigated agriculture. Therefore, flow limitations and passage impediments are common as a result of the numerous irrigation diversions. The species most affected in this area are fall chinook, which commonly use the lower reach for rearing; however, coho, spring chinook and steelhead use this section of river for migration purposes during peak irrigation periods.

Table 42. General Characterization of Non-Habitat and Out-of-Subbasin Factors Limiting Salmonid and Lamprey Production in the Umatilla Basin


Limiting Factor


Description

Out-of-basin mortality (low smolt-to-adult return rates)

Ranks as high limiting factor. Anadromous fish must migrate past three mainstem Columbia River dams twice during their downstream and upstream migration. Columbia River passage, water quality, and estuary conditions are the major concerns.


Current low population size

Ranks as high limiting factor. Current spawning levels of fall chinook, coho, and steelhead are well below target objectives. This does not provide adequate parental base from which to build. Even if population replacement could be maintained, levels would still be far below natural production capabilities and numeric objectives. Spring chinook have, in some years, achieved target spawning escapement levels but total return and harvest objectives have not been met. Maintenance of hatchery supplementation (and addressing habitat factors) is recommended to increase and sustain parental population bases.


Low instream nutrient contribution from salmon and lamprey carcasses.

Ranks as a moderate limiting factor. Extirpated spring chinook runs have eliminated a major natural nutrient input source, which has reduced productivity in the aquatic ecosystem. Returning natural nutrient input will require successful reintroduction of natural spawning salmon and lamprey populations.



Lack of law enforcement for compliance with environmental protective requirements

Ranks as a moderate limiting factor. Environmental protective regulations such as Section 404 Fill and Removal Permits, Water Quality Standards, Local Land Use Planning Requirements and ESA Take Prohibitions are sometimes not followed and/or enforced resulting in negative impacts to fish and wildlife impacts.


Table 43. Key factors limiting fish production (species and life history) by stream segments in the Umatilla subbasin



Location

Key Limiting Factors 1/

STS

Impacts

CHS

Impacts

CHF

Impacts

COHO

Impacts

BT

Impacts

M

S

R

M

S


R

M

S

R

M

S

R

M

S

R

Umatilla Headwaters to Meacham Creek














































North Fork

None- Key stronghold area

All species and life histories benefited

South Fork

TP, CH

--

--

X

--

X

X

--

--


--

--

--

--

--

X

X

Mainstem Umatilla – Forks to Meacham Cr.

IHD, CH

--

--

X

--

--

X

--

--

--

--

--

--

--

--

X

Ryan & Bear Creeks

FL

--

--

X

--

--

X

--

--

--

--

--

--

--

--

X

Meacham Creek

FL, TP, CH, IHD, RIP


--

--

X

X

X

X

--

--

--

--

--

X

--

X

X

Mouth of Meacham to Mouth of McKay Creek














































Mainstem Umatilla – Meacham Cr. to Cayuse

FL, TP, CH, IHD, RIP

--

--

X

--

X

X

--

--

--

--

--

X


--

--

X

Mainstem Umatilla – Cayuse to McKay Cr.

