Western meadowlark

©Dan Dzurisin

Chapter 4 Biological Environment

Chapter 4BiologicalEnvironment

Chapter 3PhysicalEnvironment

Chapter 1Introduction andBackground

Chapter 5HumanEnvironment Maps

Chapter 2Management Direction Appendices

Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-1 

Chapter 4. Biological Environment 

This chapter addresses the biological resources and habitats found on the Refuge. However, it is not 

an exhaustive overview of all species and habitats. The chapter begins with a discussion of biological 

integrity (historic conditions and ecosystem function), as required under the Improvement Act. The 

bulk of the chapter is then focused on the presentation of pertinent background information for 

habitats used by each of the priority resources of concern (ROCs) and other benefitting species 

designated under the CCP. That background information includes descriptions, conditions, and trends 

of habitats and threats (stresses and sources of stress) to the habitats and/or associated ROCs. This 

information was used to develop goals and objectives for the CCP. 

4.1 Biological Integrity, Diversity, and Environmental Health 

The National Wildlife Refuge System Administration Act (as amended) requires the maintenance of 

the biological integrity, diversity, and environmental health (BIDEH) of the System. The BIDEH 

policy (601 FW 3) defines biological integrity as “the biotic composition, structure, and functioning 

at genetic, organism, and community levels comparable with historic conditions, including the 

natural biological processes that shape genomes, organisms, and communities.” Biological diversity

is defined as “the variety of life and its processes, including the variety of living organisms, the 

genetic differences among them, and communities and ecosystems in which they occur.” Simply 

stated, BIDEH is represented by native fish, wildlife, plants, and their habitats as well as those 

environmental conditions and processes that support them. The Administration Act states that each 

refuge will be managed to fulfill refuge purpose(s) as well as to help fulfill the System mission. We 

strive to accomplish these purposes and our mission by ensuring that the biological integrity, 

diversity, and environmental health of Malheur Refuge is maintained and enhanced. 

The Refuge System policy on BIDEH (601 FW 3) also provides guidance on consideration and 

protection of the broad spectrum of fish, wildlife, and habitat resources found on the refuges and in 

associated ecosystems, that represents BIDEH on each refuge. 

4.1.1 Overview 

Throughout this document, the concept of a healthy system (either aquatic or terrestrial) is the goal or 

direction the Refuge wishes to take in habitat management. The Refuge defines a healthy system as a 

landscape, land unit, or habitat in which natural ecological processes function in concert to permit an 

area to be productive and have a fundamentally dynamic nature. These interacting processes result in 

a mosaic of communities that are resilient to disturbances but that change over time along the 

ecological continuum defined by the Ecology Work Group (Appendix L). This result ensures 

balance, appropriate niches, or natural variation necessary for the wide array of potential wildlife 

species that could use the area. The refuge goal of restoring or maintaining the resiliency of this 

system and understanding the importance of all the components or needs of wildlife (migration, 

production, and maintenance habitat) ensures the richness necessary to maintain a healthy system, 

provide for the wide diversity of wildlife that use the area, and allow the area to buffer or absorb 

impacts from major disturbances. 

Malheur National Wildlife Refuge is composed of three very distinct environments, each including a 

diversity of native habitats and landscapes. The core of the Refuge is dominated by a shallow lake 

basin and encompasses Harney, Mud, and Malheur lakes. This 103,799-acre area covers 56 percent 

of refuge lands. The Blitzen Valley, a broad corridor (64,215 acres) to the south of the lake basin, is 

divided along its entire length by the Blitzen River and associated riparian habitat. The valley covers 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-2 Chapter 4. Biological Environment 

34 percent of the Refuge and provides most of the water feeding the central lake basin. The DoubleO is a broad valley basin which covers 10 percent (19,198 acres) of refuge lands. Intermittent water 

from the Silver Creek watershed flows through this management area and drains into Harney Lake 

(see Chapter 3). Together, these three environments result in a diversity of habitats, which support 

more than 415 species of birds, mammals, fish, reptiles, and amphibians. 

4.1.2 Wildlife and Habitat Conditions and Changes Since 1800 

The Harney Basin ecosystem, of which the Refuge is a part, has undergone dramatic alteration over 

the past 200 years. Three of the most discernible changes are 

 changes in Harney Basin lake and river hydrology due to diversion dam and irrigation 

operations; 

 changes to species composition (decline and loss of native species and influx of non-native 

and invasive species) into the system; and 

 conversion of basin habitats to agricultural and ranching lands (including diking and 

irrigation). 

Many of the habitat changes and the spread of non-native and invasive species were underway long 

before the Refuge was established. This section discusses the connection between these landscapelevel changes and the current vegetation and wildlife on the land and waters managed by the Refuge. 

This summary is not a complete analysis of all factors related to changes in native vegetation, fish, 

and wildlife. Much of the information presented here is based on staff knowledge of the area. 

Historic Description of Habitat and Wildlife 

Historically the Blitzen and Double-O valleys, along with the lake basin located within the refuge 

boundary, had a much different appearance than they do today. Wigand’s work (Wigand 1987) on 

the vegetation and water table history of Diamond Pond, located in the Diamond Craters, illustrates 

the constant flux and change in water levels which prevailed in the area prehistorically. Between 

1400 and 900 B.P., increased grass pollen signified greater effective moisture resulting in deeper 

water with abundant pondweed (Potamogeton sp.). Increased greasewood and saltbush pollen around 

500 B.P. provide evidence of drought conditions. Widgeongrass (Ruppia sp.) seeds and pollen and 

the presence of bivalve mollusk (Musculium sp.) shells indicate shallow brackish water. Abundant 

juniper and grass pollen samples indicate moister conditions from 300 to 150 B.P. Numerous 

hornwort fruits (Ceratophyllum sp.) indicate deeper, freshened water during this period. The last 

cycle, sampled from the mid-1880s, showed another climate change with sagebrush re-expansion and 

increased sedge (Scirpus sp.) macrofossils indicating shallower water. 

Fur trapper Peter Skene Ogden’s journal of 1826 describes the lakes portion of the Harney Basin as 

swampy country with flat terrain and rivers flowing into two lakes with no outlet (see Section 5.1.2). 

Eli Cooley’s diary of 1845 (Cooley and Cooley 2004) describes the vegetation along the lower 

Silvies River as plenty of grass and willow. As their wagon train moved west along the north side of 

Malheur Lake, cutting across the end of Wright’s Point and camping by Harney Lake, the habitat was 

described as plenty of grass, no wood, and some sage. As they moved upstream along Silver Creek 

before crossing it and turning west, the area was again defined as having plenty of grass and willow. 

The 1853 journal of wagon train emigrant Benjamin Owen labeled the lower Blitzen River as a deep 

miry stream. They had trouble finding a suitable ford and had to travel over 5 miles (in the vicinity of 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-3 

Rattlesnake Butte) upstream to secure a safe crossing for their wagons and livestock (Beckham 

1995). 

The Wallen party of 1859 moved through the basin on the north side of Malheur Lake and described 

the area as follows: “the country is a beautiful level valley, covered with luxuriant growth of bunch 

grass, wild pea vines, and red clover, interspersed with fields of camas on a rich soil abundantly 

watered by numerous mountain streams .... This wide savannah or grassy meadow section is 

abundant; pronghorm, deer, elk, and several species of grouse, prairie chickens, ducks and geese, 

etc.” (Beckham 1995). 

Langston provides a historical perspective of habitat conditions before substantial alterations by 

settlers in her book entitled Where Land & Water Meet: a Western Landscape Transformed

(Langston 2003). She states that when Peter French first arrived in the Blitzen Valley in the early 

1870s, he found “a water world: a maze of streams, channels, wetlands, bogs, alkaline lakes, and lush 

riparian meadows—all fed by waters from the Blitzen River.” She also documents that in a 1935 

radio talk show, William L. Finley stated, “Peter French ... wandered into what is now known as the 

Blitzen Valley, a wide flat plain watered by a fine stream, green with wide meadows of luxuriant 

grasses, interspersed with thickets of willow, and with great areas of swampy ground and shallow 

ponds.” Moreover, tule marshes characterized extremely wet areas surrounding the P Ranch at the 

southern end of the Blitzen Valley. In fact, French noted that his livestock took cover in tules during 

extreme winter weather (Langston 2003). 

Documentation of vegetation prior to Euro-American settlement is sketchy, existing only in the form 

of broad-sweeping descriptions caught in diaries and correspondence. Nevertheless, combining these 

references with soils information and comparisons with similar systems within the Northern Great 

Basin suggests that the area hosted a complex, heterogeneous mixture of plant species ranging from 

cattails and bulrushes in permanent marshes to dryland grasses, forbs, and shrubs in highland areas 

with rushes, sedges, and wetland grasses appearing along moisture gradients. 

Changes to Harney Basin Hydrology, Wildlife, and Habitats Since 1850 

Although people were present in Harney Basin prior to the 1850s, human influences were probably 

limited to minimal impacts by Northern Paiutes, fur-trapping expeditions, and settlers moving by 

wagon train through the area. Beckham’s (1995) document on the historical appearance and uses of 

the Donner und Blitzen River from its headwaters to the confluence with Malheur Lake shows the 

trend of changes that have occurred throughout the basin over time. 

In the 1870s stockmen poured into the rangelands of the Harney Basin claiming all the primary water 

sources and thus dominating the surrounding lands. Meanwhile, the State of Oregon was accepting 

applications to purchase tracts of swamplands and in the 1880’s began issuing deeds. Peter French 

and other cattlemen acquired control of these deeds throughout the basin. This initiated an ambitious 

period of irrigations projects, first in the Blitzen River Valley but soon expanding to other waterways 

in the basin. Water was diverted into canals and ditches, flooding out sagebrush and inducing the 

growth of meadow grasses. This heavy irrigation had dramatic effect on basin landscapes, affecting 

not only uplands, but wetlands and the lakes. Giles French wrote of Peter French’s irrigation projects: 

“His irrigation projects of themselves held water of Malheur Lake at a lower level, causing more dry 

land between the water and the meander line” (French 1964). 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-4 Chapter 4. Biological Environment 

The Blitzen River has undergone significant alterations since the late 1800s. The construction of an 

intensive irrigation system, including seven diversion dams and a vast network of ditches, dikes, and 

ponds, was initiated under the management of Peter French and reached its peak during the CCC era 

following the Great Depression. The channelization of approximately 17.5 miles of the Blitzen River 

between Bridge Creek and Busse Dam also took place prior to Federal acquisition in 1935. Human 

activity in its various forms has disrupted the natural hydrology of historic river meanders and 

smaller braided tributaries; however, the ability to move irrigation water around the Blitzen Valley 

via canals and ditches has expanded wetland habitats that would not otherwise exist. 

Changes to Species Composition: Irrigation and livestock grazing have had a profound impact on 

basin habitats and wildlife. Native grasses and forbs are not adapted to heavy grazing pressure or 

extended irrigation and have become susceptible to the spread of exotic plant species in many areas. 

Non-native pasture and forage grasses were also introduced. These grasses had a competitive 

advantage over native species under heavy grazing or irrigation pressure and thus altered many plant 

communities. Increased and improved irrigation around riparian areas permitted reed canarygrass to 

invade and largely replace the native understory plant community. Today, areas within irrigated 

meadows are dominated by creeping wildrye, orchardgrass, timothy, smooth brome, Nebraska sedge, 

meadow foxtail, and reed canarygrass. Creeping wildrye and Nebraska sedge are native species, but 

the remainder have been introduced to the area and did not occur before European settlement. These 

two factors were the beginning of the decline of wildlife species tied to upland or riparian habitats 

such as the yellow-breasted chat, willow flycatcher, meadowlark, and bobolink. On the other hand, 

grazing may have benefited other wildlife species such as greater sandhill cranes, horned larks, and 

snow geese. The positioning of wetlands, pasture, and croplands may have actually helped sustain 

populations of waterfowl and other birds that prefer short, nutritious grass. 

Interruption of ecological function on the Blitzen River, Silvies River, and Silver Creek also had a 

profound impact on fish species. Channelization destroyed habitat complexity on large reaches of 

these waterways and is believed to have reduced the abundance of fish species. Barriers prevented or 

delayed migratory fish patterns and isolated portions of some populations. Altered water parameters 

such as water quality have pushed some species such as mountain whitefish to the least disturbed 

stretches of these streams. The increase in human disturbance has also naturally led to the 

introduction of exotic species such as sunfish, bluegills, large-mouth bass, and bullheads. 

Conversion of Basin Habitats to Agricultural and Ranching Lands: At the close of the 1800s and 

the beginning of the new century, homesteaders moved onto lands below the Malheur Lake meander 

line, leading to conflict between ranchers and these new immigrants. During this time, heavy use was 

made of the lake bottom by large and small ranching operations for grazing, haying, and crops. 

During the same time frame, women’s millinery fashions created a major market for plume hunters, 

who decimated populations of herons and egrets on Malheur Lake. 

It was in this altered environment that Malheur National Wildlife Refuge was established in 1908. As 

a result of the outrage over the decimation of colonial nesting birds on Malheur Lake, President 

Theodore Roosevelt set aside unclaimed government lands encompassed by Malheur, Mud, and 

Harney lakes. 

4.1.3 History of Refuge Management 

As discussed in Chapter 1, the purposes of the Refuge primarily pertain to the perpetuation of 

breeding birds, migratory birds, and other wildlife. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-5 

Malheur Refuge lies in the shrub-steppe association of the Basin and Range Province of Oregon 

(Bailey et al. 1994) and hosts a significant portion of riparian and floodplain habitats (wet meadows 

and marshes) that are under-represented and degraded throughout this ecoregion. It is one of the 

oldest and most important migratory bird refuges in the Refuge System. It has long been recognized 

for its contribution to the Pacific Flyway as a major and essential feeding and resting location for 

Pacific Flyway birds migrating between the northern breeding grounds and wintering areas to the 

south. It is also an important breeding ground for wetland-dependent migratory birds. 

The maintenance and enhancement of wetland systems occurring within the Refuge contributes not 

only to management for refuge purposes but also to biological integrity at multiple landscape levels. 

On the larger landscape scale, it is important to migratory birds on the Pacific Flyway. At the local 

scale, the area is significant because of native wetland and riparian plant communities and their value 

to resident wildlife. At the same time, the Service recognizes that wetland management should be 

balanced with the habitat requirements of native fishes (redband trout) and the need to improve water 

quality. 

After the Refuge was established the Refuge remained unstaffed until 1911, when State game 

wardens were assigned to enforce State hunting and trapping laws. It was not until 1915 that data 

were finally compiled about lake levels and bird populations. Considerable time was spent banding 

waterfowl after 1920, and these records were used to determine bird population trends on the lakes. 

In the 1930s, drought had a profound effect on the basin; with decreased flows from rivers and 

streams, lake levels shrank. Without a fence around the Refuge, the sole refuge employee spent 

considerable time keeping adjacent landowners from using refuge lands for agricultural purposes. 

Resolution to this issue came in 1935 when the Blitzen Valley was added to the Refuge. Acquisition 

of water rights for the Blitzen River allowed the release of water to the lakes that had previously been 

kept behind ranch dams. 

William Finley described the Blitzen Valley and lake condition at that time as 

a wide flat plain watered by a fine stream, green with wide meadows of luxuriant 

grasses, interspersed with thickets of willow, and with great areas of swampy 

ground and shallow ponds. ... Within the boundaries of this refuge such favorite 

waterfowl as Canada geese, Mallards, Pintails, Gadwall, Redheads, Ruddy Ducks 

and Cinnamon Teal nest and rear their young by the thousands, while during the 

fall and spring migrations myriads of northern-bred ducks and geese find a haven 

of refuge on Malheur Lake and in the swamps of the Blitzen Valley where natural 

food is abundant. Not only are ducks and geese found here but the great American 

egret, the White-faced Glossy Ibis, and the Black-necked Stilt.... Herons, bitterns, 

coots, grebes, and great colonies of California and Ring-billed gulls, Forester 

Terns, Black Terns and other marsh-loving birds held interest of the visitor. ... Of 

upland game and song birds there is an unusual population. Sage hens stalk about 

the sagebrush covered slopes, and the California or Valley Quail scurry under the 

tickets. The introduced Hungarian Partridge and the Ring-necked Pheasant find the 

climatic conditions here to their liking. ... Although birds, both in number of 

species and the number of individuals, form the greatest of the wildlife population, 

the visitor can find a large number of beaver along the Blitzen River. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-6 Chapter 4. Biological Environment 

Nationwide waterfowl numbers had declined so rapidly because of widespread drought that Federal 

funds were allotted to restore breeding and feeding areas. Malheur Lake was given high priority, and 

thus began the era of the Civilian Conservation Corps and major refuge restoration projects. Projects 

included the construction of Refuge Headquarters, boundary fences, dikes (to better conserve water 

for both the lakes and valley), canals (to carry water to favored feeding grounds), and roads (to better 

patrol the area). The water delivery system within the Blitzen River Valley was developed or 

enhanced to provide water for new wetlands (Boca, Benson, Knox, Wright, and Buena Vista ponds). 

Although most of the projects were considered very beneficial to restoring water to the lakes and 

wetlands, some of the projects continued the disruption of the natural hydrological processes in the 

basin, such as replacement of five wooden diversion dams with concrete diversion dams, which 

included fish ladders. In addition, when some projects were combined with other human impacts, 

such as grazing and irrigations practices, whole plant communities were altered. The Refuge 

developed a cropland management program to provide carbohydrate-rich crops for fall migrants, 

particularly waterfowl and cranes. 

The 1940s and 1950s saw the next major change to Harney Basin ecology and impacts to the Refuge, 

with the introduction of common carp to the Silvies River. Carp spread throughout the system in a 

very short period of time and altered wetland systems by uprooting submergent and emergent 

vegetation, increasing turbidity, and exposing wetlands to wind and wave erosion. This had a 

tremendous impact on the number of birds using Malheur Lake, particularly waterfowl and other 

wetland nesting and feeding species. Intermittent attempts to eradicate carp were carried out in 1955, 

1961, 1968, and periodically since then. Control efforts showed positive results for one to two years 

after treatment until population dynamics re-established carp in treated areas. 

Other management activities during this period saw the third major addition to the Refuge with the 

purchase of the Double-O Unit to provide habitat for shorebirds, waterbirds, and waterfowl. Grazing 

was used as a management tool to maintain short-grass habitat for waterfowl, cranes, and other 

grasslands nesting species. Rainbow trout were introduced into Krumbo Reservoir (constructed in the 

mid-1950s), and trumpeter swans were reintroduced to the Refuge. 

