TEETERING ON THE EDGE OR TOO LATE? CONSERVATION … · the total area managed by the U.S. Department of Energy, 20% (3.6 million ha) of the total area managed by the U.S. Fish and

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TEETERING ON THE EDGE OR TOO LATE? CONSERVATIONAND RESEARCH ISSUES FOR AVIFAUNA OF SAGEBRUSHHABITATSAuthors: Steven T. Knick, David S. Dobkin, John T. Rotenberry, Michael A.Schroeder, W. Matthew Vander Haegen, et. al.Source: The Condor, 105(4) : 611-634Published By: American Ornithological SocietyURL: https://doi.org/10.1650/7329

Downloaded From: https://bioone.org/journals/The-Condor on 18 Jul 2019Terms of Use: https://bioone.org/terms-of-use

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ISSUES IN CONSERVATION

The Condor 105:611–634q The Cooper Ornithological Society 2003

TEETERING ON THE EDGE OR TOO LATE? CONSERVATION ANDRESEARCH ISSUES FOR AVIFAUNA OF SAGEBRUSH HABITATS

STEVEN T. KNICK1,7, DAVID S. DOBKIN2, JOHN T. ROTENBERRY3, MICHAEL A. SCHROEDER4,W. MATTHEW VANDER HAEGEN5 AND CHARLES VAN RIPER III6

1USGS Forest and Rangeland Ecosystem Science Center, Snake River Field Station,970 Lusk Street, Boise, ID 83706

2High Desert Ecological Research Institute, 15 S.W. Colorado Ave., Suite 300, Bend, OR 977023Center for Conservation Biology and Department of Biology, University of California, Riverside, CA 92521

4Washington Department of Fish and Wildlife, P.O. Box 1077, Bridgeport, WA 988135Washington Department of Fish and Wildlife, 600 North Capitol Way, Olympia, WA 98501

6USGS Southwest Biological Science Center, Northern Arizona University,P.O. Box 5614, Bldg. 24, Flagstaff, AZ 86011

Abstract. Degradation, fragmentation, and loss of native sagebrush (Artemisia spp.) land-scapes have imperiled these habitats and their associated avifauna. Historically, this vastpiece of the Western landscape has been undervalued: even though more than 70% of allremaining sagebrush habitat in the United States is publicly owned, ,3% of it is protectedas federal reserves or national parks. We review the threats facing birds in sagebrush habitatsto emphasize the urgency for conservation and research actions, and synthesize existinginformation that forms the foundation for recommended research directions. Managementand conservation of birds in sagebrush habitats will require more research into four majortopics: (1) identification of primary land-use practices and their influence on sagebrushhabitats and birds, (2) better understanding of bird responses to habitat components anddisturbance processes of sagebrush ecosystems, (3) improved hierarchical designs for sur-veying and monitoring programs, and (4) linking bird movements and population changesduring migration and wintering periods to dynamics on the sagebrush breeding grounds.This research is essential because we already have seen that sagebrush habitats can be alteredby land use, spread of invasive plants, and disrupted disturbance regimes beyond a thresholdat which natural recovery is unlikely. Research on these issues should be instituted on landsmanaged by state or federal agencies because most lands still dominated by sagebrush areowned publicly. In addition to the challenge of understanding shrubsteppe bird-habitat dy-namics, conservation of sagebrush landscapes depends on our ability to recognize and com-municate their intrinsic value and on our resolve to conserve them.

Key words: Artemisia, conservation, landscape change, land use, priority research is-sues, sagebrush ecosystems, shrubland loss.

¿Tambaleando en el Borde o Demasiado Tarde? Asuntos de Conservacion e Investigacionpara la Avifauna de Ambientes de Matorral de Artemisia spp.