FL, TP, CH, IHD, RIP

--

--

X

--

X

X

--

--

X

--

--

X

--

--

--

Squaw and Buckaroo Creeks

FL, TP, IHD, RIP

--

--

X

--

--

X

--

--

--

--

--

X

--

--

X

Coonskin, Moonshine, Cottonwood, Mission

FL, TP, PAS, CH, IHD,SED

--

--

X


--

--

X

--

--

--

--

--

X

--

--

--

Wildhorse Creek

FL, TP, PAS, CH, IHD, SED, RIP

--

X

X

--

--

--

--

--

--

--

--

X

--

--

--

Tutuilla Creek

FL, TP, CH, IHD, SED, RIP

--

--

X

--

--

--

--

--

--

--

--

X

--


--

--

McKay Creek

FL, PAS, CH, IHD, RIP

--

--

X

X

X

X

X

X

X

X

X

X

--

--

X

Mouth of McKay to Umatilla River Mouth














































Mainstem Umatilla – McKay Cr. to Westland

FL, TP, CH, IHD, SED, RIP, PASS2/

--

--

X

--

--

--


--

X

X

--

X

X

--

--

--

Mainstem Umatilla – Westland to Mouth

FL, TP, WQ, PAS, CH, IHD, SED, RIP

X

--

--

X

--

--

X

X

X

X

X

X

--

--

--

Birch Creek

FL, TP, PAS, CH, IHD, SED, RIP

--

--

X

--

--

--

--

--

--

--

--

X

--

--

--

Butter Creek


FL, TP, PAS, CH, IHD, SED, RIP

X

X

X

--

--

--

--

--

--

--

--

--

--

--

--

1/ Key Limiting Factors: FL=flow : TP=water temperature ; WQ=water quality (chemical) ; PAS=passage ; CH=channel conditions ; IHD=instream habitat diversity ; SED=sedimentation ; RIP=riparian ; X=impact to specified life history stage

2/ With the exception of adult migration at Feed Canal Dam, fish passage conditions for all species are thought to be adequate following completion of Umatilla Basin Flow Project and Ladder/Screen projects.



Wildlife

Conversion and Fragmentation of Habitat

Loss of habitat is the primary factor limiting wildlife populations in the subbasin. Late seral ponderosa pine dominated forests in the region have declined by 75-80% (Henjum et al. 1994). Wetland losses of up to 90% are documented along sections of the Umatilla River corridor (Kagan et al. 2000). Approximately 65% of the historic grass and shrublands of the Umatilla/Willow subbasin has been converted to agricultural cropland (Kagan et al. 2000). This large-scale habitat loss limits the potential for the Umatilla/Willow subbasin to support the wildlife species dependent on these habitats.

Fragmentation of remnant habitats further reduces their suitability for wildlife and increases their susceptibility to noxious weed invasion and other outside influences. Accelerating fragmentation resulting from disturbances, such as the expansion of crop cultivation or range fire, reduces patch size/home range ratios, and increases the access of predators and parasites to remaining habitat as edge increases relative to core habitat area.

Fragmentation of shrub steppe has altered the dynamics of dispersal and immigration necessary for maintenance of some populations at a regional scale (Altman and Holmes 2000a, 2000b). In a recent analysis of neotropical migratory birds within the Interior Columbia basin, most species identified as a high concern to management were dependent on shrub steppe habitat (Saab and Rich 1997).

Habitat fragmentation and high edge densities are conducive to significantly increased parasitism of the nests of other bird species by cowbirds. Cowbirds forage in agricultural areas, and near livestock. Bird species nesting in habitat patches near these areas experience increased exposure to nest parasitism, and reduced reproductive success as a result. Nest parasitism by cowbirds has been documented for over 220 bird species, and at least 144 species have successfully fledged cowbird young. Source habitats for cowbirds have increased by ≥ 60% over historic conditions in all but two of the 54 fifth field HUCs in the Umatilla/Willow subbasin (Wisdom et al. 2000).

Table 44 and Table 45 illustrate some key habitat components for certain focal species and their respective limiting factors in the Umatilla/Willow subbasin for shrub steppe and riparian habitats. The loss of healthy riparian corridors is particularly problematic to the wildlife species of the subbasin as it limits their ability to disperse when habitat conditions change.

Table 44. Habitat relationships of focal species in riparian habitats of the Columbia plateau Landbird Conservation Planning Region (from Altman and Holmes 2000a, 2000b)