In the 1970s, the Refuge shifted its management direction to bring activities in line with new Service 

directives by developing a refuge land use plan for habitat management. This called for a shift in 

management actions by reducing the amount of cattle grazing on the Refuge and providing other 

tools to maintain short grass or meadow habitat. Management actions to control exotic and invasive 

species were initiated. Formal survey procedure and protocols were developed to monitor habitat and 

wildlife. All these changes were part of a move to support greater conservation of resources under 

new national policies. 

Higher-than-normal precipitation levels in the 1980s resulted in extensive flooding throughout the 

basin and the subsequent destruction of infrastructure and habitat. With the high water and the 

deleterious effects of carp on Malheur Lake, conditions were in place to accelerate destruction of 

Malheur Lake ecology. Wind, waves, and ice scoured the lake substrate, creating a shallow uniform 

lake bottom in which sediments never settled and emergent and submergent vegetation became 

mostly absent from the central portion of Malheur Lake. With the loss of emergent vegetation, the 

muskrat population on the lake was drastically reduced and to date has not recovered. Refuge staff 

was also charged with developing a master plan for the Refuge. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-7 

As quickly as the water rose in the 1980s, the lake rapidly diminished in the early 1990s, with 

watering covering just a few thousand acres in the center of the lake. This shift sharply curtailed 

wildlife use of the lake. From the 1990s onward, the Refuge continued to repair the damage to 

habitats and infrastructure and provide for wildlife needs in the Blitzen Valley while waiting for 

increased precipitation events to restore water to Malheur Lake. 

Fish passage, screening, and fish traps became an important issue trying to ensure passage of Great 

Basin redband trout over the dams on the river while preventing movement of carp through the 

system. The concrete fish ladders in operation since the dams were constructed were retrofitted with 

new denil-style fish passage structures. Screens were placed on a number of diversion canals and 

ditches to prevent entrainment of native fishes and decrease spawning areas for invasive carp in 

fields, ponds, and ditches. Fish traps were manufactured and fitted at the top of the fish ladders to 

sort carp from the native fish moving upstream on migration. Fish screens were installed on the 

diversion of the East Canal. A fish screen and passage structure was installed on the Blitzen River at 

the West Canal diversion to prevent entrainment of fish into the irrigation ditch and permit passage 

of fish up and down the mainstem of the Blitzen River. Research conducted by Matt Anderson 

concluded that fish passage and screening on the Blitzen River was not optimal for the native 

redband trout (Anderson 2009). Therefore, ODFW recommended that new fish ladders be installed. 

In 2009, construction of three new fish ladders and screens was started to improve fish passage and 

screening and was complete in 2012. 

The Refuge put a greater emphasis on controlling exotic and invasive species as infestations 

increased in size. Fire became a more active management tool for enhancing wetland, meadows, and 

grassland habitats through the removal of decadent growth, reduction in fuel loads, and setting back 

undesired vegetation. With degradation of the lake ecosystem, an emphasis was placed on 

maintaining water on wetlands units and meadows for as long as possible to maximize production for 

all species of waterfowl, cranes, and other birds that use these habitats. This had the desired outcome, 

and production has been sustained at very high levels. However, maintaining water on these habitats 

has also provided ideal conditions for water-tolerant plant species and a competitive advantage to the 

exclusion of other species, resulting in dense monotypic stands of emergent vegetation and 

encroachments into meadow habitats. 

Restoration efforts focused on riparian and riverine habitats. Canals and ditches were fenced to 

reduce erosion from cattle and to provide an opportunity for re-establishment of riparian plants. The 

upper Blitzen River was the site of a restoration project in which inverted rock weirs were staggered 

over a 5- mile length of river between the P Ranch and the confluence of the river with Bridge Creek. 

The restoration project was intended to create in-stream and riparian habitats, reconnect the river to 

the floodplain, and raise the level of the deeply incised river. Assessments of the effect and success 

of this project are still being conducted. 

4.1.4 Changes in Species Composition of Wildlife Populations after Refuge 

Establishment 

Hydrologic Changes that Led to Altered Habitats 

It can be hypothesized that the greatest difference between plant community conditions prior to EuroAmerican settlement and current conditions can be directly correlated with the extent and availability 

of water. Prior to hydrological modifications (ditches, dams, and the channelization of 17.5 miles of 

the Blitzen River, as well as the rerouting and damming of Silver Creek in the Double-O Unit), 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-8 Chapter 4. Biological Environment 

concentrations of plants would have been dependent on the level of flooding that occurred in 

conjunction with topographic features. Beckham (1995) believes that the Blitzen Valley once hosted 

a much higher percentage of upland and meadow plant communities, such as basin big sagebrush, 

bluebunch wheatgrass, and basin wildrye, than exist today. 

After settlement, some uplands and meadows were leveled to maximize efficiency of flood irrigation, 

which was provided by a complex system of diversion dams and ditches, and to facilitate the 

production of grain and grasses. Under current refuge management an emphasis on extended 

irrigation in these areas provides ideal conditions for water-tolerant plant species, and some sites 

have become dominated by such species as cattails, phragmites, and reed canarygrass. However, 

extended irrigation has also encouraged the re-establishment of woody riparian species, such as 

willow, to some of its historic range. 

Although historic numbers for waterfowl in the Blitzen Valley and Double-O are not available, it is 

likely that construction of the water-delivery systems and the managed impoundments and wet 

meadows in these irrigated units led to increased numbers of breeding waterfowl, cranes, and 

shorebirds. However, this benefit to waterfowl could not compensate for the loss of quality 

waterfowl habitat in Malheur and Mud lakes because of invasive carp. 

When refuge grain fields were abundant, use of the valley by migrant geese and ducks was very high 

with peaks in the hundred-thousands. However, as the grain fields were converted back to irrigated 

meadows, high use by migrants diminished. 

Gabrielson and Jewett (1940) stated that the greater sandhill crane was rapidly disappearing from 

Oregon in the late 1930s and estimated that the remaining flock numbered only about 100 pairs in the 

Blitzen Valley and east of Steens Mountain. The Blitzen Valley was a stronghold for crane survival 

during the era of unregulated market hunting. By the late 1990s, the refuge crane population had 

increased to 245 pairs (Ivey and Herziger 2000). Migrant crane use of refuge grain fields increased 

over time as populations recovered from unregulated hunting and peaked in the early 1980s at 

approximately 3,500. However, during the flood years of the mid-1980s and the subsequent droughts 

in 1988 and 1992, refuge grain crops were poor, and fall crane use declined to less than 10 percent of 

the peak and has remained low. 

While nesting colonial waterbirds were historically abundant in Malheur Lake, there is no evidence 

that colonial waterbirds were nesting in the Blitzen Valley or Double-O units before refuge 

acquisition and subsequent development of large impoundments. Today, managed impoundments 

support substantial numbers (numbering in the thousands in good years) of nesting white-faced ibis, 

Franklin’s gulls, and eared grebes. 

It is likely that changes to the Blitzen River hydrology have caused significant declines in the 

carrying capacity of the river for native fishes, mollusks, and other aquatic species. Development of 

the irrigation system contributed to lower water quality (primarily water temperature) and eliminated 

connectivity between many braided channels in the valley, significantly reducing aquatic and riverine 

habitat diversity and availability for aquatic fauna. This loss of extensive riverine habitat may also 

have had a major impact on local beaver populations. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-9 

Influx of Exotic and Invasive Species 

Exotic plants and animal invasions are a serious threat to the biological integrity of the Refuge. 

Invasive plant species displace native vegetation, alter the composition and structure of vegetation 

communities, affect food webs, and modify ecosystem processes (Olson 1999). Ultimately, invasive 

plant and animal species can result in considerable impacts to native wildlife. Common carp are 

believed to have had the largest impact to habitat and wildlife, causing reduced migratory bird use of 

the Refuge. 

Exotic Plants in Riparian and Wetland Systems: Exotic invasive plants that have proliferated in 

riparian and wetland areas include perennial pepperweed, reed canarygrass, Canada thistle, and 

Russian olive. Common reed is also present on a much smaller scale in some wetland units. All of 

these species displace native plant communities and reduce the habitat values for many wildlife 

species. For example, reed canarygrass forms tall, dense, almost impenetrable stands, which have 

almost no value for nesting birds and other wildlife. 

Exotic Species in Aquatic Systems: The Harney Basin supports fish mirroring the native fishes of the 

Columbia River with a few species absent or undetected, before they disappeared. (As noted in 

Chapter 3, the basin was connected thousands of years ago to the Columbia River drainage.) Since 

Euro-American settlement, a variety of warm-water fish species have been introduced to the basin to 

increase the diversity and quality of recreational angling. Many of these introduced fish prey on 

native species and/or compete with them for food resources. Common carp were introduced into the 

Silvies River in the 1920s and invaded Malheur Lake in the late 1940s, becoming a noticeable 

problem in the early 1950s. Their presence has resulted in devastation of aquatic plant and 

invertebrate communities, reduced water quality, and increased turbidity, and they have caused a 

large reduction in waterfowl use and production on the lake (Ivey et al. 1998). Carp have also spread 

or have the potential to spread to most of the aquatic systems of the Blitzen Valley and the Silver 

Creek drainages. A small established population of bullfrogs located at the south end of the Blitzen 

Valley could threaten the Refuge’s population of Columbia spotted frog by predation, loss of habitat, 

and food resources. 

A number of non-native fish have been recorded in various surveys on the Refuge. These fish include 

common carp, rainbow trout (Oncorhynchus mykiss), mosquito fish (Gambusia affinis), yellow 

bullhead (Ictalurus natalis), brown bullhead (Ictalurus nebulosus), black bullhead (Ameiurus melas), 

largemouth bass (Micropterus salmoides), green sunfish (Lepomis cyanellus), bluegill (Lepomis 

macrochirus), pumpkinseed (Lepomis gibbosus), white crappie (Pomoxis annularis), and yellow 

perch (Perca flavescens). 

Exotic Plants in Upland Systems: Major invasive weeds that have invaded refuge upland habitats 

include perennial pepperweed, Russian knapweed, and whitetop. These species occupy a large 

percentage of lowland shrub communities and have replaced native grasslands and forbs, which are 

important to native animals, such as small mammals. More recently, medusahead has invaded shrub 

lands on the southernmost portion of the Refuge (approximately 30 acres). 

Control Efforts: An IPM approach is used, which includes a variety of tools such as 

mechanical/physical control methods, cultural control methods, biological control, pesticides, habitat 

restoration, and protocols preventing new introductions (see Appendix G, Integrated Pest 

Management Plan). Control efforts are planned annually, and Pesticide Use Proposals (PUPs) are 

submitted to regional and/or national IPM coordinators for approval. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-10 Chapter 4. Biological Environment 

Mechanical, physical, biological, and chemical methods have been used to combat invasive plants in 

a variety of habitats. Biological methods have included prescribed use of cattle and sheep grazing 

and prescribed burning. Insects introduced for biological control include thistle stem gall flies, thistle 

beetles, and thistle weevils for Canada thistle. Considerable progress has been made with infestations 

of Russian olive around Malheur Lake, using burning, grazing, and chemical control. 

Much effort has focused on controlling carp. Annual wetland management plans prescribe 

drawdowns of impoundments to kill carp; traps have been placed in major dams to prevent their 

migration upstream; various types of netting techniques have been used for removal and population 

assessments and electroshocking has been used to remove them from some areas. Rotenone, a 

piscicide, has been used to supplement other measures of carp control. Several large-scale rotenone 

projects were conducted on the Refuge during years when lake levels were low and such treatments 

were deemed cost-effective. These treatments resulted in temporary increases in waterfowl use 

before the carp population rebounded. 

4.2 Priority Resources of Concern 

A key step in biological planning involves selection of priority ROCs (sometimes called conservation 

targets in other planning methodologies). These priority ROCs framed the development of the CCP’s 

goals and objectives for wildlife and habitat. 

4.2.1 Selection Process 

Resources of concern, as recommended under the Service’s Habitat Management Planning policy 

(620 FW 1), include: 

all plant and/or animal species, species groups, or communities specifically 

identified in refuge purpose(s), System mission, or international, national, 

regional, State, or ecosystem conservation plans or acts. For example, waterfowl 

and shorebirds are a resource of concern on a refuge whose purpose is to protect 

“migrating waterfowl and shorebirds.” Federal or State threatened and endangered 

species on that same refuge are also a resource of concern under terms of the 

respective endangered species acts (620 FW 1.4G). 

Negative features of the landscape, such as invasive plants, may demand a large part of the refuge 

management effort but are not designated as resources of concern. 

To identify these resources, the team reviewed numerous plans and assessments that have been 

completed (see Section 1.7). A large list of species, species groups, and habitats were identified (see 

Appendix E, Biological Resources of Concern list). The list was then narrowed to a shorter list of 

priority ROCs. 

The main criteria for selection of the priority ROCs included the following requirements drawn from 

the document Identifying Refuge Resources of Concern and Management Priorities: A Handbook

(USFWS 2008a): 

 Reflective of the Refuge’s establishing purposes and the Refuge System mission 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-11 

 Species that may be used as an indicator of the health of one the main natural habitat types 

found at the Refuge 

 Recommended as a conservation priority in the Wildlife and Habitat Management Review 

(USFWS 2008a) 

 Federally or State listed, candidate for listing, or species of concern 

Other criteria that were used in section of the resources of concern included the following: 

 Species groups and/or refuge features of special management concern 

 Species contributing to the biological diversity, integrity and environmental health of the 

ecosystem 

 Species where it is feasible to estimate population size (needed for future monitoring and 

adaptive management) 

Early in the planning process, the planning team invited extended team members to assist in 

identifying priority species for the Refuge (see Appendix I for names of team members). A number 

of different species were recommended by the participants in this collaborative workshop. The list 

was refined to 21 priority species for the Refuge and consists of canvasback, sago pondweed, 

northern shoveler, tui chub, white pelican, eared grebe, redhead, ruddy duck, yellow-headed 

blackbird, greater sandhill crane, bobolink, cinnamon teal, willow flycatcher, yellow warbler, 

redband trout, snowy plover, gadwall, mallard, sage thrasher, loggerhead shrike, and sage sparrow. 

Each species in discussed in more detail by habitat below. 

4.2.2 Relationship of Priority Resources of Concern to Habitat Goals and 

Objectives 

Wildlife habitat goals and objectives were designed directly around the habitat requirements of the 

priority ROCs. Goals were written for priority ROC habitats. Objectives were developed from the 

habitat requirements of priority ROC species. 

To develop objectives, the team followed the process outlined in the document Identifying Resources 

of Concern and Management Priorities for a Refuge: A Handbook (USFWS 2008a). For each 

priority ROC, the team identified the ecological attributes of habitats that are necessary to meet the 

ROC’s life history requirements, and are therefore, critical to sustain the long-term viability of the 

ROC and other benefitting species. Ecological attributes of habitats include parameters such as 

vegetation structure, species composition, age class or seral stage, patch size and/or contiguity with 

other habitats, hydrologic regime, absence of human disturbance, and natural disturbance events 

(e.g., flooding, fire). These attributes, when described in measurable terms, provide specific habitat 

targets that strongly correlate with the ability of a habitat to support priority species, and by 

extension, other benefitting species. For most attributes, the team developed “desired” conditions that 

were based partly on scientific literature review and partly on the team’s professional judgment. 

These desired conditions for specific attributes were used to help design measurable habitat-based 

objectives, as presented in Chapter 2. 

Limiting factors were also considered in developing objectives. A limiting factor is a threat to, or an 

impairment or degradation of, the natural processes responsible for creating and maintaining plant 

and animal communities. In developing objectives and strategies, the team gave priority to mitigating 

or abating limiting factors that presented high risk to ROCs. In many cases, limiting factors occur on 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-12 Chapter 4. Biological Environment 

a regional or landscape scale and are beyond the control of the individual refuge. Therefore, 

objectives and strategies may seek to mimic, rather that restore, natural processes. For example, 

mowing and/or grazing may be used to maintain a desirable vegetation structure, when restoring 

native grassland communities may be impractical. 

4.3 Major Habitat Types on Malheur Refuge 

4.3.1 Lacustrine (lakes) 

Overview 

Malheur Lake: One of the largest inland marshes in the United States, Malheur Lake may vary 

dramatically in size (from 500 to 110,000 acres) but generally fluctuates about 2 feet during the 

calendar year and upon average covers approximately 37,500 acres, or 20 percent of the total refuge 

acreage. On the basis of water depth, water chemistry, and vegetation, it is classified as an Inland 

Deep Fresh Marsh (Shaw and Fredine 1956). The lake is described in great detail in Duebbert (1969). 

It receives water from the Blitzen and Silvies rivers, fills from the center, then flows east and finally 

to the west, and then connects with Mud Lake. Water supply is predominantly influenced by 

snowpack on Steens Mountain to the south and the Blue Mountains to the north. 

The western section of Malheur Lake is a series of natural ponds separated by a network of low dune 

islands and peninsulas. The center section, the deepest area of the lake, is predominantly open water 

with some hardstem bulrush stands near the mouth of tributaries. The eastern section tends to be 

more alkaline and lacks tall emergent vegetation. 

Common emergent species in Malheur Lake include hardstem bulrush, cattail, burreed, Baltic rush, 

and various sedges. The largest stands of hardstem bulrush are at the mouths of both rivers and 

typically support mixed colonies of ibises, egrets, Franklin’s gulls, and western grebes. The lake 

contains extensive areas of open, aquatic bed habitat supporting submergent plants such as sago 

pondweed, water milfoil, horned pondweed, coontail, small and leafy pondweed, white water 

buttercup, bladderwort, and widgeon grass. 

Harney and Mud Lakes: Harney Lake has a bottom elevation about 8 feet lower than Malheur Lake 

and is deeper than Malheur Lake when it is full. However, Harney Lake dries up completely during 

dry periods, shifting from a hypersaline lake to a dry salt flat (Dugas 1996). Water often enters 

Harney Lake through Silver Creek. Harney Lake is too saline to support emergent vegetation. 

Regional Distribution, Condition, and Trends of this Habitat Type 

These types of aquatic systems are thinly scattered throughout the Great Basin. 

The large invasive carp population in Malheur and Mud lakes and in the Blitzen and Silvies rivers 

has severely compromised submerged aquatic vegetation (e.g., sago pondweed); therefore, the lakes 

do not adequately support refuge purposes. Historically, Malheur Lake was a key staging area for 

canvasbacks and tundra swans in the Pacific Flyway. As a consequence of declining habitat quality, 

these and other waterfowl no longer stage in significant numbers on the lake except during years 

following major carp control efforts. Waterfowl production is less than 10 percent of its potential on 

the lake because of carp. There were high numbers of canvasbacks using Malheur Lake during the 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-13 

falls of 1993 and 1994, after drought conditions and a carp control project in 1992; duck production 

was estimated to be over 100,000 produced per year on Malheur Lake before the carp invasion 

(Cornely 1982). During the 1980s, high water levels eliminated most emergent vegetation in Malheur 

Lake, causing a significant number of colonial birds to abandon nesting on Malheur Lake and shift to 

flooded private lands to the north. The large stands of hardstem bulrush that were present before the 

1980s flood have not recovered. Historically, Mud Lake had an extensive bulrush community used 

by nesting canvasbacks; however, with low water levels there are minimal bulrush stands present on 

the lake. 