Resumen. La degradacion, fragmentacion y perdida de paisajes nativos de matorrales deArtemisia spp. han puesto en peligro a estos ambientes y su avifauna asociada. Historica-mente, esta vasta porcion del paisaje occidental ha sido subvalorada: aunque mas del 70%de todo el habitat de matorral de Artemisia de los Estados Unidos es de propiedad publica,

Report of the Cooper Ornithological Society Committee for Conservation of Sagebrush Ecosystems.Received 4 April 2003; accepted 4 August 2003.7 E-mail: [email protected]


612 STEVEN T. KNICK ET AL.

,3% de este es protegido por reservas federales o parques nacionales. En este artıculorevisamos las amenazas a las que se enfrentan las aves de los matorrales de Artemisia paraenfatizar la urgencia de emprender acciones de conservacion e investigacion, y sintetizamosla informacion existente que constituye la base para una serie de directrices de investigacionrecomendadas. El manejo y conservacion de las aves de los matorrales de Artemisia nece-sitara mas investigacion en cuatro topicos principales: (1) la identificacion de practicasprimarias de uso del suelo y su influencia sobre los ambientes y las aves de Artemisia, (2)un mejor entendimiento de las respuestas de las aves a componentes del habitat y a procesosde disturbio de los ecosistemas de Artemisia, (3) el mejoramiento de disenos jerarquicospara programas de censos y monitoreos y (4) la conexion de los movimientos de las avesy los cambios poblacionales durante la migracion y en los perıodos de invernada con ladinamica en las areas reproductivas de matorrales de Artemisia. Estas investigaciones sonesenciales porque ya hemos visto que los ambientes de Artemisia pueden ser alterados porel uso del suelo, la diseminacion de plantas invasoras y la disrupcion de los regımenes dedisturbio mas alla de un umbral en el que la recuperacion natural es poco probable. Lainvestigacion en estos asuntos debe instituirse en tierras manejadas por agencias estatales ofederales porque la mayorıa de las tierras aun dominadas por Artemisia son de propiedadpublica. Ademas del desafıo de entender la dinamica aves-habitat en las estepas arbustivas,la conservacion de los paisajes de matorral de Artemisia depende de nuestra habilidad dereconocer y comunicar su valor intrınseco y de nuestra decision para conservarlos.

INTRODUCTION

The increasingly rapid and widespread degra-dation, fragmentation, or total loss of sagebrush(Artemisia spp.) ecosystems throughout westernNorth America presents a grave challenge tonatural-resource agencies charged with theirmanagement and restoration. Sagebrush oncecovered roughly 63 million ha in western NorthAmerica, but very little now exists undisturbedor unaltered from its condition prior to Eurasiansettlement (West 1996, Miller and Eddleman2001). Perhaps 50–60% of the native sagebrushsteppe now has either exotic annual grasses inthe understory or has been converted completelyto non-native annual grasslands (West 2000).Sagebrush habitats are among the most imper-iled ecosystems in North America (Noss and Pe-ters 1995, Mac et al. 1998).

Human activities have caused most of the lossof sagebrush (West and Young 2000). Landmanagers have used prescribed fires, mechanicaltreatments (including shredding, roller chopping,hand slashing, bulldozing, beating, chaining,root plowing, and disk plowing), biologicalagents, and herbicides to remove sagebrush fromlarge areas for reseeding with non-native grass-es, principally to provide forage for livestock(Pechanec et al. 1965, Vale 1974, Bureau ofLand Management 1991). Agriculture, mining,oil, gas, and coal-bed methane development, po-werline and natural-gas corridors, urbanization,and expansion of road networks have fragment-ed landscapes or completely eliminated sage-brush from extensive areas (Noss et al. 1995,

Hann et al. 1997). Other activities, such as live-stock grazing, have facilitated the spread of in-vasive plant species, intensified wildfires, and al-tered disturbance regimes through indirect butoften synergistic effects on vegetation commu-nities and soils (Mack 1981, d’Antonio and Vi-tousek 1992, Brooks and Pyke 2001). Thesechanges have pushed many sagebrush systemsbeyond thresholds from which recovery to a pre-Eurasian-settlement condition is unlikely (Lay-cock 1991, West and Young 2000). The cumu-lative effects of land use and habitat degradationraise the greater threat of imminent large-scalecollapses of sagebrush ecosystems.