Conservation Focus

Focal Species

Key Habitat Relationships

Vegetative Composition a

Vegetation Structure b


Landscape/Patch Size

Special Considerations

large snags

Lewis’s woodpecker

cottonwood

>2 snags/ha >16 in dbh; >2 trees/ha >21 dbh; canopy cover 10-40%; shrub cover 30-80%




dependent on insect food supply; competition from starlings detrimental

large canopy trees

Bullock’s oriole

cottonwood

canopy tree height >35 ft; canopy closure 30-60%; recruitment trees >10% cover




not area-sensitive; not landscape-sensitive; positive response to edge

subcanopy foliage

yellow

warbler


willow, cottonwood,

>70% cover in shrub and subcanopy with subcanopy >40% of that; >70% cover native species





highly vulnerable to cowbird parasitism; grazing reduces understory structure

dense shrub layer

yellow-breasted chat

willow, snowberry, wild rose

shrub layer 1-4 m tall; 30-80% shrub cover; scattered herbaceous openings; tree cover <20%




vulnerable to cowbird parasitism; grazing reduces understory structure

large, structurally diverse patches

yellow-billed cuckoo

cottonwood, willow

3 or more layers with >20% cover in each layer; canopy closure >50%; patches wider than 100 m and >40 ha

>40 ha

close to extirpated; area-sensitive; susceptible to human disturbance

shrub density

willow flycatcher

willow

shrub patches >10 m sq; shrub cover 40-80%; shrub height >1 m; tree cover <30%

>8 ha

highly vulnerable to cowbird parasitism; grazing reduces understory structure

shrub-herbaceous interspersion

lazuli bunting

willow, snowberry, red-osier dogwood

interspersion shrub and herbaceous where neither >70%





highly vulnerable to cowbird parasitism

aPreferred species.

bVegetative structure is a condensed version of the habitat objectives for each species. Refer to the text for more detailed description of habitat objectives.

Table 45. Habitat relationships of focal species in shrub steppe habitats of the Columbia plateau Landbird Conservation Planning Region (from Altman and Holmes 2000a, 2000b)




Conservation Focus

Focal

Species

Key Habitat Relationships

Vegetative Composition a

Vegetation Structure b


Landscape Patch Size

Special Considerations

native bunchgrass cover

grasshopper sparrow

native bunchgrasses

bunchgrass cover >15% and >60% total grass cover; bunchgrass >25 cm tall; shrub cover <10%;

>40 ha

(100 ac)

larger tracts better; exotic grass detrimental; vulnerable in agricultural habitats from mowing, spraying, etc.


interspersion tall shrubs and openings

loggerhead shrike

sagebrush, bitterbrush

patches shrubs >1 m tall; <15% tall shrub cover; shrub height >1 m; herb cover <20%; open ground >30%




prey base may be affected by pesticides; need low ground cover; invasion of exotic grasses detrimental

burrows

Burrowing

owl





open ground cover >40%; native grass cover <40% and <40 cm tall




dependent upon burrow providers (e.g., ground squirrels, badgers); sensitive to nest disturbances; 200 m buffer zone around nest burrow

deciduous trees and shrubs

sharp-tailed grouse




canopy cover 15-35% >15 cm above ground; forb cover >10%; non-native herbaceous cover <5%







large areas; diverse herbaceous understory

Sage grouse

big sagebrush

sagebrush cover 10-30%; forb cover >10%; bunchgrass cover >10%; open ground cover >10%; non-native herb cover <10%





area-sensitive

large, contiguous patches sagebrush

Sage sparrow

big sagebrush

sagebrush cover 10-25%; sagebrush height >50 cm; herb cover >10%; open ground >10%

>1,000 ha

(2,500 ac)



area-sensitive, needs large blocks; patchy sage preferred over contiguous dense sage; vulnerable to cowbirds

sagebrush cover

Brewer’s sparrow

big sagebrush

sagebrush cover 10-30%; sagebrush height >60cm; herb cover >10%; open ground >20%; non-native herb cover <10%




not area-sensitive, but sensitive to sage cover; vulnerable to cowbirds

sagebrush height

Sage thrasher

big sagebrush

sagebrush cover 5-20%; sagebrush height >80 cm; herb cover 5-20%; other shrub cover <10%; non-native herb cover <10%