Malheur Lake also supports a diverse community of other exotic fish species, and they likely have an 

adverse effect on the native species in the system. Other invasive aquatic species, such as quagga and 

zebra mussels, are not present but could arrive in the lake system in the future, with huge potential 

for negative effects on the natural biological integrity of the lakes and adjacent wetlands. 

When Harney Lake is full and less saline, it supports extensive stands of wigeongrass and high 

numbers of waterfowl. At higher salinities, it supports an abundance of brine shrimp and brine flies, 

important food sources for many birds. 

Key Species Supported 

The primary wildlife value of the refuge lakes includes their importance as foraging sites for 

migrating waterfowl, waterbirds, and shorebirds and as nesting habitat for colonial nesting waterbirds 

and diving ducks. Canvasbacks and tundra swans are particularly abundant when sago pondweed is 

abundant in the lakes, and many other dabbling and diving ducks are also supported in large 

numbers. Very high numbers of nesting colonial birds use the lake when habitat conditions are 

favorable, including white-faced ibis; American white pelican; great and snowy egrets; herons; 

Franklin’s, California, and ring-billed gulls; Caspian and Forster’s terns; and western, Clark’s, and 

eared grebes. Total colonial waterbird nests have at times exceeded 10,000 when the lakes reach 

optimal conditions. Migrant shorebirds use the lakes extensively, when natural fluctuating water 

cycles expose mudflats. The lakes are also very important to molting geese and ducks as the 

expansive open water provides them security from predators. Malheur Lake supports over 10,000 

molting ducks in good years, and some of the mallards molting there have been documented as birds 

that nested in California. Occasionally, when Harney Lake is full, it supports well over 300,000 

migrating ducks foraging on extensive beds of wigeongrass. 

The emergent vegetation in the lakes also once supported most of the Refuge’s population of 

muskrats and also supported many beaver and mink. 

The lakes are very important in preserving the life-history diversity of redband trout in the Harney 

Basin. A portion of the population migrates to the lower Blitzen River and also Malheur Lake during 

high water years. Migrations expand resources available to redband trout and allow expression of 

diverse life histories (Anderson 2009). Native tui chubs are also abundant in the lakes when water 

conditions are favorable, and they too are likely limited by other exotic fishes in the system. 

Historically, large numbers of native suckers were reported spawning in Sodhouse Spring (Bendire 

1875-1876) and they were likely once abundant in the lakes. Priority ROCs for this habitat type are 

presented in Table 4-1 and include canvasback, northern shoveler, tui chub, and American white 

pelicans. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-14 Chapter 4. Biological Environment 

Table 4-1. Selected Priority Resources of Concern Lacustrine Habitats 

Focal Species Habitat Structure and Attributes Life History 

Requirements 

Other Benefiting Species 

Canvasback Concentrate in large numbers in 

lakes and open marshes heavily 

vegetated with beds of sago 

pondweed (Mowbray 2002). 

Nesting requirements similar to 

redheads. 

Migration and 

breeding 

Tundra swan, geese, ducks, 

coots, grebes, fish, muskrat 

Northern 

shoveler 

Prefer margins of open shallow 

wetlands usually with submergent 

vegetation and associated nearby 

grasslands, sagebrush, or 

rangelands for nesting. Prefer grass 

cover for nesting from 0 to 2 feet 

(0.6 m) in height, 295 feet (>90 m) 

from water (Dubowy 1996). 

Breeding and 

foraging 

Teal, shorebirds, herons, 

egrets, other wading birds, 

blackbirds 

Tui chub Inhabit small streams to lakes, 

prefers areas of shallow water with 

heavy vegetation for spawning, 3 

feet (1 m). Diet of invertebrates, 

plant material, algae, plankton 

(Bird 1975; Knopf and Kennedy 

1981). 

Spawning and 

foraging 

Redband trout, cormorant, 

marsh and wading birds, 

mergansers, other native 

fish species 

White pelican Inhabit marshes and open water 

areas such as lakes and nesting on 

isolated, flat, low-lying islands 

with sparse interspersed vegetation 

adjacent to bare soil (Evans and 

Knopf 1993). Foraging in shallow 

water ≤37 feet (11.4 m) and prey 

dominated by small to medium 

sizes 1-27 inches (2.5-68.6 cm) 

(Finholt and Anderson 1995; 

McMahon and Evans 1991). 

Breeding and 

foraging 

Geese, ducks, herons, 

egrets, rails, white-faced 

ibis, coot, shorebirds, 

yellow-headed and other 

blackbirds, marsh wren, 

common yellowthroat, 

black tern, muskrat, mink 

Refuge Management Activities 

There is little direct management of the lakes. The primary management activity on Malheur Lake 

has been periodic carp control using rotenone when lake levels were low. A riprap barrier with 

screened culverts has been installed at the Narrows Bridge on Highway 205 to slow carp movements 

between Malheur and Mud lakes. In the 1950s dikes were constructed between dunes in the Cole 

Island Dike area to span the lake north to south, while other smaller dikes were constructed to keep 

water out of private lands north of the lake, but these dikes were destroyed during the flood of the 

1980s and are no longer functional. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-15 

4.3.2 Riverine 

Overview 

The major areas of riverine habitat on the Refuge are the Blitzen River and its tributaries. Ideal 

riverine conditions exist when hydrologic floodplains are intact and when waterways support riparian 

communities that provide shade to maintain cooler water temperatures and are appropriate to stream 

channel type. A fully functional river or stream exhibits balanced pool-riffle-glide ratios depending 

on slope and substrate due to the lack of fine sediments covering large section of river reaches. In 

such a waterway, water turbidity is typically low with an appropriate level of sediment storage, 

which buffers against the sediment loading of critical rearing pools and spawning gravels for native 

fishes. Boulders, undercut banks, logs, and vegetation provide ample hiding cover for native fishes 

and other aquatic species. Eddies and other slow-current areas contain abundant populations of 

various aquatic invertebrates. Low turbidity also allows a variety of native aquatic vegetation to 

establish and propagate in suitable microniches. 

On the Refuge, the highest quality riverine habitat occurs at the south end of the Refuge in the 

unchannelized reaches of the Blitzen River and in the major tributary streams (Mud, Bridge, and 

Krumbo creeks). Although artificial, the East Canal from Page Dam to Bridge Creek provides 

attributes of riverine habitat and is in better condition than much of the Blitzen system. Below the 

confluence of Bridge Creek, the river channel is deeply incised and does not support floodplain 

hydrology or riparian vegetation and is poor quality habitat for native fish. The river suffers from 

poor water quality with high sediment and nutrient loading and, in summer, warm temperatures (see 

Chapter 3). 

Silver Creek in the Double-O Unit is disconnected above the Refuge by Moon Reservoir dam and no 

longer has a natural channel until it reaches the boundary between the East Freeman and Martha 

Lake fields where the channel is re-established. Riverine habitat conditions are very poor, as flows 

are intermittent and the lower channel is artificially maintained by the diversion of spring water. 

Regional Distribution, Condition, and Trends 

A portion of lower Bridge Creek and 17.5 miles of the Blitzen River were channelized early in the 

20th century prior to refuge acquisition, resulting in degraded riverine conditions through much of 

this portion of the Blitzen Valley. In some reaches, channel incision has lowered water tables enough 

to allow sagebrush to grow along the river. Development of the irrigation system, including six active 

irrigation dams, further modified riverine hydrology and caused significant reduction of riverine 

habitats as floodplain connectivity was disrupted and natural riverine function was reduced. 

Much of the degradation of refuge water quality may be the result of historic overgrazing by 

livestock and the condition of upstream rangelands. It appears these factors still contribute to silt 

loading and high stream temperatures due to the slow recovery of riparian habitat in affected areas. 

Since restrictions on livestock grazing were implemented in the 1970s, riparian habitat associated 

with the riverine system has recovered in the south Blitzen Valley, but remains poor elsewhere. 

Channelization and overgrazing have increased incision of the Blitzen River, compromised in-stream 

habitat diversity, and diminished the system’s ability to disperse energy during high flow events. 

Channelization has also led to the loss of the functionality of most floodplains on the Refuge, and the 

associated channel incisions have reduced adjacent water tables and limited recovery of riparian 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-16 Chapter 4. Biological Environment 

vegetation. The presence of invasive carp likely has a significant impact in reducing the carrying 

capacity of the riverine system for native species. Altered hydrology and passage impediments have 

also influenced water and habitat conditions and access by redband trout. 

Key Species Supported 

Riverine habitats are prime habitat for redband trout, other native fishes, and native mollusks. This 

habitat is also important to Oregon spotted frogs, mergansers, belted kingfishers, river otters, and 

mink. Redband trout is the sole priority ROC species under this habitat type, and more information 

about this species is listed below in Table 4-2. 

Table 4-2. Riverine Habitat Priority Resources of Concern Species 

Focal 

Species 

Habitat Structure and 

Attributes 

Life History 

Requirements 

Other Benefiting Species 

Redband 

trout 

Native fish habitat for redband 

trout: stream shading (>80%), 

bank cover (no bare soil), bank 

stability (<5% eroding), channel 

stability (<1% channel 

movement), fine sediment <2 

mm (<10%), cover (>50% of 

channel (Zoellick and Cade 

2006); percent late summer 

pools (25%-75%), mean annual 

base flow (>45% of annual flow) 

(Raleigh et al. 1984). 

Year-round Native suckers, sculpins, 

dace, whitefish, mollusks, 

river otter, beaver 

Refuge Management Activities 

Within the past two decades, the refuge staff has focused on improving fish passage through refuge 

dams and screening irrigation diversions to minimize loss of fish via irrigation diversion. 

Considerable effort has been applied to enhance stream-side riparian habitat in Bridge and Mud 

creeks and along the southern reach of the Blitzen River through plantings. Inverted weirs were 

installed in this reach of the river to raise the water table and increase habitat diversity in the natural 

channel. These projects are still being monitored to assess their effectiveness. 

4.3.3 Woody Riparian 

Overview 

The Refuge hosts a variety of riparian habitat along the Blitzen River and its tributaries, along ditches 

and canals, along remnant traces of previously active sloughs in the Blitzen Valley, and in a few 

patches in the Double-O Unit. Riparian habitat encompasses 800 to 1,000 acres. Although many 

plant associations are found within this habitat type, the principal woody species include willows, 

cottonwoods, alder, redosier dogwood, Wood’s rose, golden currant, common snowberry, Lewis’ 

mock orange, water birch, and alder. Herbaceous groundcover is characterized by Nebraska sedge, 

yellow monkey-flower, Northwest cinquefoil, American speedwell, wooly sedge, slender-beaked 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-17 

sedge, meadow barley, tufted hairgrass, western yarrow, and Baltic rush. The south Blitzen Valley 

also supports extensive stands of willow associated with irrigated meadows, and these stands are very 

important for riparian landbirds. Smaller stands of willow are associated with wet meadows and 

seasonal wetlands in the north Blitzen Valley and the Double-O. 

Regional Distribution, Condition, and Trends 

Since major reductions in livestock grazing occurred during the 1970s, riparian habitats have 

increased and expanded, especially in the south Blitzen Valley. The condition of riparian habitat is 

generally good. There is much diversity in the plant communities along the Blitzen River, its 

tributaries, and the East Canal. In other portions of the Refuge, diverting water for irrigation or 

incision of stream banks has lowered the water table, and this has prevented riparian species from reestablishing. 

Threats to riparian habitat on the Refuge include invasion by non-native plants, such as reed 

canarygrass, water hemlock, Russian olive, and perennial pepperweed; river channelization; lowered 

groundwater table; and water quality impairments. Grazing by trespassing livestock occasionally 

occurs and can be damaging to the structure of riparian habitat. 

Key Species Supported 

There are 97 native landbird species considered by the Partners in Flight plan to be associated with 

riparian habitat in the Columbia Plateau (Altman & Holmes 2000). This plan lists several species as 

“dependent,” including western wood peewee, Bullock’s oriole, willow flycatcher, yellow-breasted 

chat, yellow-billed cuckoo, and yellow warbler. The same species, including lazuli bunting and 

excluding western wood peewee, are considered focal species under the plan. 

Common refuge breeding bird species using this habitat include song sparrow, willow flycatcher 

yellow warbler, American robin, eastern kingbird, and black-billed magpie. Also present, but less 

common, are long-eared owl, black-headed grosbeak, yellow-breasted chat, cedar waxwing, and 

lazuli bunting. Many other warblers, vireos, and sparrows use this habitat type during migration. 

Riparian areas are very important to beaver, porcupine, and mule deer (especially in winter) and are 

used as cover by raccoons, striped skunks, and weasels. Montane voles and jumping mice are also 

closely associated with this habitat. The priority ROC species under this habitat type include willow 

flycatcher and yellow warbler and more information about these species is listed below in Table 4-3. 

Table 4-3. Woody Riparian Priority Resources of Concern Species 

Focal Species Habitat Structure and 

Attributes 

Life History 

Requirements 

Other Benefiting Species 

Willow 

flycatcher 

Inhabit thickets of willow, 

cottonwood, dogwood, 

and other shrubs along 

river corridors or 

waterways through the 

broad valley. Shrub layer 

cover >40%-80% of 

native shrubs more than 3 

feet (1 m) tall; canopy tree 

Breeding and 

foraging 

Yellow-billed cuckoo, black-headed 

grosbeak, long-eared owl, yellowbreasted chat, song sparrow, eastern 

kingbird, skunk, weasel 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-18 Chapter 4. Biological Environment 

Focal Species Habitat Structure and 

Attributes 

Life History 

Requirements 

Other Benefiting Species 

cover <30% (Altman and 

Holmes 2000; Sedgwick 

2000). 

Yellow 

warbler 

Found in riparian and wet 

deciduous thickets 

dominated by willow, 

alder, dogwood, and other 

early successional species. 

Mean territory 0.14-0.29 

ha, nest height of 1.6-6.5 

feet (0.5-2.0 m) located in 

dense stands (Knopf and 

Sedgwick 1992; Lowther 

et al. 1999). 

Breeding and 

foraging 

Yellow-billed cuckoo, black-headed 

grosbeak, long-eared owl, yellowbreasted chat, song sparrow, eastern 

kingbird, skunk, weasel 

Refuge Management Activities 

Historically, willows, other shrubs, and trees were mechanically and chemically removed to 

maximize wet meadow forage for livestock. This practice ended in 1972, and grazing and haying 

activities were also excluded from stream banks to protect riparian habitat. A 400-foot ungrazed 

corridor along the Blitzen River and a 200-foot corridor for other streams were established as a 

standard in the Blitzen Valley Management Plan (USFWS 1990). Selective burning, grazing, haying, 

or mechanical disturbance may be used to reinvigorate decadent riparian stands. Many riparian areas 

have been excluded from livestock grazing by implementing hay-only management practices or 

through the use of protective fencing. 

Refuge riparian habitat has been managed for structure, patch size, and patch distribution or spacing 

of woody clumps within a specified area to meet life-history needs of migratory landbirds, including 

willow flycatchers and yellow warblers (USFWS 1990). 

4.3.4 Palustrine Emergent (Seasonally flooded wet meadows) 

Overview 

Meadows are influenced by water depths and the timing of irrigation. On the Refuge, they are 

seasonally flooded and managed artificially by irrigation. The largest areas of meadow habitats are 

located in the southern Blitzen Valley, where much of the valley is flat and water supplies are more 

dependable. Meadows in the northern half of the Blitzen Valley and in the Double-O Unit tend to be 

drier and less extensive; however, they are widely dispersed throughout these managed units of the 

Refuge. The Blitzen Valley and Double-O currently supports approximately 20,000 to 25,000 acres 

of meadow habitats. Water conditions in meadows range from subirrigated up to 1 foot in depth. 

Drier sites are typically dominated by creeping wildrye or saltgrass, while wetter areas tend to be 

dominated by sedges such as woolly sedge, Nebraska sedge, and slender-beaked sedge. Other native 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-19 

species include Baltic rush, arrow-grass, Nevada bluegrass, western yarrow, slender cinquefoil, 

large-leafed avens, and fringed willow-herb.

Regional Distribution, Condition, and Trends 

Beginning in the 1870s, uplands, marshes, and irrigated meadows in the Blitzen Valley and DoubleO were converted to wet meadows to provide forage for livestock. Further development of the 

irrigation system in the Blitzen Valley by the CCC led to further habitat conversions in the 1940s. 

Acreage numbers for meadow habitats have remained relatively stable since these earlier 

conversions. 

The largest threats to the biological integrity of meadows are invasive plant species. Reed 

canarygrass poses the greatest threat and has already degraded extensive areas of meadow habitat in 

the Blitzen Valley. Reed canarygrass stands are very poor wildlife habitat. Limited water supplies are 

another threat to maintenance of meadows. If water supplies are reduced by global warming in the 

future, the Refuge will need to be strategic about how it uses and delivers water to important meadow 

habitat. 

Key Species Supported 

The primary importance of meadows is to provide nesting cover for ground-nesting birds. Cover 

provided by drier meadow sites serves nesting cinnamon teal, northern shovelers and northern pintail. 

Short vegetation in meadows provides habitat for nesting bobolinks and shorebirds, such as Wilson’s 

snipe, Wilson’s phalarope, American avocets, and black-necked stilts. Other nesting species are 

numerous (e.g., mallard, gadwall, short-eared owl, western meadowlark, long-billed curlew). 

Meadows also serve as foraging sites for territorial greater sandhill cranes, Canada geese, waterfowl, 

white-faced ibises, and other waterbirds. Meadows support large numbers of montane voles and other 

small mammals, which are important prey for raptors and mammalian predators (e.g., weasels and 

coyotes). Deer, pronghorn, and occasionally elk graze in refuge meadow habitats. Priority ROC 

species for this habitat type are listed below in Table 4-4. 

Table 4-4. Palustrine Emergent (seasonally flooded wet meadow) Priority Resources of 

Concern Species 

Focal 

Species 

Habitat Type Habitat Structure and 

Attributes 

Life History 

Requirements 

Other 

Benefiting 

Species 

Cinnamon 

teal 

Palustrine 

emergent 

(seasonally 

flooded wet 

meadow) 

Use seasonal and semipermanent 

freshwater marsh nesting near 

water in low dense perennial 

vegetation composed of rushes, 

grasses, and various forbs 

interspersed with willows, 

rabbitbrush, and greasewood. 