>16 ha

(40 ac)


not area-sensitive ; not impacted by cowbirds; high moisture sites with tall shrubs

ecotonal edges herbaceous, shrub, tree habitats

Lark sparrow


bitterbrush, sagebrush

edge habitat with mosaic of growth forms where none exceeds 50% cover; open ground cover >20%




dry upland sites with minimal exotic weed cover; vulnerable to cowbird parasitism

sparsely vegetated desert scrub

black-throated sparrow

shadscale, spiny hopsage, budsage

shrub cover <20%; herbaceous cover <25%; open ground >40%; non-native herb cover <15%




dry upland sites with minimal exotic weed cover

scattered, mature juniper trees

ferruginous hawk

juniper

isolated, mature juniper trees >1/1.6 km; herbaceous-low shrub cover 15-60 cm tall




dependent upon prey (e.g., ground squirrels, jackrabbits); sensitive to human disturbance; 1 km buffer zone around nests

a Preferred species.

b Vegetative structure is a condensed version of the habitat objectives for each species. Refer to the text for more detailed description of habitat objectives.

Changes in forest habitat components have reduced habitat availability and quality for wildlife species dependent on timbered uplands. In natural landscapes stochastic events produce more complex landscapes than those found in managed forests. Variations in susceptibility to disturbance, weather patterns, and soil moisture result in forest patches of a variety of shapes, sizes, and stand age classes (McKelvey et al. 2000). This heterogeneity has been reduced through timber harvest and fire suppression in the subbasin. Dense stands of mid-seral Douglas fir and grand fir have increased in prominence while old growth forests and species like ponderosa pine and aspen have declined. Fuel loads have also increased due to fire suppression (Figure 39).



Snags and Down Wood


The prominence of snags and downed wood is a particularly important element of forest diversity that has been reduced in the subbasin. In the Blue Mountains of Oregon and Washington, nearly 100 different wildlife species of birds and mammals use dead and downed trees as sites for nesting, feeding, and perching. Nearly 60 species depend on suitable wildlife trees and associated cavities for their survival. Primary excavators such as the pileated woodpecker create holes in dead and dying trees that may be used later by secondary cavity users such as owls, bluebirds, wrens, and flying squirrels (U. S. Forest Service 1990).

Snags and woody debris are most common in old and mature forests that have declined in the region (Quigley and Arbelbide 1997; U. S. Forest Service 1990). A comparison of the coarse scale historic and current structural stage GIS layers developed by ICBEMP, indicates a decline in old growth forests and woodlands in the Umatilla/Willow subbasin of almost 97%. An analysis of the Upper Umatilla and Meacham Creek area using satellite imagery collected in 1991 found that 96% of trees in the area fell into the small pole or sapling size classes (0-20.9 DBH) (Umatilla National Forest 2000). Declines in mature forest habitat in the subbasin have likely contributed to population declines in many species including the vaux swift which nests in large hollow trees, and the goshawk which requires large trees to support its sizeable nest (Csuti et al. 1997). The Umatilla/Willow area was found to contain snag densities that met or exceeded the Forest Service established snag density objectives. However, and most importantly, large snags and snags in ponderosa pine forests had a density below Forest Service objectives. Overall high snag densities are attributed to recent insect outbreaks. While total numbers of snags may meet the Forest Services snag density objectives, because of their small size, many of these snags do not provide the cavity nesting habitat required by most snag dependent wildlife.


Dead and down wood is more abundant in true fir and mixed conifer stands across the subbasin, but less abundant in fire-regulated pine communities. Large-diameter trees will remain longer on the landscape than small-diameter trees. Dead wood densities will fluctuate across the landscape as a result of natural mortality. Snag and down wood abundance is subject to the frequency and intensity of large and small-scale disturbances such as fires, insects, disease, ice storms, and drought that have historically occurred throughout the area (Quigley and Arbelbide 1997).