Emergent layer cover with a 

height of 11-35 inches (28-90 

cm); grass layer cover with a 

height of <4 inches (10 cm); 

water depth 5.5-58.5 cm) 

Breeding and 

foraging 

Mallard, northern 

harrier, northern 

shoveler, 

northern pintail, 

short-eared owl 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-20 Chapter 4. Biological Environment 

Focal 

Species 

Habitat Type Habitat Structure and 

Attributes 

Life History 

Requirements 

Other 

Benefiting 

Species 

(Thorne and Zwauk 1993). 

Greater 

sandhill 

crane 

Palustrine 

emergent, 

(seasonally 

flooded marsh 

associated 

with wet 

meadow) 

Found in isolated, open, wet 

marshy meadows dominated by 

grasses, sedges, and rushes 

surrounded by shrubs. 

Shrub/emergent cover <30%; 

grass cover layer 40%-50%; forb 

cover layer 10%-20% (Mullins 

and Bizeau 1978; Stone 2009). 

Breeding and 

foraging 

Shrike, teals, 

gadwall, 

meadowlark, 

common 

yellowthroat, 

Savannah 

sparrow, 

blackbirds, voles, 

mice, nesting 

shorebirds 

Bobolink Palustrine 

emergent, 

(seasonally 

flooded marsh 

associated 

with wet 

meadow) 

Breed in subirrigated meadow 

composed of grasses and large 

forbs. Dependent on annual 

growth of grass cover layer 50%-

70%, up to 3 feet (1 m) tall; 

10%-20% forbs; bare ground 

<20% (Dechant et al. 1999; 

Moskwik and O’Connell 2006; 

Wittenberger 1978). 

Breeding and 

foraging 

Shrike, teals, 

gadwall, 

meadowlark, 

common 

yellowthroat, 

Savannah 

sparrow, 

blackbirds, voles, 

mice, nesting 

shorebirds 

Refuge Management Activities 

During spring irrigation, wet meadows are sheet flooded (subirrigated to 5 inches of standing water). 

To provide habitat for breeding greater sandhill cranes, Canada geese, and early nesting mallards, 

irrigation will commence by March 15 for a majority of wet meadow habitat. Fall irrigation of some 

meadow areas may be desirable to achieve other habitat goals. Irrigation water is maintained in 

meadows through early August for crane broods, except when drawdowns are necessary to repair 

facilities or accomplish other habitat management projects (e.g., mowing). 

Meadows are managed to provide two habitat structure objectives: to provide dense nesting cover for 

ground-nesting birds, and to provide short stubble for early green-up as forage for early nesting birds 

such as waterfowl and cranes and as short-cover nesting sites for shorebirds. To achieve the second 

objective, meadows are treated by mowing the vegetation in late summer and removing it as hay or 

through rake-bunch grazing. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-21 

4.3.5 Palustrine Emergent (seasonally flooded marsh associated with wet 

meadows) 

Overview 

This habitat type, measuring approximately 17,000 to 18,000 acres, exists within a mosaic of wet 

meadow and open water areas. Emergent marshes are found throughout the southern Blitzen Valley, 

become less extensive north of Buena Vista, and occur in the southern half of the Double-O Unit. 

Common emergent plant species include burreed, bulrushes, cattails, sedges, rushes, and spike 

rushes. Refuge emergent marshes are dominated by hardstem bulrush, cattails, or broad-fruited 

burreed. These emergents typically tolerate fluctuations in water availability ranging from 3 feet (1 

m) above to 4-5 inches (10-12 cm) below the soil surface. Submergent plants such as pondweeds, 

bladderworts, waterweeds, and duckweeds occur in adjacent deeper open water (aquatic beds) areas. 

Willow species can occur along elevated ecotones along marsh perimeters. 

Regional Distribution, Condition, and Trends 

The greatest challenge associated with this habitat is maintaining an adequate prescribed fire cycle to 

remove excess litter, create open water areas, and generally make it more conducive to use by 

wildlife (e.g., nesting cranes and mallards). The two prevalent invasive species within emergent 

marshes are common reed and hybrid cattail. Some emergent stands in the Blitzen Valley (i.e., 

common cattail) have expanded and encroached into adjacent wet meadow and open water areas in 

the past decade, reducing habitat values for some nesting birds. 

Common reed and hybrid cattails have the potential to displace significant areas of marsh plant 

community types that are more valuable for nesting birds. 

Key Species Supported 

Wildlife species associated with these marsh habitats include sandhill cranes, trumpeter swans, 

overwater nesting ducks (diving ducks and mallards), rails, bitterns, black and Forster’s terns, coots, 

marsh wrens, common yellowthroats, and yellow-headed and red-winged blackbirds. Marshes 

provide foraging, resting, pairing, and nesting habitat for these species. Emergent vegetation in 

marshes provides escape cover for broods of numerous species, particularly late-season nesters such 

as gadwall, redhead, and grebes. The priority ROC species under this habitat type are listed below in 

Table 4-5 and include yellow-headed blackbirds and greater sandhill cranes. 

Table 4-5. Palustrine Emergent (seasonally flooded marsh associated with wet meadow) 

Priority Resources of Concern Species 

Focal Species Habitat Structure and Attributes Life History 

Requirements 

Other Benefiting 

Species 

Yellowheaded 

blackbird 

Found in a variety of wetland areas 

but in this region prefers seasonal 

wetland with dense emergent 

vegetation over standing water. 

Favor vegetation around 23 inches 

(60 cm) in height, a mean stem 

density of 80-104/yd2, over 11-22 

Breeding and 

foraging 

Bitterns, mallards, 

other waterfowl, sora, 

other rails and marsh 

birds, other blackbirds, 

willets, snipe, other 

shorebirds, swallows 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-22 Chapter 4. Biological Environment 

Focal Species Habitat Structure and Attributes Life History 

Requirements 

Other Benefiting 

Species 

inches (28-57 cm) of water (Twedt 

and Crawford 1995). 

Greater 

sandhill crane 

Prefer coarse, emergent vegetation 

predominately hardstem bulrush, 

cattail, and burreed with an average 

water depth of 7 inches (18.0 cm) 

(Littlefield 1995; Tacha et al. 1992) 

for nesting. 

Nesting Bitterns, mallards, 

other waterfowl, sora, 

other rails and marsh 

birds, other blackbirds, 

willets, snipe, other 

shorebirds, swallows 

Refuge Management Activities 

The maintenance of existing emergent communities is artificial, requiring extensive infrastructure 

and active water diversion. Tools such as burning, mowing, disking, and using herbicides have been 

used to enhance this habitat type. Herbicides are occasionally used to control invasive species within 

this community. 

4.3.6 Palustrine Open Water/Emergent (semipermanently flooded wetland 

impoundments) 

Overview 

This habitat type, measuring between 2,200 and 2,800 acres, is primarily provided in wetland 

impoundments in the Blitzen Valley and Double-O units. Palustrine open water habitats are semi 

permanently flooded at depths that preclude the development of extensive stands of emergent 

vegetation. Extensive areas of emergents occur in larger impoundments. The aquatic beds of these 

impoundments support submerged and floating plants including common and greater duckweed; 

Canadian waterweed; coontail; water milfoil; common bladderwort; white water crowfoot; and sago, 

longleaf, and small pondweeds. Emergent plants occupy shallow areas within and alongside of open 

water communities and include bulrushes, cattails, sedges, rushes, and spike rushes. 

Regional Distribution, Condition, and Trends 

Most refuge impoundments are in good condition and meet the goal of providing hemi-marsh 

conditions (approximately half marsh and half open water); however, a few are overgrown with 

emergent vegetation and lack diversity and extent of open water. These are typically sites that have 

poor water control or that have undergone changes in hydrology. 

Palustrine systems are threatened by a number of factors. Invasive species such as carp and reed 

canarygrass reduce their wildlife values. Aging infrastructure and management of vegetation within 

the water delivery system poses challenges in ensuring reliable and consistent water supplies.

Key Species Supported 

These impoundments are the primary habitat for breeding and foraging of the Refuge’s population of 

trumpeter swans. The impoundments provide brood water for late-nesting ducks, such as redheads 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-23 

and gadwalls, and provide overwater nesting substrate for a large variety of wetland birds, including 

Canada geese, diving ducks, mallards, American coots, rails, grebes, and colonial species such as 

white-faced ibises and Franklin’s gulls. They also provide foraging habitat for migrating waterfowl 

and serve as night roosts for staging sandhill cranes and Canada geese. They serve migrant 

shorebirds when they are being flooded or drawn down and provide very shallow or moist mudflats. 

Muskrats use the emergent marsh component of this habitat for their lodges. Their lodges are also 

used by mink, which hunt muskrats and wetland birds in the marshes. Raccoons also forage in these 

areas. 

The priority ROC species for this habitat type are listed in Table 4-6 and consist of eared grebes, 

redhead ducks, and ruddy ducks. 

Table 4-6. Palustrine Open Water/Emergent (semipermanently flooded wetland 

impoundments) Priority Resources of Concern Species 

Focal 

Species 

Habitat Structure and 

Attributes 

Life History 

Requirements 

Other Benefiting 

Species 

Eared grebe Inhabit large fresh open water 

marshes and prefer to nest in 

waters with abundant and diverse 

submergent aquatic beds and 

periphery emergent vegetation 

and 10 feet (3 m) deep. 60:40 to 

70:30 ratio of open water to 

emergent vegetation with a stem 

density 8-144 stems/yd2, open 

water areas with submergent 

vegetation covering 40%-70% of 

area dominated by sago pondweed 

(Cullen et al. 1999; Dechant et al. 

2002). 

Breeding and 

foraging 

Swans, geese, ducks, 

herons, egrets, rails, ibis, 

coot, yellow-headed and 

other blackbirds, swamp 

sparrow, marsh wren, 

common yellowthroat, 

black tern, muskrat, mink 

Redhead Inhabit permanently or 

semipermanent palustrine 

wetlands, water depth 8-39 inches 

(20-100 cm) (interspersed open 

water pockets 1.7-2.5/yd2; 

emergent stem density bulrush 

350-450 stems/yd2 or cattails 32-

52 stems/yd2 (Custer 1993; Low 

1945; Woodin and Michot 2002). 

Brooding White pelican, egrets, 

herons, mergansers, 

grebes, cormorants, rails, 

ducks, coot, marsh wren, 

black tern, red-winged 

and yellow-headed 

blackbirds, muskrat 

Ruddy duck Inhabit large open water areas 

with submergent vegetation 

during foraging but use dense 

emergent vegetation >35 inches 

(91 cm) in height for breeding. 

Prefer stems density 88-200/yd2 

with a water depth of 16-24 

inches (42-61 cm) (Bura 2002). 

Breeding and 

foraging 

Swans, geese, ducks, 

herons, egrets, rails, ibis, 

coot, yellow-headed and 

other blackbirds, swamp 

sparrow, marsh wren, 

common yellowthroat, 

black tern, muskrat, mink 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-24 Chapter 4. Biological Environment 

Refuge Management Activities 

With the exception of small natural depressions next to springs (e.g., Double-O Spring), the 

palustrine community has been maintained through active and intensive management. Emergents 

within impoundments are managed to maintain a hemi-marsh condition. Tools such as burning, 

mowing, disking, and using herbicides have been used to reduce extensive stands of emergents. 

Occasional drawdowns oxidize nutrients and consolidate substrates to facilitate the germination of 

submergent vegetation, such as sago pondweed. When pond bottoms are exposed production of 

smartweed and other desirable native colonizers is higher after reflooding, especially in mudflats in 

shallow benches. Periodic drawdowns are occasionally used to remove carp from impoundments. 

When impoundments cannot be totally dried up, rotenone, netting, and electroshocking have been 

used to remove invasive carp. 

4.3.7 Dry Meadow 

Overview 

Dry meadows are influenced by water depths and the timing of irrigation through the availability of 

subirrigation. Standing water is typically not found within these plant communities. The largest areas 

of dry meadow habitats are located in the northern Double-O and scattered throughout the Blitzen 

Valley where gradual shifts in elevation facilitate the presence of this habitat type, which lies 

between wet meadows and sagebrush lowland/salt desert scrub. The Blitzen Valley and Double-O 

currently supports approximately 4,500 to 5,500 acres of dry meadow habitats. Dry meadow habitats 

are typically subirrigated but may be temporarily inundated during flood events. Shallow depth to 

water table makes these areas largely uninhabitable by woody upland vegetation such as basin big 

sagebrush and greasewood. Sites are typically dominated by creeping wildrye, Nevada bluegrass, 

bluejoint, or saltgrass. Other native species include western yarrow, slender cinquefoil, and lanceleaf 

goldenweed.

Regional Distribution, Condition, and Trends 

Depth to water table is a driving factor influencing the presence of dry meadow communities. Water 

management within wet meadows and emergent marshes impact outlying water tables, and these 

impacts cause this habitat type to either expand or contract. In areas near prevailing ecotones 

between dry meadows and sagebrush lowland/salt desert scrub habitats, upland shrub invasion has 

occurred. This habitat is highly susceptible to invasion by perennial pepperweed. 

The largest threat to the biological integrity of dry meadows is invasive plants (either upland shrubs 

or noxious weeds). Fire suppression over the last century has favored the expansion of shrub 

communities into this habitat, and the prolific availability of weed seed throughout the Refuge proves 

difficult to manage. 

Key Species Supported 

The primary importance of dry meadows is to provide nesting cover for ground nesting birds such as 

cinnamon teal, bobolink, gadwall, and mallard. These communities are also significant for the 

western meadowlark, a species that uses this habitat type for breeding and foraging. The latter 

species is the priority ROC species for this habitat type and more information about it is listed in 

Table 4-7. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-25 

Table 4-7. Dry Meadow Priority Resources of Concern Species 

Focal 

Species 

Habitat Structure and Attributes Life History 

Requirements 

Other Benefiting 

Species 

Western 

meadowlark 

Prefer open country with meadows 

and fields with good grass and litter 

cover and little or no woody layer. 

Grass layer 20%-80%, forb layer 

1%-17%, mean thatch layer of 16%, 

bare ground ≤10% (Dechant et al. 

2002; Greer 2009; Lanyon 1994) 

Breeding and 

foraging 

Savannah sparrow, 

vesper sparrow, horned 

lark, blackbirds, sandhill 

crane, northern harrier, 

curlew 

Refuge Management Activities 

Active management within dry meadows consists mainly of weed control and the stimulation of 

nesting cover via occasional disturbance (prescribed fire, haying, rake-bunch grazing). Water 

management of adjacent habitats does influence these plant communities by raising or lowering the 

prevailing water table. 

4.3.8 Salt Desert Scrub 

Overview 

Salt desert scrub occurs in barren alkali flats or alkaline valley bottomlands, and occupies 40,000 

acres of the Refuge. This community is most abundant in alkaline areas around the Double-O Unit, 

Harney Lake, and Mud Lake but also occurs in portions of the Blitzen Valley and along the east end 

of Malheur Lake where soil alkalinity is high. Infrequent inundation of outer playa areas or wind 

erosion from these playas distributes salts to nearby low-lying areas, causing elevations in alkalinity 

and pH, which favor this community association. The plant community for this habitat type consists 

of widely spaced shrubs with dense patches of rhizomatous grasses, as well as low densities of other 

annual and perennial grasses and succulent forbs. Dominant species are black greasewood and inland 

saltgrass, but shortspine horsebrush, fourwing saltbush, bud sage, green and gray rabbitbrush, alkali 

sacaton, alkali cordgrass, and alkali bluegrass are often present. Mat muhly and Sandberg’s bluegrass 

may be present in mosaics which exhibit more moderate conditions (lower pH.). 

Regional Distribution, Condition, and Trends 

These upland sites also experience moderate to heavy grazing by livestock during the winter, and this 

probably reduced the resiliency of this community to resist invasive plants. Perennial pepperweed 

has significantly encroached in these areas at lower elevations and has replaced vast areas of native 

vegetation. Rabbitbrush tends to be invasive in some sites after burning. 

Livestock grazing may compromise plant species diversity within this community type. There is no 

wildlife benefit to grazing in these uplands. Perennial pepperweed has invaded vast areas of this 

habitat in the Blitzen Valley and to a lesser degree in the Double-O Unit. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-26 Chapter 4. Biological Environment 

Key Species Supported 

This community is preferred for nesting by loggerhead shrikes, which use the thorny shrubs to 

impale their prey. Similar to the sagebrush lowland community this habitat is important as nesting 

cover for ground-nesting birds, such as mallards, gadwalls, and short-eared owls when in proximity 

to water. Nesting birds primarily rely on tall grass and forb components. A variety of landbirds also 

breed here, including sage thrashers, Brewer’s sparrows, black-throated sparrows, sage sparrows, 

Brewer’s blackbirds, and western meadowlarks. Many mammalian species use these communities 

including American badgers, weasels, black-tailed jackrabbits, cottontails, Townsend’s and northern 

pocket gophers, and deer mouse. They are typical denning sites for coyotes and are also frequented 

by bobcats. They also get used regularly by mule deer and pronghorn. The priority ROC species 

under this habitat type is loggerhead shrike, and more information about this species is listed below 

in Table 4-8. 

Table 4-8. Salt Desert Shrub Priority Resources of Concern Species 

Focal Species Habitat Structure and Attributes Life History 

Requirements 

Other Benefiting 

Species 

Loggerhead 

shrike 

Found in open gentle terrain with low 

density of shrubs (particularly sagebrush) 

mixed with low and sparse grasses such 

as saltgrass. Shrub layer cover 5%-15%, 

grass layer cover 50%-70% <10 inches 

(25 cm) tall (Pampush and Anthony 

1993; Paton and Dalton 1994). 

Breeding and 

foraging 

Sage sparrow, sage 

thrasher, vesper sparrow, 

snakes, shrews, lizards 

Refuge Management Activities 

Although this habitat type was historically intensively grazed, in more recent years cattle have been 

excluded from grazing in this habitat type on the Refuge. Prescribed burning is periodically used in 

these sites to set back succession and composition over the short term, but these communities often 

do not contain enough continuous fuels to accomplish a complete burn, so the result is a mosaic 

burning pattern. 

4.3.9 Sagebrush Lowland 

Overview 

These upland habitats occur in elevated basin bottomlands with deep silty or sandy soils along stream 

channels in valley bottoms and flats. Lowland sagebrush habitat is found on 4,300 to 4,500 acres of 

the Refuge. Structurally, these habitats are composed of widely spaced medium-tall to tall shrubs 

(1.5-6 feet) with an understory of perennial bunchgrasses. Basin big sagebrush, Wyoming big 

sagebrush, rabbitbrush, and basin wildrye are dominant features in this habitat type. These habitats 

occur in upland areas on the valley floors of the Blitzen Valley and Double-O units. The fire 

frequency in these habitats ranges from 10 to 25 years (ODFW 2006). 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-27 

Regional Distribution, Condition, and Trends 

Historically, this habitat was probably more abundant in the Blitzen Valley. As the development of 

the irrigation system changed the water regime, it likely also changed the composition of plant 

communities on lower-elevation upland sites. However, most of the loss of upland habitat due to 

development of irrigation more likely occurred in the meadow areas dominated by creeping 

wildrye/Nevada bluegrass communities throughout the Blitzen River Valley. These communities 

have developed along the incised river and stream channels and along the edges of some refuge 

canals and dikes. 

Before the reduction of grazing in the 1970s, these upland sites were moderately to heavily grazed by 

cattle during the winter, with cattle use extending into early spring, for over 30 years. This use 

degraded these sites and likely changed a number of plant community characteristics. 

Invasive plants, such as cheatgrass, have degraded this community and have altered the natural fire 

regime by allowing more frequent fire-return intervals. Perennial pepperweed has significantly 

encroached in these areas at lower elevations and has replaced vast areas of native vegetation. 

Rabbitbrush tends to proliferate in some sites after burning. 

Weed invasions are the biggest threats to this habitat type. There is no wildlife benefit to grazing in 

these uplands. Grazing by trespassing livestock can be an issue. 

Key Species Supported 

A primary value of this upland community is as dense nesting cover for ground-nesting birds, such as 

mallards, gadwalls, and short-eared owls. These birds primarily rely on tall grass and forb 

components. A variety of landbirds also breed here, including California quail (Callipepla 

californica), sage thrashers, Brewer’s sparrows, Brewer’s blackbirds, and western meadowlarks. 

Many mammalian species also use these communities, including American badgers, weasels, blacktailed jackrabbits, cottontails, potentially pygmy rabbits, Townsend’s and northern pocket gophers, 

least chipmunk, bushy-tailed and desert woodrats, northern grasshopper mouse, deer mouse, and 

sagebrush vole. These habitats are typical denning sites for coyotes and are also frequented by 

bobcats. They also get used by mule deer, pronghorn, and elk and provide good hiding cover for 

these species. The priority ROC species under this habitat type consist of gadwall and mallard. More 

information about these species is listed below in Table 4-9. 

Table 4-9. Sagebrush Lowland Priority Resources of Concern Species 

Focal 

Species 

Habitat Type Habitat Structure and 

Attributes 

Life History 

Requirements 

Other Benefiting 

Species 

Gadwall Sagebrush 

lowland 

Prefer islands of brushy 

habitat with Great Basin 

wildrye, or tall grass or forb 

component in proximity to 

open water. Shrub layer 

cover <10%; herbaceous 

veg. cover 10%-20%, 9-13 

inches (25-35 cm) tall, 

within 147 feet (45 m) of 

Nesting Short-eared owl, 

mallard, western 

meadowlark, sage 

thrasher 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-28 Chapter 4. Biological Environment 

Focal 

Species 

Habitat Type Habitat Structure and 

Attributes 

Life History 

Requirements 

Other Benefiting 

Species 

open water (Leschack et al. 

1997; Sousa 1985). 

Mallard Sagebrush 

lowland 

Nesting in dense cover 

scattered shrub lands 

surrounded by water for 

brooding (Drilling et al. 

2002). Nests are generally 

equal to or less than 164 

yards (150 m) from water 

(Dzus and Clark 1997). 

Early season 

nesting and brood 

water 

Short-eared owl, 

gadwall, song 

sparrows 

Refuge Management Activities 

The primary management activities in these upland communities are weed control and prescribed 

burning to reinvigorate basin wildrye for dense nesting cover for ducks. 

4.3.10 Sagebrush Steppe 

Overview 

This community includes 14,000 to 15,000 acres on the Refuge and is dominated by shrubs with an 

understory of various bunchgrass and forb species found within interspaces. It can be found above 

greasewood/lowland sagebrush communities on various aspects, slopes, and soil types. It occurs 

around the fringe of the Blitzen Valley at higher elevations, at several locations in the Double-O 

Unit, and along the south side of Harney Lake. Plant species include Wyoming and low sagebrush, 

bluebunch wheatgrass, Sandberg’s bluegrass, bottlebrush squirreltail, Idaho fescue, needle-andthread, Thurber’s needlegrass, western yarrow, arrowleaf balsamroot, and various locoweed and 

phlox species. A gradient in soil depth determines whether Wyoming big sagebrush or low sagebrush 

dominates a site. Low sagebrush sites typically host higher densities of forbs due to higher 

concentrations of available soil moisture due to shallow, rocky conditions. These communities 

depend on natural fire cycles or equivalent disturbance to maintain a balance between shrub, grass, 

and forb components. A lack of disturbance lends itself to high shrub densities with sparse vegetation 

in the interspaces. 

Regional Distribution, Condition, and Trends 

Originally, upland habitats were composed of native shrubs, bunchgrasses, and forbs. Most of the 

former native vegetation has been severely altered by historical land use, including intensive 

livestock grazing, reduced burning frequency, and cultivation. Large areas of shrub-steppe have been 

seeded to crested wheatgrass or as part of former “fire restoration” activities. 

Invasive plants, such as medusahead and cheatgrass, are major threats to the remaining shrub-steppe 

areas of the Refuge. Medusahead is capable of outcompeting native grasses and forbs in the 

understory. An altered fire regime resulting in more frequent fire return intervals due to the volatility 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-29 

of cheatgrass can limit recovery of sagebrush species in these communities, and wildfire can 

exacerbate these invasions. 

Key Species Supported 

Examples of obligate shrub-steppe species include sage-grouse, Brewer’s sparrow, sage sparrow, and 

sage thrasher. Likely because of the elevation, condition and fragmentation of refuge shrub-steppe, 

only very limited use by sage-grouse has been observed. Historically the area also supported sharptailed grouse (Tympanuchus phasianellus), which were last documented in southeastern Oregon in 

1940. Many other birds occur in shrub-steppe but are not as dependent on sagebrush. Examples of 

these include burrowing owl (Athene cunicularia), lark sparrow (Chondestes grammacus), vesper 

sparrow, horned lark, loggerhead shrike, long-billed curlew, and western meadowlark. 

Mule deer, pronghorn, and occasionally elk use these areas, which are within their winter range. 

Coyotes, bobcats, and badgers are common in these areas, and mountain lions are rarer, but present. 

The black-tailed jackrabbit, Nuttall’s cottontail, least chipmunk, Townsend’s and golden-mantled 

ground squirrels, and northern and Townsend’s pocket gophers are locally abundant in shrub step. 

A variety of reptiles use shrub-steppe habitat, including sagebrush, fence and side-blotched lizards; 

western rattlesnakes; racers; gopher snakes; and common garter snakes. Amphibians are represented 

by spade-foot toads. 

The priority ROC species for this habitat type is the sage thrasher, and more information about this 

species is listed below in Table 4-10. 

Table 4-10. Sagebrush Steppe Priority Resources of Concern Species 

Focal 

Species 

Habitat Structure and Attributes Life History 

Requirements 

Other Benefiting 

Species 

Sage 

thrasher 

Found in open terrain with a high density of 

sagebrush and large contiguous tracts. Shrub 

layer cover 5%-25%, 31 inches (>80 cm) in 

height; other shrub cover <10%; herbaceous 

cover 5%-20%; tract size >39 acres (16 ha) 

(Altman and Holmes 2000; Reynolds et al. 

1999). 

Breeding and 

foraging 

Sage sparrow, 

sage-grouse, longbilled curlew, 

ground squirrel, 

mule deer, 

pronghorn 

Refuge Management Activities 

To provide green winter browse for wintering Canada geese, crested wheatgrass seedings have been 

treated with livestock grazing to provide short stubble. Otherwise, cattle have been excluded from 

most of these sites on the Refuge. Research on restoring crested wheatgrass areas to more native 

shrub-steppe communities is being conducted in conjunction with the Eastern Oregon Agricultural 

Research Center (USDA Agricultural Research Service). 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-30 Chapter 4. Biological Environment 

4.3.11 Dune 

Overview 

Dune habitat on the Refuge is located adjacent to playa basins and is characterized by open sand 

ridges with widely spaced shrubs, grasses, and forbs. Created by wind erosion off nearby dry playa 

bottoms (i.e., Stinking and Harney lakes), dune shrub communities are made up of shortspine 

horsebrush, fourwing saltbush, bud sage, green and gray rabbitbrush, and black greasewood. Grasses 

include Indian ricegrass, needle-and-thread, bottlebrush squirreltail, and alkali sacaton. Forbs include 

tufted evening primrose, Paiute suncup, Geyer’s milkvetch, sharpleaf penstemon, and various 

lupines. Dunes cover about 6,300 acres on the Refuge and are primarily located on the east side of 

Harney Lake and as islands on Malheur Lake. 

Regional Distribution, Condition, and Trends 

Possibly because of harsh conditions, constantly shifting sand and specific adaptations of the plants 

that inhabit these sites, this habitat has fewer invasive weed issues than other upland types on the 

Refuge. Some invasive weeds, such as Russian thistle, are present, but their extent is very limited. 

The dunes are unstable and slowly shift over time. We have no trend data for the dunes but consider 

them basically pristine and unique habitat on the Refuge. 

Dunes are susceptible to invasion by exotic weeds such as Halogeton, povertyweed, and Russian 

thistle. These plants could change the dynamics of sand movement in the dunes and lead to increased 

stability, which would change the natural vegetation patterns on the dunes and compromise their 

integrity. Grazing by trespassing livestock occasionally occurs as well as use by trespassing allterrain vehicle riders. Both of these are a significant threat to the stability of the dunes. 

Key Species Supported 

Vertebrate wildlife associated with dunes are dependent on the associated vegetation and include 

many small mammals, including black-tailed jackrabbits, western cottontails, kangaroo rats, duskyfooted woodrats, and deer mice. Occasionally mule deer use the dunes to forage and seek cover. 

Shrub-steppe nesting birds such as sage thrashers, sage sparrows, and black-throated sparrows nest in 

the associated brush. Reptiles such as western fence lizards, side-blotched lizards, short horned 

lizards, and Pacific rattlesnakes frequent the dunes and some likely lay their eggs there. During high 

water periods, the sandy shorelines are used by foraging shorebirds. The priority ROC species under 

this habitat type is the sage sparrow, and more information about this species is listed below in Table 

4-11. 

Table 4-11. Dune Priority Resources of Concern Species 

Focal 

Species 

Habitat Structure and Attributes Life History 

Requirements 

Other Benefiting 

Species 

Sage 

sparrow 

Prefer large patches of contiguous 

sagebrush; semi-open, evenly spaced shrub 

habitat with big sagebrush and rabbitbrush 

as part of the community component. 

Shrub layer cover 10%-25% with a height 

of >19 inches (50 cm); herbaceous layer 

Breeding and 

foraging 

Sage thrasher, sagegrouse, loggerhead 

shrike, badger 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-31 

Focal 

Species 

Habitat Structure and Attributes Life History 

Requirements 

Other Benefiting 

Species 

cover >10%; open ground >10% (Altman 

and Holmes 2000; Martin and Carlson 

1998). 

Refuge Management Activities 

Dune habitats have received no direct management as these area lie within the RNA and proposed 

wilderness boundary for Harney Lake. Natural ecological factors continue to shape the dune terrain, 

without any significant human influences. The primary management objective is protection from 

trespassing livestock and people. 

4.3.12 Playa 

Overview 

Refuge playa habitats are located primarily in Harney Lake (a 40,000-acre playa when dry) and the 

Double-O. Stinking Lake is the second-largest refuge playa and is spring-fed and isolated from other 

surface hydrology. Total average refuge acres of playa habitats are approximately 29,000. During 

low-water periods, there are large playa areas in Mud Lake and a few along the east side of Malheur 

Lake. The flat playa surfaces that appear during drier periods are periodically flooded but generally 

too alkaline to support vegetation. They are bare or scattered with dead vegetation killed by 

floodwaters of the 1980s (Dugas 1996), and these unique habitats are often intermixed with saltgrass 

or desert salt-scrub communities. Evaporation of closed basin water during dry periods results in high 

levels of alkalinity and associated pH. During high-water events, the alkaline water is diluted, 

stimulating the temporary production of aquatic species. Playa soils are typically very deep and 

poorly drained. Virtually no vascular plants reside within Harney and Stinking lakes, with the 

exception of spring areas where steady freshwater inflows modify water chemistry. 

Regional Distribution, Condition, and Trends 

Generally, refuge playa habitats are in pristine condition with these communities least impacted by 

human actions or changed by environmental conditions. A few playas in the Double-O have been 

bisected by roads. Harney Lake is a designated Research Natural Area and wilderness study area, and 

has been protected for those values. Stinking Lake is designated as a Research Natural Area. 

When dry, playas are popular for off-road all-terrain vehicle use, which can cause soil compaction 

and erosion, reducing their resiliency and allowing soils to blow away. With access on the Refuge 

restricted, this is mostly a limited trespassing issue. Disruption of natural water supplies from local 

runoff by road construction or drainage systems could reduce the flood frequency and the wildlife 

value of playa habitats. 

Key Species Supported 

Playas systems are rich in invertebrates, such as brine flies and brine shrimp. They support breeding 

snowy plovers and occasionally American avocets and black-necked stilts. Harney Lake is the most 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-32 Chapter 4. Biological Environment 

important breeding site for snowy plovers in the Harney Basin and has supported over 400 breeders. 

When these habitats develop standing water, large numbers of waterfowl have been observed using 

the sites. Because they are rich in invertebrates, playas attract high numbers of migrant shorebirds 

when they are wet. When brine shrimp are abundant, the Refuge’s playas receive high use by 

Wilson’s and northern phalaropes, northern shovelers, ruddy ducks, gulls, and eared grebes. Peaks of 

over 15,000 phalaropes have been counted at Stinking Lake. The priority ROC species under this 

habitat type is the snowy plover, and more information about this species is listed below in Table 4-

12. 

Table 4-12. Playa Priority Resources of Concern Species 

Focal 

Species 

Habitat Structure and Attributes Life History 

Requirements 

Other Benefiting 

Species 

Snowy 

Plover 

Found in barren or sparsely vegetated 

alkaline or saline lakes, playas, and flats. 

Bare ground with little vegetation of any 

kind; nests are usually <0.8 mile from 

water; water levels for foraging are from 

0-1 inch (0-2 cm) deep (Page et al. 1985; 

Page et al. 1995). 

Breeding and 

foraging 

Phalaropes, eared 

grebe, northern 

shoveler, ruddy duck, 

shorebirds 

Refuge Management Activities 

These systems generally do not require any management other than protecting them from trespassing 

and off-road vehicle use. 

4.3.13 Cropland 

Overview 

Croplands are maintained on the Refuge to provide forage for fall-staging sandhill cranes and 

waterfowl. Grain fields are present at scattered locations in the Blitzen Valley. In the past two 

decades, refuge maintenance staff have planted and irrigated these fields. Winter wheat and spring 

barley are the primary crops planted, which are rotated among about 300 acres of grain fields. These 

fields are left unharvested for wildlife use. 

Grain crops are occasionally planted in bottoms of refuge impoundments as part of the drawdown 

cycle to reinvigorate wetland nutrients. 

Regional Distribution, Condition, and Trends 

Historically, a much higher percentage of the Blitzen Valley was managed as grain fields. Grain 

crops were extensive in the late 1930s through the 1950s to support fall migrants. Many fields that 

are now managed as wet meadows were leveled and ditched to allow farming. Approximately 1,300 

acres of grain fields were managed in the 1990s (USFWS 1990). Today about 80 acres of grain fields 

are managed on the Refuge. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-33 

Invasive weeds can be a threat to these lands if farming operations are terminated, with soils freshly 

tilled, and if the field is left idle and not restored. 

Key Species Supported 

Grain field farming has primarily been conducted to support fall-staging sandhill cranes. They are 

heavily used by cranes, Canada geese, mallards, northern pintails, and occasionally American 

wigeon. They are also used by mule deer, pronghorn, and upland game birds, including pheasants 

and California quail. Red-winged, yellow-headed, and Brewer’s blackbirds, as well as a variety of 

sparrows, also use them. 

Refuge Management Activities 

Crops are maintained on an annual basis. These areas are periodically treated for invasive weeds. 

4.3.14 Cold and Hot Springs 

Overview 

Springs occur throughout the Refuge, ranging from the southern end of the Blitzen Valley to the 

Double-O Unit. They provide stable, permanent sources of water for flood irrigation, pond filling, 

and/or maintenance, and wildlife. 

Regional Distribution, Condition, and Trends 

The ability of many springs to provide high quality aquatic habitat for fish and wildlife has been 

compromised due to the prevalence of common carp throughout the Refuge’s water system. Those 

areas that have remained carp-free provide abundant submergent vegetation and associated 

invertebrates. 

Key Species Supported 

Springs provide habitat for a diverse assemblage of macroinvertebrates, native plants, fish, other 

aquatic species, and wildlife. These areas provide essential habitat for spotted frog (breeding, 

feeding, and winter refugia) and trumpeter swan (warm-water springs are often the only open water 

available during the winter). 

Refuge Management Activities 

Areas adjacent to cold and hot springs are treated as needed for invasive weeds. 

4.3.15 Cliffs, Rimrock, and Outcroppings 

Overview 

Areas of steep basalt cliffs and outcroppings can be found along the sides of the Blitzen Valley and 

the south end of Mud and Harney lakes and in the Double-O Unit. This habitat type occurs within the 

refuge perimeters of the Blitzen and Double-O valleys. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-34 Chapter 4. Biological Environment 

Regional Distribution, Condition, and Trends 

Frequent wildfires have reduced the quality of vegetation occurring on and near cliff areas. The trend 

for the condition of these habitats is generally stable. Some sites have been modified in the past for 

use as sources of gravel and rock. 

Invasive weeds are a threat to the integrity of habitat surrounding cliffs and talus areas as they reduce 

the value of the sites for foraging wildlife. Disturbance of nesting raptors is an issue and human 

trespass needs to be minimized during the nesting period. 

Key Species Supported 

These areas provide nesting habitat for cliff dwelling birds, as well as various reptiles and are 

particularly important for nesting raptors, including golden eagles; prairie falcons; red-tailed hawks; 

and great-horned, screech, barn, and long-eared owls. Historically, they supported nesting peregrine 

falcons and they will likely soon reoccupy such refuge sites based on upward population trends and 

available habitat. These areas are used by mule deer, bighorn sheep, black-tailed jackrabbit, Nuttall’s 

cottontail, yellow-bellied marmots, golden-mantled ground squirrels, and bushy-tailed and desert 

woodrats. Many lizard and snake species are associated with this habitat type and some of the sites 

support rattlesnake hibernacula, especially in the Double-O Unit. 