Figure 39. Changes in fire frequency and severity in the Umatilla/Willow subbasin

Nutrient Flow Reduction

Spawning salmon populations form an important link between the aquatic, riparian, and terrestrial communities. Anadromous salmon help to maintain ecosystem productivity and may be regarded as a keystone species. Salmon runs input organic matter and nutrients to the trophic system through multiple pathways including direct consumption, excretion, decomposition, and primary production. Direct consumption occurs in the form of predation, parasitism, or scavenging of the live spawner, carcass, egg, or fry life stages. Carcass decomposition and the particulate and dissolved organic matter released by spawning fish deliver nutrients to primary producers (Cederholm et al. 2000). Cederholm identified nine wildlife species that have (or historically had) a strong consistent relationship with salmon; of these the common merganser, harlequin duck, osprey, bald eagle, Caspian tern, black bear, and northern river otter occur in the Umatilla/Willow subbasin. Eighty-three other wildlife species were identified as having a recurrent or indirect relationship with salmon, and many of these also occur in the Umatilla/Willow subbasin (Cederholm et al. 2000). The golden eagle, bald eagle, peregrine falcon, and bank swallow are among those that are state or federally listed/candidate species.

Exotic Species

Cheatgrass and Noxious Weeds


Disturbance of the grass and shrubland ecosystems by livestock has contributed to the spread of introduced grasses and weeds including cheatgrass (Bromus tectorum) and yellow starthistle (Centauria solstitialis). Early newspaper accounts from 1902 through 1923 describe wheat farmers in the Adams area of the Wildhorse Creek drainage having difficulties with “Russian thistle”, “tar weeds” and “Jim Hill Mustard” (Adams Ladies Club 1993 and 94). All 55 transects sampled by the WDFW on shrub steppe ecosystems in the Columbia basin contained exotic annual grasses and exotic forb species (Dobler et al. 1996). Kagan et al. (2000) reported that all shrub steppe and grassland habitats in the Lower Umatilla/Willow subbasin contained well-established populations of cheatgrass and/or medusahead (Tanaetherum caput-medusae).

The invasion of cheatgrass into shrub steppe habitats is especially problematic as it increases the frequency and severity of range fires (Paige and Ritter 1999). This change in fire regime is a result of cheatgrass growing at much higher densities compared to native vegetation (providing an unbroken flammable medium to carry fire), its property of drying out early in the season, and its ability to quickly reestablish itself after fire. In most instances, cheatgrass-dominated shrub steppe results in complete conversion to cheatgrass and other exotic weeds once the area burns. Sagebrush and other native shrubs take several years to decades to reestablish themselves after these intense fires. Since the cheatgrass returns quickly, and may burn as frequently as every five years, native shrubs have no opportunity to reestablish. The reestablishment of sagebrush in cheatgrass dominated rangelands is a major problem throughout the sagebrush zone of the Interior Western U.S., and no solution to the problem has been found. To date, the only method found for reestablishment is to plant individual sagebrush plants by hand, something that is not practical for any but the smallest areas.

Introduced plants in the subbasin often out compete native plant species, reducing the suitability of habitat available to the wildlife (Quigley and Arbelbide 1997). The most rapidly increasing exotic plants in the subbasin, and ones that are particularly problematic, are knapweed and yellow starthistle. These invader species are native to the Mediterranean, but have thrived in the subbasin due to similarities in climate between the two locations (Quigley and Arbelbide 1997). Both are widespread and rapidly invade areas that have been disturbed to replace native plant species. Other serious exotic species includes rush skeletonweed (Condrilla juncae), spikeweed (Hemizonia pungens), medusahead (Taeniatherum caput-medusae), and perennial pepperweed (Lepidium latifolium).

The diversity of terrestrial birds is positively correlated with plant diversity. Sage thrasher, sage sparrow, and white crowned sparrow occurrence is negatively correlated with percent cover of annual grass (Dobler et al. 1996). Columbian sharp-tailed grouse prefer eating native vegetation rather than introduced species, although cultivated grains supplement their diet (Hays et al. 1998)


Exotic plants are also a problem in riparian and wetland habitats. The most obvious of these is purple loosestrife (Lythrum salicaria), which is beginning to expand in wetlands along the Columbia River. Russian olive (Elaeagnus angustifolia) is a major problem in wet meadows and riparian areas to which it has escaped from residential plantings. While most rivers have lost all of their riparian tree and shrub cover, the few remaining areas have non-native forbs and grasses dominating the understory.

Bullfrogs


Bullfrogs are native to eastern North America. They were intentionally introduced to the western U. S as a game species. Bullfrogs have successfully colonized most of the lower elevation ponds marshes, rivers, and reservoirs of Washington and Oregon including many of those in the Umatilla/Willow subbasin. Numerous studies have shown that the bullfrog out competes native amphibians due to its aggressive behavior and rapid growth rate (Corkran and Thoms 1996; Charlotte Corkran personal communication February 2, 2001; Marc Hayes, WDFW, personal communication February 5, 2001). The bullfrog's preferred habitat is similar to that of many other amphibians native to the Umatilla/Willow subbasin, especially that of the Oregon spotted frog (Charlotte Corkran personal communication February 2, 2001; Mark Hayes, WDFW, personal communication February 5, 2001. Bullfrogs are voracious predators often eating the eggs, tadpoles, and adult members of native frog species. Bullfrog predation and competition is considered a major factor in the decline of many of these species (Csuti et al. 1997).

Virginia Opossum

The opossum is native to the eastern U. S.; they were introduced to Oregon between 1910 and 1920 and now occur within the Umatilla/Willow subbasin. Opossum are opportunistic feeders and consume a variety of small birds, mammals, and reptiles (Csuti et al. 1997). Opossum predation on bird eggs may be limiting native bird population and is a concern for wildlife managers in the subbasin.


Hydropower System Development and Operations


The development and operation of dams for hydropower, navigation, flood control, and irrigation in the Columbia River basin resulted in widespread changes in riparian riverine and upland habitats. Documented losses from studies conducted in the late 1980s associated with each hydropower facility are provided in Table 46 (Susan Barnes, ODFW, personal communication February 2001).
Table 46. Habitat losses associated with hydropower development


Hydropower Facility

Habitat Acres Inundated

Habitat Units Lost

Bonneville

20,749

12,317

The Dalles

1,923

2,230

John Day

27,455

14,398

McNary

15,502

19,397

Hydropower development has resulted in urban expansion, numerous roads and railways, and other structures. The creation of reservoirs has permitted the expansion of irrigation, thus resulting in extensive habitat conversion. The frequency and duration of water level changes has influenced vegetation succession on islands and along shorelines. In some cases these fluctuating water levels have created barren vegetation zones and exposed wildlife to increased predation. Low water levels create land bridges that provide predators access to nesting islands. For example, inundation of gravel bars and sandy islands reduced the available area for nesting and resting waterfowl. Other results of hydropower development and operation often include the draining and filling of wetlands, stream channelization, shoreline riprapping, construction and maintenance of transmission power corridors, increased access to and harassment of wildlife, and increased erosion and sedimentation in the Columbia River and its tributaries.

The construction of McNary Dam made possible the irrigation of about 244,000 acres of land in Oregon and Washington, a portion of which falls within the Umatilla/Willow subbasin (Susan Barnes, ODFW, personal communication February 2001).


Land Protection Status


Eighty-nine percent of the subbasin is privately owned (Figure 18). This makes providing long term stable wildlife habitat challenging and increases interactions between wildlife and the public. For example 83% of the winter elk range in the subbasin is privately owned, and most of this land is grazed or farmed. Elk populations at target population levels (ODFW 1986) use privately owned winter range extensively (Table 47). Elk winter use of grazing and agricultural land often causes property damage (Oregon Department of Fish and Wildlife 1992b). Such damage results in pressure on ODFW to reduce the elk population. These pressures could largely be alleviated if winter range areas receiving high levels of use were in protected status and managed for wild ungulate winter range quality.

Table 47. Elk densities at management objective level in the Umatilla/Willow subbasin




Average Elk Density at Management Objective Level

Winter Range




Summer Range




Total

Public

Private

Total

Public

Private


18.9

22.9

16.7

11.1

11.5

10.0

Acquiring and protecting important wildlife habitat areas in the subbasin is a management priority. A large proportion of habitat within the Umatilla/ Willow subbasin is privately owned (Table 48). Maintaining and increasing the lands registered under the CRP program is crucial to this effort, particularly if sharp-tailed grouse are to be reintroduced to the subbasin, since most of their potential habitat is on privately owned lands (Kagan et al. 2000). Land acquisition efforts are hindered by the steadily rising cost of land in the subbasin. Opportunities to restore wildlife populations and improve habitat diminish over time as habitat loss and degradation continues (Susan Barnes, ODFW, personal communication February 2001)


Table 48. Percentages of privately owned habitat in the Umatilla/Willow subbasin (Kagan et al. 2000).