Refuge Management Activities 

These systems generally do not require any management other than protecting them from trespassing. 

4.4 Major Species Groups 

4.4.1 Migratory and Resident Birds 

Waterfowl 

The Refuge supports several priority waterfowl species that are highlighted in the North American 

Waterfowl Management Plan (North American Waterfowl Management Plan Committee 1998). 

Species present that are identified as “high” priority in the plan and which use the Refuge are tule 

greater white-fronted goose, northern pintail, mallard, and lesser scaup. Most of the refuge use for 

these high-priority species is provided during migration periods. However, substantial numbers of 

mallards nest on the Refuge with some nesting by pintail and lesser scaup. Additionally, “other” 

priority waterfowl species identified in the plan use the Refuge or the area surrounding the Refuge, 

including Pacific greater white-fronted goose, Wrangel Island snow goose, wood duck, redhead, 

canvasback, ring-necked duck, and American wigeon. Most refuge use is migratory, but breeding 

pairs of wigeon, canvasback, ring-necked, and redhead ducks are observed each year. The Refuge 

also supports a breeding Rocky Mountain population of trumpeter swans, which are a priority for the 

Pacific Flyway. 

Use of the Refuge is substantial for many of these waterfowl species and varies with habitat 

conditions. A comparison of peak refuge counts, conducted in the 1980s and 1990s during spring and 

fall migration, with annual the Pacific Flyway midwinter population indices shows that the Refuge 

supported up to the following percentages for each species: 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-35 

 66 percent of the white goose (snow and Ross’s) population (spring 1996) 

 63 percent of the American wigeon population (fall 1993) 

 48 percent of the tundra swan population (in fall 1980 after carp control on Malheur Lake) 

 40 percent of the American green-winged teal population (fall 1993) 

 24 percent of the ruddy duck population (spring 1995) 

 22 percent of the northern shoveler population (fall 1993) 

 10 percent of the northern pintail population (spring 1996) 

 5 percent of the mallard population (fall 1996) 

Additionally, refuge counts for both redheads and canvasbacks exceeded the Pacific Flyway 

midwinter indices (328 percent for redheads in fall 1992 and 148 percent for canvasbacks in fall 

1995). However, it should be noted that the midwinter counts do not include Mexico, where 

substantial numbers of redheads and canvasbacks winter. 

Tule and Pacific greater white-fronted geese, snow geese, and Ross’s geese use the Refuge, primarily 

during migration. Tule geese primarily use the marshy areas on the north side of Malheur Lake in the 

fall, while white geese and Pacific white-front geese use the area more extensively in the spring. 

They use the lakes for night roosting and forage in irrigated meadows on the Refuge in the north 

Blitzen Valley and Double-O. However, it should be noted that the majority of these birds forage offrefuge on the Silvies River floodplain. Large numbers of western Canada geese winter here. 

Breeding waterfowl most commonly found on the Refuge include western Canada geese, cinnamon 

teal, mallard, gadwall, redhead, northern shoveler, northern pintail, American wigeon, canvasback, 

and ruddy duck. Several other species breed here but in much lower densities. A small flock of 

resident trumpeter swans use the Refuge year-round and nest in the Blitzen Valley. 

Waterfowl annual production has declined from production numbers of over 100,000 birds to 

between 50,000 and 60,000 annually by the 1980s (Cornely, 1982). A precipitous decline occurred in 

the early 1950s which was strongly suspected to be correlated with expanding carp populations and 

degradation of Malheur Lake aquatic habitats. Waterfowl production has rebounded from the lows of 

the 1960s but still remains less than half of historic production levels (Cornely, 1982). Information 

on production in the last decade is incomplete. 

Waterbirds 

Thirty different species of waterbirds occur on the Refuge. The Refuge supports several colonial 

waterbird species identified as priority species in the Intermountain West Waterbird Conservation 

Plan (Ivey and Herziger 2006), including greater sandhill cranes, western and Clark’s grebes, 

American white pelicans, California gulls, and Forster’s terns. 

Greater sandhill cranes are also listed as a sensitive species in Oregon. Malheur supports the highest 

number of breeding greater sandhill cranes of any refuge in the western United States. A statewide 

pair survey in 2000 found 245 pairs on the Refuge, 21 percent of the Oregon population (Ivey and 

Herziger 2000). 

Comparing peak refuge counts of nesting waterbirds with population estimates for the Great Basin 

bird conservation region, most colonial waterbird numbers peak counts exceeded 10 percent of 

regional populations. The Refuge supported 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-36 Chapter 4. Biological Environment 

 20,500 breeding white-faced ibises (35 percent of regional population in 1998); 

 7,782 breeding western and Clark’s grebes (50 percent of the regional population in 1983); 

 4,090 breeding American white pelicans (15 percent of the regional population in 1988); and 

 1,730 breeding great egrets (77 percent of the regional population in 1983). 

The Refuge also supports high numbers of breeding Franklin’s gulls in good water years. The Refuge 

also supports very high numbers of sora, Virginia rails, American coots, and American bitterns. 

Nesting populations fluctuate annually and quite dramatically depending on water levels and habitat 

conditions. Populations have disappeared during drought conditions and then rebounded with rising 

water levels. Populations such as white pelican (nesting on Malheur and Harney Lakes and in the 

Blitzen Valley) have moved as habitat conditions changed. 

Shorebirds 

The Refuge provides vital habitat for a wide variety of shorebirds. Twenty-seven shorebird species 

are found on the Refuge during different seasons of the year. The most common migrant species are 

the western sandpiper, long-billed dowitcher, Wilson phalarope, American avocet, and common 

snipe. From 1990 to 1995, the Refuge participated in the Pacific Flyway Project (Ivey et al. 1995), a 

study coordinated by Point Reyes Bird Observatory. Shorebird numbers were counted each spring 

and fall when the migrating shorebirds were using the Refuge as a stopover site (Figure 4-1). Total 

peak numbers exceeded 20,000 individuals during migration. Using peak numbers of shorebirds 

counted along the Pacific coast as estimates of Pacific Flyway populations (Page et al. 1999), refuge 

uses were as follows: the western sandpiper peak was <0.5 percent of the Pacific Flyway population, 

the long-billed dowitcher peak was 4.4 percent, and the American avocet peak was 10.8 percent. 

Malheur, Mud, Harney, and Stinking lakes provide most of the shorebird habitat on the Refuge and 

within the Harney Basin. Other important shorebird habitat on the Refuge can be found in the 

Double-O and Blitzen Valley units. Stinking Lake is an especially important shorebird use area. For 

example, Littlefield and Paullin (1976) documented 8,300 Wilson’s phalaropes and 10,000 American 

avocets there on August 21, 1975. These birds were likely attracted to crustaceans and brine flies, 

which are abundant when saline playa lakes are at low levels and salts are concentrated. Breeding 

snowy plovers use Harney Lake and other refuge playas, and the Refuge supports over 400 breeding 

adults in good years. 

Raptors 

Twenty-three species of raptors have been recorded on the Refuge. The recorded species consist of 

osprey, bald eagle, northern harrier, sharp-shinned hawk, cooper’s hawk, northern goshawk, redshouldered hawk, Swainson’s hawk, red-tailed hawk, rough-legged hawk, golden eagle, American 

kestrel, merlin, peregrine falcon, prairie falcon, barn owl, flammulated owl, western screech-owl, 

great horned owl, burrowing owl, long-eared owl, short-eared owl, and northern saw-whet owl. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-37 

2946

9278

4111

18191

20887

7712

4102 4611

10238

12059

Spring Fall

0

5000

10000

15000

20000

25000

1990 1991 1992 1993 1994

Figure 4-1. Total shorebird numbers from counts conducted at Malheur National Wildlife 

Refuge during the Pacific Flyway Project, 1990-1994. 

Passerines 

The Refuge supports at least 130 species of passerines, many of them identified as priority species by 

the Oregon and Washington Partners in Flight (Altman and Homes 2000). Riparian-dependent 

priority species include willow flycatchers, yellow warblers, Bullock’s orioles, and yellow-breasted 

chats. The Refuge also supports the largest local population of bobolinks in the western U.S. 

Passerine species found in the uplands include loggerhead shrike, sage sparrow, sage thrasher, blackthroated sparrow, lark sparrow, and Brewer’s sparrow. 

Other Birds 

Thirty-four species of non-passerine birds are found on the Refuge, including five species of gulls, 

three species of hummingbird, and seven species of woodpecker. 

4.4.2 Fisheries 

Native Fishes 

The Harney Basin, because of historic connections with the Columbia River drainage, supports a fish 

fauna mirroring the native fishes of the Columbia, with a few species absent or undetected, before 

they disappeared. A diverse assemblage of native fishes inhabit the Refuge, including the Great 

Basin redband trout, bridge lip sucker, coarse scale sucker, chisel mouth, northern pikeminnow, redsided shiner, mountain whitefish, longnose and speckled dace, and Malheur mottled sculpin. Of these 

species, redband trout and Malheur mottled sculpin are listed as Oregon State-sensitive species. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-38 Chapter 4. Biological Environment 

Non-native Fish Species 

A number of non-native fish are present in the Refuge’s permanent wetlands, rivers, impoundments, 

and lakes. Introduced fish include common carp, green sunfish, largemouth bass, rainbow trout, 

bluegill, yellow bullhead, brown bullhead, black bullhead, mosquito fish, yellow perch, 

pumpkinseed, and white crappie. Many of the introduced species were stocked by the State of 

Oregon for recreational fisheries. Other species invaded the Refuge during flood events. 

4.4.3 Other Wildlife and Plants 

Land Mammals: Fifty-eight species of mammals have been observed on the Refuge. The muskrat is 

the most conspicuous mammal in Malheur Lake and has an important influence on the marsh 

ecology. Like waterbird populations, numbers of muskrats fluctuate primarily in response to habitat 

conditions and, to a lesser extent, disease. The benefit of muskrats to a marsh results from their 

feeding and lodge-building activities. By cutting emergent vegetation for food, muskrats create an 

interspersed habitat more desirable for waterfowl than pure stands. Muskrat lodges provide attractive 

and productive nest sites for Canada geese and trumpeter swans. 

Deer mice, montane voles, Great Basin pocket mice, and least chipmunks made up 91 percent of the 

small mammals captured between 1973 and 1975 (Feldhamer 1979). Other mammals include 

pronghorn, mule deer, beaver, raccoon, coyote, bobcat, mink, long-tailed weasel, bats, and blacktailed jackrabbit. 

Reptiles and Amphibians: The following amphibians occur on the Refuge: long-toed salamander; 

great basin spadefoot, pacific tree frog, western toad, Columbia spotted frog, and bullfrog. 

The following reptiles occur on the Refuge: western fence lizard, sagebrush lizard, side blotched 

lizard, short-horned lizard, western skink, rubber boa, racer, striped whipsnake, gopher snake, 

common garter snake, western terrestrial garter snake, night snake, and western rattlesnake. 

The following species occur near the Refuge, but no known specimens have been collected on the 

Refuge: collared lizard, leopard lizard, desert horned lizard, western whiptail, and western ground 

snake. 

Invertebrates: At least 54 species of butterflies and dragonflies occur on the Refuge. There is a great 

diversity of aquatic macroinvertebrates due to the diversity of aquatic habitats. No comprehensive list 

of these organisms exists for the Refuge. 

4.5 Threatened, Endangered, and Sensitive Species 

4.5.1 State or Federally Listed Species Known to Occur on the Refuge 

One goal of the Refuge System is “To conserve, restore where appropriate, and enhance all species 

of fish, wildlife, and plants that are endangered or threatened with becoming endangered.” In the 

policy clarifying the mission of the Refuge System, it is stated, “We protect and manage candidate 

and proposed species to enhance their status and help preclude the need for listing” (16 U.S.C. 1531-

1543; 87 Stat. 884). 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-39 

In accordance with the above, the planning team considered all species with Federal or State status in 

the planning process. Table 4-13 lists species that are federally endangered, threatened, or candidate 

species and are known to occur on or near Malheur Refuge. A discussion of the federally listed 

candidate species follows the table in Section 4.5.2. 

A total of 19 Federal species of concern (declining or in need of conservation) are known to occur or 

are likely to occur on the Refuge: least bittern, white-faced ibis, black tern, ferruginous hawk, 

burrowing owl, yellow-breasted chat, willow flycatcher, sage-grouse, mountain quail, Lewis’ 

woodpecker, redband trout, fringed myotis, long-legged myotis, silver-haired bat, small-footed 

myotis, spotted bat, Townsend’s big-eared bat, Yuma myotis, and Preble’s shrew. Among this group 

the willow flycatcher and redband trout were selected as focal species whose requirements indicating 

the habitat parameters that would also support a large group of other species using these areas. 

Table 4-13. Federally Listed Species Known to Occur on or Adjacent to Malheur Refuge 

Common Name Scientific Name Federal Status* Current Occurrence on 

Refuge 

Malheur wire-lettuce Stephanomeria 

malheurensis 

Endangered Adjacent to Refuge 

Great Basin Columbia 

spotted frog 

Rana luteiventris Candidate species Page Springs, Mud Creek, 

Double-O Springs 

Yellow-billed cuckoo Coccyzus americanus Candidate species Occasional migrant according to 

historic records 

Greater sage-grouse Centrocercus 

urophasianus 

Candidate species Incidental and adjacent to 

Refuge 

4.5.2 Habitat Needs, Conditions, and Trends of Federally Listed, Proposed, or 

Candidate Species 

Malheur Wire-lettuce: This annual plant is not present on the Refuge but is located on public lands 

adjacent to the Refuge. It is found on top of a dry, broad hill on volcanic soil intermixed with layers 

of limestone. Dominant plants at the site are big sagebrush, gray rabbitbrush, green rabbitbrush, and 

cheatgrass. Malheur wire-lettuce may be one of the few species able to survive on and around the 

otherwise barren harvester ant hills at the site (USFWS 1991). 

This plant is in great danger due to its small population size. Natural fluctuations in population 

numbers occur in response to variations in annual rainfall and spring frosts and are particularly 

problematic for small populations. Immediate threats include competition from cheatgrass and 

predation by native herbivores, such as black-tailed jackrabbits. Currently, there are no plans to 

introduce this species in appropriate refuge habitats. The Refuge is working closely with USFWS 

Ecological Services and other State and Federal agencies on the status of this plant. 

Great Basin Columbia Spotted Frog: The Columbian spotted frog consists of two distinct 

populations: the Northern and Great Basin populations. The Refuge is believed to have a population 

of the Great Basin distinct population segment (DPS) of the Columbia spotted frog. The Great Basin 

Columbia spotted frog is designated as a Federal candidate species for listing under the Endangered 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-40 Chapter 4. Biological Environment 

Species Act. However, the geographic distribution of the Northern and Great Basin DPS Columbia 

spotted frogs overlap in eastern Oregon, quite possibly on the Refuge, given the available data. The 

Northern Columbia spotted frog is not designated as a Federal candidate species. Sporadic 

monitoring of spotted frogs has occurred for over two decades on the Refuge; however, refuge-wide 

species distribution and genetic analyses have yet to be completed. Known populations within the 

northwest portion of the Refuge appear to be geographically isolated from populations approximately 

25 miles south within the Blitzen River watershed. 

There are numerous threats to Columbia spotted frogs (e.g., habitat destruction, fragmentation and/or 

degradation of wetlands, non-native predatory species, fire and fire suppression, contaminants). The 

habitat present on the Refuge needs to be assessed to determine water for breeding, summer habitat, 

and winter refugia to aid in the conservation of the species. In addition, results from the assessment 

will assist Refuge management and biologists to understand the distribution of Columbia spotted 

frogs on the Refuge, help facilitate the development of an annual egg mass monitoring protocol, and 

identify the role the Refuge plays in Columbia spotted frog conservation. 

Yellow-billed Cuckoo: The yellow-billed cuckoo has been documented on the Refuge; however, no 

breeding has been recorded and cuckoo observations are considered accidental. Refuge sightings 

account for most of the recent sightings of the yellow-billed cuckoo in Oregon (USFWS 2008b). 

The primary reason for the decline of the yellow-billed cuckoo west of the Rocky Mountains is loss 

of tall streamside habitat. They tend to prefer trees with extensive canopies, such as cottonwood, 

which are not abundant on Malheur Refuge. 

Greater Sage-grouse: This species is a rare user of the Refuge, but it uses public lands adjacent to 

the Refuge. Occasional sighting have been documented of sage-grouse watering on the East Canal 

during drought years. They have also occasionally been observed foraging in meadows at the 

northern end of the Double-O in late summer. Other uses have not been documented. 

4.6 Invasive and Nuisance Species 

4.6.1 Exotic and Invasive Plant Species 

Invasive plant species infect and degrade many of the aquatic and terrestrial habitats on the Refuge. 

Some highly invasive species (e.g., pepperweed and reed canarygrass) can produce monotypic stands 

that completely displace native and desirable plant communities. These native communities are 

essential habitat that supports high-priority species and species groups on the Refuge (e.g., migratory 

birds). The Refuge’s overall strategy to manage invasive plants is to use an IPM approach. For IPM, 

mechanical, physical, biological, and chemical methods are used to control invasive plants as a basis 

for achieving desirable habitat conditions. Many factors affect efficacy of control efforts for invasive 

plants. Aerial spraying is limited because treated ditches typically cannot be charged soon after 

applications based upon pesticide label restrictions. For species with extensive infestations 

throughout the Refuge (e.g., pepperweed), the Refuge’s strategy involves containment to prevent 

spread to uninfested areas. 

There are nine species of plants found adjacent to or on the Refuge (Table 4-14) which are classified 

by the Oregon Department of Agriculture as noxious weeds. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-41 

Table 4-14. Oregon Department of Agriculture Noxious Weeds Found on or Adjacent to 

Malheur Refuge 

Common Name Scientific Name 

Canada thistle Cirsium arvense 

Diffuse knapweed Centaurea diffusa 

Medusahead rye Taeniatherum caput-medusa 

Perennial pepperweed Lepidium latifolium 

Puncture vine Tribulus terestris 

Russian knapweed Acroptilon repens 

Salt cedar Tamarix ramosissima 

Scotch thistle Onopordum acanthium 

Whitetop Cardaria draba 

The plants listed below are of the highest priority for the Refuge and are part of invasive species 

management. 