Cover Type

Percent of Total Area

Privately Owned



Big Sage/Bluebunch Wheatgrass

66

Big Sage/Idaho Fescue

98

Big Sagebrush Steppe


77

Bitterbrush Shrub Steppe

54

Bluebunch Wheatgrass

92

Forest

95

Hawthorne Snowberry/Fescue

100

Idaho Fescue

99

Needle & Thread Grassland

20

Rigid Sage/Sandberg Bluegrass

81



Species-Specific Limiting Factors


  • MacGillivray’s Warbler (Altman and Holmes 2000a, 2000b)

  • Loss of brushy habitat in the understory of mixed conifer stands

  • Reduced shrub cover due to grazing intensity, wildfires, and herbicide use



Flammulated Owl (Altman and Holmes 2000a, 2000b)


  • Loss of mature and old growth trees and snags for nesting and roosting

  • Loss of open understory because of invasion of exotics and fire intolerant species

  • Reduction in the availability of small dense thickets for roosting



White-Headed Woodpecker (Wisdom et al. 2000)

  • Declines in late seral ponderosa pine for nest cavities


  • Loss of large diameter snags

  • Decline in old aspen cottonwood and willow stands



Canada Lynx (Ruggiero et al. 1999)


  • Lack of suitable foraging, denning, or travel habitat

  • Inadequate juxtaposition of forage, denning or travel habitat

  • Inadequate prey species availability

  • Human interaction (trapping, highways, urbanization, etc.)



Wolverine (Witmer et al. 1998)


  • Insufficient amounts of remote forest habitats.

  • Insufficient rock and talus areas for natal dens

  • Human interaction (trapping, highways, urbanization, etc.)



Wetland and Riparian-Dependent Species

Columbian Spotted Frog (Marcot et al. 1997, McAllister and Leonard 1997)


  • Loss of wetlands and changes in plant community structure

  • Insufficient aquatic vegetation for cover and foraging

  • Limited amounts of down wood and woody debris in wetland habitats

  • The spread of exotic aquatic predators like bullfrogs and warm water fishes



Northern Leopard Frog


  • Loss of wetlands and changes in plant community structure

  • The spread of exotic aquatic predators like bullfrogs and warm water fishes



Red-Eyed Vireo (Altman and Holmes 2000a, 2000b)


  • Reduced shrub understory
  • Livestock grazing in riparian habitat due to reductions in insect productivity and recruitment of young cottonwoods




Bald Eagle (Bureau of Land Management and U. S. Fish and Wildlife Service 1986)


  • Reduced late and old structure along major tributaries.

  • Disturbance around potential nesting and roosting habitat (riparian corridors)



Managed Species

Elk


  • Winter range, particularly on publicly owned protected areas

  • Noxious weeds and poor range conditions



Blue Grouse(Larsen and Nordstrom 1999)


  • Reforestation practices that include high density replanting and herbicide application

  • Intense grazing of open lowland forests in drier areas



Mountain Quail (Larsen and Nordstrom 1999)


  • Intense grazing of open lowland forests in drier areas

  • Inadequate food supply caused by habitat loss

  • Loss of winter habitat from dams and water impoundments

  • Loss of riparian connectivity



Extirpated Species

Sharp-Tailed Grouse


  • Loss of riparian connectivity

  • Loss of stable protected shrub steppe habitat (Crawford and Coggins 2000)

  • Loss of shrub species such as serviceberry (Amelanchier alnifolia), chokecherry (Prunus virginiana), and hawthorn (Crategus douglassi) for food and cover



Big Horn Sheep


  • Domestic sheep

  • Loss of rocky outcroppings




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