Perennial Pepperweed: Flooding during the mid-1980s initially spread pepperweed throughout the 

Refuge and adjacent private lands; subsequent drought (1988-1992) exacerbated this invasive plant 

problem. There are approximately 30,000 acres of perennial pepperweed infestation on the Refuge, 

likely because the water delivery system has spread seeds throughout the system. Pepperweed 

represents a significant threat to the Refuge’s capability to meet refuge purposes and habitat 

management objectives, especially those related to migratory birds. Pepperweed infests and forms 

monotypic stands and displaces grass/shrub uplands, wet meadows, and riparian habitat that are used 

by breeding waterfowl, cranes, and landbirds. Because it infests meadows, it can jeopardize the 

Refuge’s haying program, which provides short-grass habitat used by breeding aquatic migratory 

birds. Pepperweed also infests and compromises fire breaks. Moreover, areas disturbed during 

riparian restoration may become infested with pepperweed. 

Phragmites, Reed Canarygrass, and Other Undesirable Plant Species: Plants such as these are also 

displacing native/desirable species in marsh/meadow complexes. Based on habitat surveys, 

approximately 80 percent of the 60,000 wetland and meadow acres on the Refuge are infested to 

some degree with invasive plants. As a result, habitat quality for breeding migratory birds is 

declining relative to the degree of infestations. 

Russian Olive: This species spread across refuge lands around Malheur and Mud lakes during the 

floods of the 1980s. 

4.6.2 Exotic Wildlife Species 

Common carp are the most invasive and detrimental wildlife species that inhabits the Refuge. Carp 

first invaded the Refuge in the late 1930s or early 1940s. The Silvies River provided access to 

Malheur Lake, and carp migrated up the Blitzen River and invaded the wetlands of the Blitzen 

Valley. Carp invaded the Double-O Unit during the early 1950s when the natural sand dune barrier 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-42 Chapter 4. Biological Environment 

separating Malheur and Mud lakes was breached and allowed water and carp from Malheur and Mud 

lakes to enter Harney Lake. By the early 1960s carp had successfully invaded virtually all aquatic 

systems within the Refuge and surrounding private lands. Before carp invaded the Refuge, duck 

production averaged over 111,000 ducks annually in the 1940s and peaked at 147,000 ducks in 1948. 

After the carp population became established, duck production has averaged less than 30,000 

annually (Ivey et al. 1998). Carp compete directly with waterfowl and waterbirds for aquatic 

invertebrates and vegetation, and their benthic foraging causes a detrimental decrease in water 

quality. 

A small population of bullfrogs has established at the south end of the Blitzen Valley. This invasive 

species could be a threat to the Oregon spotted frog population because of predation or habitat 

competition. 

4.7 Wildlife and Habitat Research, Inventory, and Monitoring 

The Refuge has a long history of strong biological monitoring and research. Many projects are 

collaborative efforts between the Refuge and other Service programs, agencies, nongovernmental 

organizations, and universities. 

4.7.1 Monitoring 

Table 4-15 summarizes surveys conducted by refuge biological staff in the late 1990s. Due to 

changes in staff and budget cuts, many of these surveys were discontinued in the last decade. 

Table 4-15. Biological Surveys Conducted at Malheur Refuge during the Peak of Biological 

Monitoring in the Late 1990s 

Survey Type Survey Type 

Mid-winter waterfowl survey (flight) Migration waterfowl surveys (5 flights) 

Muskrat house surveys Raptor survey routes (4) 

Read goose neck collars Bald eagle roost counts 

Use telemetry to scan for radio-marked waterfowl Golden eagle nest survey 

Crane pair survey Water temperature monitoring (Hobotemps) 

Goose pair survey Monitor goose, duck and crane nest success 

Predator survey Neotropical migrant monitoring station (mist net; 

spring, fall) 

Common raven roost surveys Colonial waterbird surveys 

North American migration count Duck and waterbird pair survey 

Dove coo count (2 routes) Spotted frog surveys 

Trumpeter swan production survey Duck brood survey 

Bobolink survey Snowy plover survey 

Upland habitat monitoring Breeding bird survey routes (7) 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-43 

Survey Type Survey Type 

Botulism monitoring Aquatic plant surveys 

Tule goose surveys Fall crane use surveys 

Fall crane survey for Pacific Flyway 2 Christmas bird counts (Sodhouse, P Ranch) 

4.7.2 Refuge Research 

Many research studies have been conducted at Malheur National Wildlife Refuge since the Refuge 

was established. Projects are listed below in chronological order and a complete copy is on file at 

Malheur Refuge library, summarized in the narratives or available as literature cited: 

 Breeding Habits of the Canvasback, Nyroca valisineria (Wilson), on the Malheur National 

Wildlife Refuge (Erickson 1942). 

 Relationship between Land-use Patterns and Waterfowl Production at Malheur National 

Wildlife Refuge, 1964 (Jarvis 1965). 

 Breeding Biology of Greater Sandhill Cranes on Malheur National Wildlife Refuge, Oregon 

(Littlefield 1968; Littlefield and Ryder 1968). 

 Color Marking of Greater Sandhill Cranes on Malheur Refuge, Oregon. The study is ongoing 

and was initiated by Carroll Littlefield in the late 1960s. The objective of this study is to 

color mark greater sandhill cranes and monitor their movements and life history. Marking 

these birds helps document effects of land use practices on cranes breeding at Malheur 

Refuge and assess their migration and wintering movements, annual productivity, and 

behavior. 

 Land-use Patterns and Duck Production at Malheur National Wildlife Refuge (Jarvis and 

Harris 1971). 

 Distribution and Survival of Mallards Banded at Malheur National Wildlife Refuge (Jarvis 

and Furniss 1978). 

 Productivity of Greater Sandhill Cranes on Malheur National Wildlife Refuge, Oregon 

(Littlefield 1976). 

 An Ecological Study of the Common Raven (Corvus corax) at Malheur NWR and its Effects 

on the Nesting Success of Selected Waterfowl (Stiehl 1976, 1985; Stiehl and Trautwein 

1991). 

 Factors Affecting the Ecology of Small Mammals on Malheur National Wildlife Refuge 

(Feldhamer 1977). 

 Effects of Experimental Management Schemes on Production and Nesting Ecology of Ducks 

at Malheur National Wildlife Refuge (Clark 1977). This is a duck nesting ecology study. 

 The Breeding Biology of an Isolated Bobolink Population in Oregon (Wittenberger 1978). 

 Effects of Haying and Grazing on Duck Production in the Blitzen Valley (Unit 12) of 

Malheur National Wildlife Refuge, Oregon (Ivey 1979). 

 Historical Review and Status of Colonial Nesting Birds on Malheur National Wildlife 

Refuge, Oregon (Thompson et al. 1979). 

 Burning, Haying, Grazing, and Non-use of Flood Meadow Vegetation (Britton and Cornely 

1980; Britton and Sneva 1979). This study evaluated management effects on wet meadows. 

 Future Management of Malheur Lake Marsh: Recommendations of the Technical Advisory 

Committee (Summerfelt et al. 1980). 

 Waterfowl Production at Malheur National Wildlife Refuge, 1942-1980 (Cornely 1982). 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-44 Chapter 4. Biological Environment 

 History and Status of the Franklin’s Gull on Malheur National Wildlife Refuge, Oregon 

(Littlefield and Thompson 1981). 

 Malheur-Harney Lakes Basin Study, Oregon (Horton et al. 1983; Littlefield 1982; Paullin et 

al. 1977). 

 Manipulation of Flood Meadow Vegetation and Observations on Small Mammal Populations 

(Cornely et al. 1983). 

 Nesting History of Golden Eagles in Malheur-Harney Lakes Basin, Southeastern Oregon 

(Thompson et al. 1984). 

 Habitat Definition of Nesting Birds in the Double-O Unit, Malheur National Wildlife Refuge 

(Foster 1985). 

 Fire Ecology and Management in Plant Communities of Malheur National Wildlife Refuge 

Southeastern Oregon (Young 1986). 

 Effects of Cattle Grazing on Passerine Birds Nesting in Riparian Habitat (Taylor 1986). 

 A Summary of Trumpeter Swan Production on Malheur National Wildlife Refuge, Oregon 

(Cornely et al. 1985). 

 Autumn Sandhill Crane Habitat Use in Southeast Oregon (Littlefield 1986). 

 The Re-establishment of American White Pelican Nesting in the Malheur-Harney Lakes 

Basin, Oregon (Paullin et al. 1988). 

 Effects of Land Management on Nesting Success of Sandhill Cranes in Oregon (Littlefield 

and Paullin 1990). 

 Rough-legged Hawk Habitat Selection in Relation to Livestock Grazing on Malheur National 

Wildlife Refuge, Oregon (Littlefield et al. 1992). 

 Nests and Eggs of Colonial Birds Nesting in Malheur Lake, Oregon, with Notes on DDE 

(Cornely et al. 1993). 

 Population Trends of Small Mammals on Malheur Refuge, Oregon. This study was initiated 

in 1986 by Dr. David Kerley of Eastern Oregon State College at La Grande. The purpose is 

to monitor long-term trends in small mammal populations in Great Basin sagebrush and 

greasewood shrub communities. Field work only. No report. 

 Environmental Contaminants and Reproductive Success of Waterfowl, Stilts, and Coots at 

Malheur Refuge. This study was initiated by Dr. Charles Henny, of Patuxent Wildlife 

Research Center, Pacific Northwest Field Station, to investigate levels of contaminants in 

eggs of selected wetland species and to determine if contaminants were impacting production 

in these species. Field work only. No report. 

 Willow Flycatcher Reproductive Success, Population Dynamics, and Habitat Relationships. 

Jim Sedgwick of the National Ecology Research Center initiated this study in 1988. The 

study is designed to examine the extent and causes of variation in reproductive success and 

the survival, productivity, and habitat relationships of willow flycatchers at Malheur Refuge. 

Site tenacity, as related to reproductive success and habitat quality, predation, parasitism by 

brown-headed cowbirds, and environmental (habitat) correlates of reproductive success 

receive special attention. Field work only. No report. 

 Recovery of Vegetation at Malheur Lake Following Extensive Flooding (Spencer 1994). 

 Overview of Shorebird Abundance and Distribution in Wetlands of the Pacific Coast of the 

Contiguous United States. From 1990 to 1995, refuge staff participated in the Pacific Flyway 

project, a study coordinated by Point Reyes Bird Observatory (see Page et al. 1999). One 

count of Malheur, Mud, and Harney lakes was conducted each spring and fall using airboats. 

 Archaeological and Geomorphic Investigations of Prehistoric Sites on Malheur Lake. This 

study, conducted by Intermountain Research of Silver City, Nevada, examines the 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-45 

relationship of archaeological sites and the geomorphic processes that have shaped the 

landforms on Malheur, Mud, and Harney lakes. (Raven and Elston 1992) 

 A Radio-telemetry Study to Identify Sandhill Crane Colt Mortality Factors. In 1991, a radiotelemetry study was initiated by Gary Ivey to determine causes of crane colt mortality. This 

study continued through 1998 to provide data for better management of sandhill cranes on the 

Refuge. Field work only. No report. 

 Breeding Biology of Eared Grebes at Malheur National Wildlife Refuge. This study was 

conducted by Dr. Wendy Hill of Lafayette College in Pennsylvania. She studied two eared 

grebe colonies, one at Boca Lake and the other near the mouth of the Blitzen River in 

Malheur Lake. (Hill et al. 1997). 

 Use of Integrated Pest Management to Restore Meadows Infested with Perennial Pepperweed 

at Malheur National Wildlife Refuge (Kilbride et al. 1997). 

 Roaring Springs Ranch Riparian Bird Monitoring. A study to determine occurrence and 

abundance of riparian-dependent songbirds was initiated by refuge biologists on Roaring 

Springs Ranch. The Ranch signed a cooperative agreement with the Refuge and BLM 

regarding grazing practices along streams on their property and adjacent Federal land. This 

study was designed to monitor bird species during the breeding season to note changes in 

bird populations as the riparian zone along these creeks recovers. 

 Eastern Kingbird Study. From 2001 to 2010, Malheur Refuge has been the site of eastern 

kingbird studies that have shown a decline in the Malheur Refuge’s kingbird population 

along with an increase in the population of American crows. Field work only. No report. 

 Establishing Native Plants in Crested Wheatgrass Stands Using Successional Management 

(Fansler and Mangold 2007). Field work only. No report. 

 Factors Influencing Nest Success of Greater Sandhill Cranes at Malheur National Wildlife 

Refuge, Oregon (Ivey and Dugger 2008) 

 Geomorphic History and Current Channel Condition of the Donner und Blitzen River, 

Malheur National Wildlife Refuge, Oregon (Salant et al. 2010). 

 Migratory Behavior and Passage of Redband Trout (Oncorhynchus mykiss) in the Donner 

und Blitzen River, Oregon (Anderson 2009). 

4.8 Paleontological Resources 

Paleontological resources, also known as fossils, are the remains or traces of prehistoric plant and 

animal life that are found in the geologic formations in which they were originally buried. At 

Malheur Refuge fossils are found within volcanic ash deposits on the Refuge dating from the 

Pleistocene epoch (2.6 million to 11,700 years ago). Fossilized remains (vertebrae) of a camel-like 

species have been recovered from the site. The site may also contain additional fauna and flora, but 

other than a cursory examination by a paleontologist from the John Fossil Beds National Monument, 

there has not been any scientific investigation of the site. The site has regional importance as it 

encompasses a period of geologic time that has not been found elsewhere in eastern Oregon. 

Paleontological resources are considered to be nonrenewable, sensitive, scientific, and educational 

resources and are protected by the Paleontological Resource Preservation Act (P.L. 111-011 2009). 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-46 Chapter 4. Biological Environment 

4.9 References 

Altman, B. and A. Holmes. 2000. Conservation strategy for landbirds in the Columbia Plateau of 

eastern Oregon and Washington. Oregon-Washington Partners in Flight. The Plains, VA: 

American Bird Conservancy. 131 pp. 

Anderson, M.C. 2009. Migratory behavior and passage of redband trout (Oncorhynchus mykiss) in 

the Donner und Blitzen River, Oregon. M.S. thesis. Oregon State University, Corvallis. 

Bailey, R.G., P.E. Avers, T. King, and W.H. McNab. 1994. Eco-regions and sub-regions of the 

United States (map); supplementary table of map unit descriptions compiled and edited by 

W.H. McNab and R.G. Bailey. U.S. Forest Service. Washington, D.C. 

Beckham, S.D. 1995. Donner und Blitzen River Oregon: river widths, vegetative environment, and 

conditions shaping its condition, Malheur Lake to headwaters. Eastside Ecosystem 

Management Project. Walla Walla, WA. 

Bendire, C. 1875-1876. Notes on 79 of the birds observed in the neighborhood of Camp Harney, 

Oregon. Boston Society of Natural History Proceedings 18:153-168. 

Bird, F.H. 1975. Biology of the blue and tui chubs in East and Paulina lakes, Oregon. M.S. thesis. 

Oregon State University, Corvallis. 

Britton, C.M. and J.E. Cornely. 1980. Burning, haying, grazing, and non-use of flood meadow 

vegetation. 1980 progress report: Research in rangeland management, special report 586. 

Oregon Agricultural Experiment Station, Oregon State University. Corvallis, OR. 9 pp. 

Britton, C.M. and F.A. Sneva. 1979. Effects of haying and non-use on flood meadow vegetation. 

1979 progress report: research in rangeland management, special report 586. Oregon 

Agricultural Experiment Station, Oregon State University. Corvallis, OR. 9 pp. 

Bura, R.B. 2002. Ruddy duck (Oxyura jamaicensis) No. 696 in: A. Poole and F. Gill, eds. The birds 

of North America. The Academy of Natural Sciences, Philadelphia, PA, and the American 

Ornithologists’ Union, Washington, D.C. 

Clark, J.P. 1977. Effects of experimental management schemes on production and nesting ecology of 

ducks at Malheur National Wildlife Refuge. M.S. thesis, Oregon State University, Corvallis. 

Cooley, M.F. and M.L. Cooley. 2004. The transcribed diary of Eli Casey Cooley as he came across 

the Oregon Trail and the Meek Cutoff in 1845, by Michael F. and Mary Lou Cooley for the 

Officer-Cooley Family Association, November 2004. Available at: 

http://www.oregonpioneers.com/CooleyDiary.htm. 

Cornely, J.E. 1982. Waterfowl production at Malheur National Wildlife Refuge, 1942-1980. 

Transactions of North American Wildlife and Natural Resource Conference 47:559-571. 

Cornely, J.E., C.M. Britton, and F.A. Sneva. 1983. Manipulation of flood meadow vegetation and 

observations on small mammal populations. Prairie Naturalist 15:16-22. 

Cornely, J.E., E.L. McLaury, L.D. Napier, and S.P. Thompson. 1985. A summary of trumpeter swan 

production on Malheur National Wildlife Refuge, Oregon. Murrelet 66:50-55. 

Cornely, J.E., S.P. Thompson, C.J. Henny, and C.D. Littlefield. 1993. Nests and Eggs of colonial 

birds nesting in Malheur Lake, Oregon, with notes on DDE. Northwestern Naturalist 74:41-

48. 

Cullen, S.A., J.R. Jehl, Jr., and G.L. Nuechterlein. 1999. Eared Grebe. No. 433 in: A. Poole and F. 

Gill, eds. The birds of North America. The Academy of Natural Sciences, Philadelphia, PA, 

and the American Ornithologists’ Union, Washington, D.C. 

Custer, C.M. 1993. Life history traits and habitat needs of the redhead. Waterfowl management 

handbook. Leaflet 13.1.11. U.S. Fish and Wildlife Service. La Crosse, WI. 7 pp. 

Dechant, J.A., M.L. Sondreal, D.H. Johnson, L.D. Igl, C.M. Goldade, A.L. Zimmerman, and B.R. 

Euliss. 1999 (revised 2003). Effects of management practices on grassland birds: 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-47 

bobolink. U.S. Geological Survey, Northern Prairie Wildlife Research Center. Jamestown, 

ND. 24 pp. 

Dechant, J.A., D.H. Johnson, C.M. Goldade, J.O. Church, and B.R. Euliss. 2002. Effects of 

management practices on wetland birds: eared grebe. U.S. Geological Survey, Northern 

Prairie Wildlife Research Center. Jamestown, ND. 20 pp. 

Dechant, J.A., M.L. Sondreal, D.H. Johnson, L.D. Igl, C.M. Goldade, A.L. Zimmerman, and B.R. 

Euliss 2002. Effects of management practices on grassland birds: western meadowlark. U.S. 

Geological Survey, Northern Prairie Wildlife Research Center. Jamestown, ND. 33 pp. 

Drilling, N., R. Titman, and F. McKinney. 2002. Mallard (Anas platyrhynchos). No. 625 in: A. Poole 

and F. Gill, eds. The birds of North America. The Academy of Natural Sciences, 

Philadelphia, PA, and the American Ornithologists’ Union, Washington, D.C. 

Dubowy, P.J. 1996. Northern shoveler (Anus clypeata). No. 217 in: A. Poole and F. Gill, eds. The 

birds of North America. The Academy of Natural Sciences, Philadelphia, PA, and the 

American Ornithologists’ Union, Washington, D.C. 

Duebbert, H.F. 1969. The ecology of Malheur Lake and management implications. USDI, Fish and 

Wildlife Service. Harney County, OR. 24 pp. 

Dugas, D.P. 1996. Formation processes and chronology of dune islands at Malheur National Wildlife 

Refuge, Harney County, Oregon. Cultural Resource Series 12. USDI, Fish and Wildlife 

Service. Eugene, OR. 

Dzus, E.H. and R.G. Clark. 1997. Overland travel, food abundance, and wetland use by mallards: 

relationships with offspring survival. Wilson Bulletin 109:504-515. 

Evans, R.M. and F.L. Knopf. 1993. American white pelican (Pelecanus erythrorhyncos). No. 57 in: 

A. Poole and F. Gill, eds. The birds of North America. The Academy of Natural Sciences, 

Philadelphia, PA, and the American Ornithologists’ Union, Washington, D.C. 

Erickson, R.C. 1942. Breeding habits of the Canvasback, Nyroca valisineria (Wilson), on the 

Malheur National Wildlife Refuge. M.S. thesis. Iowa State College, Ames. 

Fansler, V.A. 2007. Establishing native plants in crested wheatgrass stands using successional 

management. M.S. thesis. Oregon State University, Corvallis. 

Fansler, V.A. and J. Mangold. 2007. Establishing native plants in crested wheatgrass stands using 

successional management. Master’s thesis. Oregon State University, Corvallis. 

Feldhamer, G.A. 1977. Factors affecting the ecology of small mammals on Malheur National 

Wildlife Refuge. Ph.D. Dissertation, Oregon State University, Corvallis, OR. 94 pp. 

Feldhamer, G.A. 1979. Vegetative and edaphic factors affecting abundance and distribution of small 

mammals in southeast Oregon. Great Basin Naturalist 39:207-218. 

Finholt, S.L. 1994. Status and distribution of the Laridae in Wyoming through 1986. Great Basin 

Naturalist 54:342-350. 

Finholt, S.L. and S.H. Anderson. 1995. Diet and prey use patterns of the American white pelican 

(Pelacanus erythrorhynchos) nesting at Pathfinder Reservoir, Wyoming. Colonial Waterbirds 

18(1)58-68. 

Foster, C.L. 1985. Habitat definition of nesting birds in the Double-O Unit, Malheur National 

Wildlife Refuge. M.S. thesis. Humboldt State University, Arcata, CA. 

French, G. 1964. Cattle country of Peter French. Portland, OR: Binford and Mort. 

Gabrielson, I.N. and S.G. Jewett. 1940. Birds of Oregon. Corvallis, OR: Oregon State College. 

Greer, M.J. 2009. An evaluation of habitat use and requirements for grassland bird species of greatest 

conservation need in central and western South Dakota. M.S. thesis. South Dakota State 

University, Brookings. 

Hill, W.L., K.J. Jones, C.L. Hardenbergh, and M. Browne. 1997. Nest distance mediates the costs of 

coloniality in eared grebes. Colonial Nesting Birds 20(3):470-477. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-48 Chapter 4. Biological Environment 

Horton, S.K., C.D. Littlefield, D.G. Paullin, and R.E. Vorderstrasse. 1983. Migratory bird 

populations and habitat relationships in Malheur-Harney Lakes Basin, Oregon. U.S. Fish and 

Wildlife Service. Portland, OR. 

Ivey, G.L. 1979. Effects of haying and grazing on duck production in the Blitzen Valley (Unit 12) of 

Malheur National Wildlife Refuge, Oregon. Unpublished report on file, Malheur Refuge. 

Princeton, OR. 35 pp. 

Ivey, G.L., J.E. Cornely, and B.D. Ehlers. 1998. Carp impacts on waterfowl at Malheur National 

Wildlife Refuge, Oregon. North American Wildlife and Natural Resources Conference 

63:66-74. 

Ivey, G. L. and B.D. Dugger. 2008. Factors influencing greater sandhill crane nest success at 

Malheur National Wildlife Refuge, Oregon. Waterbirds 31:52-61. 

Ivey, G.L. and C.P. Herziger. 2000. Distribution of greater sandhill crane pairs in Oregon, 1999/00. 

Oregon Department of Fish and Wildlife nongame technical report no. 03-01-00. Portland, 

OR. 

Ivey, G.L. and C.P. Herziger, compilers. 2006. Intermountain West waterbird conservation plan. 

Version 1.2. U.S. Fish and Wildlife Service Pacific Region. Portland, OR. 205 pp. 

Ivey, G.L., C. Littlefield, and D.G. Paullin 1995. Abundance and migration patterns of migrant 

shorebirds in the Harney Basin, Oregon. Unpublished report on file, Malheur Refuge. 

Princeton, OR. 

Jarvis, R.L. 1965. Relationship between land-use patterns and waterfowl production at Malheur 

National Wildlife Refuge, 1964. M.S. thesis. Humboldt State College, Arcata, CA. 

Jarvis, R.L. and S.B. Furniss. 1978. Distribution and survival of mallards banded at Malheur National 

Wildlife Refuge. Northwest Science 52:292-302. 

Jarvis, R.L. and S.W. Harris. 1971. Land-use patterns and duck production at Malheur National 

Wildlife Refuge. Journal of Wildlife Management 35:767-773. 

Kilbride, K.M., F.L. Paveglio, D.A. Pyke, M.S. Laws, and J.H. David. 1997. Use of Integrated pest 

management to restore meadows infested with perennial pepperweed at Malheur National 

Wildlife Refuge. Pages 31-35 in: Management of perennial pepperweed (tall whitetop). 

Special report 972. Eastern Oregon Agricultural Research Center. Burns, OR. 

Knopf, F.L. and J.L. Kennedy. 1981. Differential predation by two species of piscivorous birds. 

Wilson Bulletin 93:554-556. 

Knopf, F.L. and J.A. Sedgwick. 1992. An Experimental study of nest-site selection by yellow 

warblers. Condor 94:734-742. 

Langston, N. 2003 Where land and water meet: a western landscape transformed. Seattle, WA: 

University of Washington Press. 

Lanyon, W.E. 1994. Western meadowlark (Sturnella neglecta). No 104. in: A. Poole and F. Gill, eds. 

The birds of North America. The Academy of Natural Sciences, Philadelphia, PA, and the 

American Ornithologists’ Union, Washington, D.C. 

LeSchack, C., S. McKnight, and G. Hepp. 1997. Gadwall (Anas strepera). No. 283 in: A. Poole and 

F. Gill, eds. The birds of North America. The Academy of Natural Sciences, Philadelphia, 

PA, and the American Ornithologists’ Union, Washington, D.C. 

Littlefield, C.D. 1968. Breeding biology of the greater sandhill crane on Malheur National Wildlife 

Refuge, Oregon. M.S. thesis. Colorado State University, Fort Collins. 

Littlefield, C.D. 1976. Productivity of greater sandhill cranes on Malheur National Wildlife Refuge, 

Oregon. Proceedings of the International Crane Workshop 1:86-92. 

Littlefield, C.D. 1982. Malheur-Harney Lakes Basin study, Oregon. Report no. 3: 1979-1981. 

Unpublished report. Malheur National Wildlife Refuge. Princeton, OR. 

Littlefield, C.D. 1986. Autumn sandhill crane habitat use in southeast Oregon. Wilson Bulletin 

98:131-137. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-49 

Littlefield, C.D. 1995. Sandhill crane nesting habitat, egg predators, and predator history on Malheur 

National Wildlife Refuge, Oregon. Northwestern Naturalist 76:137-143. 

Littlefield, C. D. and D.G. Paullin. 1976. Shorebird use 1975: Malheur-Harney Lakes Basin, Oregon. 

Unpublished report. Malheur National Wildlife Refuge. Princeton, OR. 

Littlefield, C.D. and D.G. Paullin. 1990. Effects of Land management on nesting success of sandhill 

cranes in Oregon. Wildlife Society Bulletin 18:63-65. 

Littlefield, C.D. and R.A. Ryder. 1968. Breeding biology of greater sandhill cranes on Malheur 

National Wildlife Refuge, Oregon. Transaction of the North American Wildlife Natural 

Resource Conference 33:444. 

Littlefield, C.D. and S.P Thompson. 1981. History and status of the Franklin’s gull on Malheur 

National Wildlife Refuge, Oregon. Great Basin Naturalist 4:440-444. 

Littlefield, C.D., S.P. Thompson, and R.S. Johnstone. 1992. Rough-legged Hawk habitat selection in 

relation to livestock grazing on Malheur National Wildlife Refuge, Oregon. Northwestern 

Naturalist 73:80-84. 

Low, J.B. 1945. Ecology and management of the redhead, Nyroca Americana, in Iowa. Ecological 

Monographs 15:35-69. 

Lowther, P.E., C. Celeda, N.K. Klien, C.C. Rimmer, and D.A. Spector. 1999. Yellow warbler 

(Dendroica petechia). No. 454 in: A. Poole and F. Gill, eds. The birds of North America. The 

Academy of Natural Sciences, Philadelphia, PA, and the American Ornithologists’ Union, 

Washington, D.C. 

Martin, J.W. and B.A. Carlson. 1998. Sage sparrow (Amphispiza belli). No. 326 in: A. Poole and F. 

Gill, eds. The birds of North America. The Academy of Natural Sciences, Philadelphia, PA, 

and the American Ornithologists’ Union, Washington, D.C. 

McMahon, B.F. 1991. Foraging behaviour of American white pelicans (Pelecanus erythrorhynchos) 

M.Sc. thesis. University of Manitoba, Winnipeg, Manitoba, Canada. 

McMahon, B.F. and R.M. Evans. 1992. Nocturnal foraging in the American white pelican. Condor 

94:101-109. 

Moskwik, M.P. and M.A. O’Connell. 2006. Male and female reproductive strategies in the 

polygynous bobolink. Northwest Science 80:108-115. 

Mowbray, T.B. 2002. Canvasback (Aythya valisineria). No. 659 in: A. Poole and F. Gill, eds. The 

birds of North America. The Academy of Natural Sciences, Philadelphia, PA, and the 

American Ornithologists’ Union, Washington, D.C. 

Mullins, W.H. and E.G. Bizeau, 1978. Summer foods of sandhill cranes in Idaho. Auk 95:175-178. 

North American Waterfowl Management Plan Committee. 1998. North American waterfowl 

management plan: expanding the vision. 1998 update. United States Department of Interior, 

SEMARNAP Mexico, and Environment Canada. 43 pp. 

ODFW (Oregon Department of Fish and Wildlife). 2006. Oregon conservation strategy. Oregon 

Department of Fish and Wildlife. Salem, OR. 372 pp. 

Olson, B.E. 1999. Impacts of noxious weeds on ecologic and economic systems. In: R.L. Sheley and 

J.K. Petroff, eds. Biology and management of noxious rangeland weeds. Corvallis, OR: 

Oregon State University Press. 

Page, G.W., L.E. Stenzel, and C.A. Ribic. 1985. Nest site selection and clutch predation in the snowy 

plover. Auk 32:347-353. 

Page, G.W., J.S. Warriner, J.C. Warriner, and P.W.C. Paton. 1995. Snowy plover (Charadrius 

alexandrines). No. 154 in: A. Poole and F. Gill, eds. The birds of North America. The 

Academy of Natural Sciences, Philadelphia, PA, and the American Ornithologists’ Union, 

Washington, D.C. 

Page, G.W., L.E. Stenzel, and J.E. Kjelmyr. 1999. Overview of shorebird abundance and distribution 

in wetlands of the Pacific Coast of the contiguous United States. Condor 101:461-471. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-50 Chapter 4. Biological Environment 

Pampush, G.J. and R.G. Anthony. 1993. Nest success, habitat utilization and nest-site selection of 

long-billed curlews in the Columbia Basin, Oregon. Condor 95:957-967. 

Paton, W.C. and J. Dalton. 1994. Breeding ecology of long-billed curlews at Salt Lake, Utah. Great 

Basin Naturalist 54(1):79-85. 

Paullin, D.G., G.L. Ivey, and C.D. Littlefield. 1988. The re-establishment of American white pelican 

nesting in the Malheur-Harney Lakes Basin, Oregon. Murrelet 69:61-64. 

Paullin, D.G., C.D. Littlefield, and R.E. Vorderstrasse. 1977. Malheur-Harney Lakes Basin study, 

Oregon. Report no. 1: a summary of biological data for calendar years 1975 and 1976. U.S. 

Fish and Wildlife Service. Portland, OR. 

Raleigh, R.F., L.D. Zuckerman, and P.C. Nelson. 1984. Habitat suitability index models and instream 

flow suitability curves: brown trout. FWS/OBS-SZ/10.7 1. U.S. Fish and Wildlife Service 

Biological Services Program. 

Raven, C. and R.G. Elston, eds. 1992. Land and life at Malheur Lake: preliminary geomorphological 

and archaeological investigations. Intermountain Research. Silver City, Nevada. 

Reynolds, T.D., T.D. Rich, and D.A. Stephens. 1999. Sage thrasher (Oreoscoptes montanus). No. 

463 in: A. Poole and F. Gill, eds. The birds of North America. The Academy of Natural 

Sciences, Philadelphia, PA, and the American Ornithologists’ Union, Washington, D.C. 

Salant, N., J.C. Schmidt, P.R. Wilcock, and P.E. Budy. 2010. Geomorphic history and current 

channel condition of the Donner und Blitzen River, Malheur National Wildlife Refuge, 

Oregon. Technical report. Utah State University. Logan, UT. 82 pp. 

Sedgwick, J.A. 2000. Willow flycatcher (Empidonax traillii). No. 533 in: A. Poole and F. Gill, eds. 

The birds of North America. The Academy of Natural Sciences, Philadelphia, PA, and the 

American Ornithologists’ Union, Washington, D.C. 

Shaw, S.P., and C.G. Fredine. 1956. Wetlands of the United States. Circular 39. USDI, Fish and 

Wildlife Service. Washington, D.C. 67 pp. 

Sousa, P.J. 1985. Habitat suitability index models: gadwall (breeding). Biological report 82(10.100). 

U.S. Department of the Interior, Fish and Wildlife Service. Washington, D.C. 35 pp. 

Spencer, S.V. 1994. Recovery of marsh vegetation at Malheur Lake following an extended flood. 

Portland State University. Portland, OR. 

Stiehl, R.B. 1976. An ecological study of the common raven (Corvus corax) at Malheur NWR and its 

effects on the nesting success of selected waterfowl. Ph.D. dissertation. Portland State 

University, Portland, OR. 

Stiehl, R.B. 1985. Brood chronology of the common raven. Wilson Bulletin 97:78-87. 

Stiehl, R.B. and S.N. Trautwein. 1991. Variations in diets of nesting common ravens. Wilson 

Bulletin 103:83-92. 

Stone, K.R. 2009. Grus canadensis. In: Fire effects information, U.S. Department of Agriculture, 

Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. Available at: 

http://www.fs.fed.us/database/feis/. Accessed January 2010. 

Summerfelt, R.C., J.C. Bartonek, R.N. Denny, H. Duebbert, L. Hubbard, G. Swanson, R.J. Vogl, and 

M.W. Weller. 1980. Future management of Malheur Lake marsh: recommendations of the 

technical advisory committee. Unpublished report. Malheur National Wildlife Refuge. 

Princeton, OR. 126 pp. 

Tacha, T.C., S.A. Nesbitt, and P.A. Vohs. 1992. Sandhill crane (Grus canadensis). No. 31 in: A. 

Poole and F. Gill, eds. The birds of North America. The Academy of Natural Sciences, 

Philadelphia, PA, and the American Ornithologists’ Union, Washington, D.C. 

Taylor, D.T. 1986. Effects of cattle grazing on passerine birds nesting in riparian habitat. Journal of 

Range Management 39:254-258. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

Chapter 4. Biological Environment 4-51 

Thompson, S.P., R.S. Johnstone, and C.D. Littlefield. 1982. Nesting history of golden eagles in 

Malheur-Harney Lakes Basin, southeastern Oregon. Journal of Raptor Research 16(4):116-

122. 

Thompson, S.P., C.D. Littlefield, and R.A. Ryder. 1979. Historical review and status of colonial 

nesting birds on Malheur National Wildlife Refuge, Oregon. Proceedings of the Colonial 

Waterbird Group 3:156-164. 

Thorne, T.D. and P.S. Zwauk. Foods of migrating cinnamon teal in Central New Mexico. Journal of 

Field Ornithology 64(4):452-463. 

Twedt, D.J. and R.D. Crawford. 1995. Yellow-headed blackbird (Xanthocephalus xanthocephalus). 

No. 31 in: A. Poole and F. Gill, eds. The birds of North America. The Academy of Natural 

Sciences, Philadelphia, PA, and the American Ornithologists’ Union, Washington, D.C. 

USFWS (U.S. Fish and Wildlife Service). 1990. Blitzen Valley management plan, Malheur National 

Wildlife Refuge. Princeton, OR 

USFWS. 1991. Stephanomeria malheurensis (Malheur wirelettuce) recovery plan. Portland, OR. 34 

pp. 

USFWS. 2008a. Identifying resources of concern and management priorities for a refuge: a 

handbook (draft version). Washington, D.C. 

USFWS. 2008b. Yellow-billed cuckoo. Available at: 

http://www.fws.gov/oregonfwo/species/data/yellowbilledcuckoo/. 

Wigand, P.E. 1987. Diamond Pond, Harney County, Oregon: vegetation history and water table in 

the eastern Oregon desert. Great Basin Naturalist 47(3):427-458. 

Wittenberger, J.F. 1978. The breeding biology of an isolated bobolink population in Oregon USA. 

Condor 80:355-371. 

Woodin, M.C. and T.C. Michot. 2002. Redhead (Aythya americana). No. 695 in: A. Poole and F. 

Gill, eds. The birds of North America. The Academy of Natural Sciences, Philadelphia, PA, 

and the American Ornithologists’ Union, Washington, D.C. 

Young, R.P. 1986. Fire ecology and management in plant communities of Malheur National Wildlife 

Refuge southeastern Oregon. Ph.D. dissertation. Oregon State University, Corvallis. 

Zoellick, B.W. and B.S. Cade. 2006. Evaluating redband trout habitat in sagebrush desert basins in 

southwestern Idaho. North American Journal of Fisheries Management 26(2):268-281. 
Malheur National Wildlife Refuge Comprehensive Conservation Plan 

4-52 Chapter 4. Biological Environment 

This page left blank intentionally.