Loss of sagebrush habitats and concern forsagebrush-dependent birds were detailed over aquarter of a century ago by the ConservationCommittee of the Wilson Ornithological Society(Braun et al. 1976). Since then, numbers ofsage-grouse (Centrocercus spp.) have continuedto decline throughout their range (Connelly andBraun 1997, Braun 1998, Connelly, Schroeder,et al. 2000) and individual populations have be-come increasingly separated (Schroeder, Hays,Livingston, et al. 2000, Beck et al. 2003). TheGunnison Sage-Grouse (C. minimus) has candi-date status for federal listing as a threatened orendangered species (U.S. Fish and Wildlife Ser-vice 2000). As of March 2003, four petitions forsubpopulations and one rangewide petition hadbeen filed to list Greater Sage-Grouse (C. urop-hasianus). Columbian Sharp-tailed Grouse(Tympanuchus phasianellus columbianus) alsohave declined dramatically and now exist onlyin small, isolated populations (McDonald and


BIRDS IN SAGEBRUSH ECOSYSTEMS 613

TABLE 1. Sagebrush area and management responsibility by ecoregions (Nature Conservancy 2001) in thewestern United States. We included only those ecoregions in which .1% of the total land area was in sagebrushcovera, as measured from current distribution (Comer et al. 2002).

EcoregionTotal area

(ha)

Sagebrush areaa

(ha) (% of totalarea)

Management responsibilityb

% total area (% sagebrush area)

Private

Public

BLM

Otherfederalagencyc State

Wyoming BasinsColumbia PlateauGreat BasinUtah High PlateausUtah-Wyoming Rocky Mtns.

13 365 54429 145 80929 304 818

4 590 54810 952 783

7 366 521 (55)14 064 004 (48)

8 844 892 (30)816 128 (18)

1 825 576 (17)

34 (30)45 (23)16 (13)21 (27)22 (34)

51 (56)41 (60)62 (70)35 (31)

7 (16)

8 (8)9 (12)

17 (17)37 (33)66 (43)

6 (7)4 (5)2 (1)7 (9)3 (6)

Middle RockiesModoc PlateauSouthern Rocky Mtns.Northern Great Plains SteppeColorado Plateau

21 420 2215 813 901

16 165 71764 234 60419 648 973

3 389 493 (16)589 075 (10)

1 389 004 (9)3 290 725 (5)

841 092 (4)

33 (34)29 (24)37 (51)73 (67)15 (20)

10 (36)7 (28)

11 (28)11 (21)31 (60)

52 (24)60 (43)48 (15)

8 (4)47 (11)

4 (6)3 (5)4 (6)7 (8)7 (8)

OkanoganSierra NevadaRemaining ecoregionsd

Totals

8 842 5645 017 618

73 159 711314 712 432

288 010 (3)71 916 (1)82 486 (,1)

43 099 867 (14)

31 (55)7 (35)

56 (80)37 (28)

1 (6)5 (7)2 (,1)

24 (52)

9 (25)87 (54)36 (15)32 (15)

7 (14)1 (3)6 (6)6 (5)

a Sagebrush communities include Wyoming and Basin big sagebrush, black sagebrush, low sagebrush, lowsagebrush–mountain big sagebrush, low sagebrush–Wyoming big sagebrush, mountain big sagebrush, scablandsagebrush, threetip sagebrush, Wyoming big sagebrush, and Wyoming big sagebrush–squaw apple.

b GIS maps of land ownership and management authority were developed from individual state coverages.c Includes the following U.S. agencies: Fish and Wildlife Service, Bureau of Indian Affairs, National Park

Service, Department of Energy, Department of Agriculture, and Department of Defense.d Includes Black Hills, Canadian Rocky Mountains, Central Shortgrass Prairie, Fescue-Mixed Grass Prairie,

Klamath Mountains, and West Cascades.

Reese 1998, Schroeder, Hays, Murphy, andPierce 2000). Other taxa dependent on sage-brush also are declining: the Columbia Basinpopulation of pygmy rabbits (Brachylagus ida-hoensis) was listed under the Endangered Spe-cies Act in March 2003 (U.S. Fish and WildlifeService 2003).

Shrubland and grassland birds are decliningfaster than any other group of species in NorthAmerica (Dobkin 1994, Saab and Rich 1997,Paige and Ritter 1999). These species representan important component of the biodiversity ofthe western United States, but have seen littleconservation action until recently. Now, Bre-wer’s Sparrow (Spizella breweri), Sage Sparrow(Amphispiza belli), and Sage Thrasher (Oreos-coptes montanus), the three primary passerinespecies of sagebrush habitats, receive specialconservation status in one or more western states(Knick and Rotenberry 2002). In addition, thesebirds may be important predictors of impendingcollapse in sagebrush ecosystems because oftheir sensitivity to multiscale habitat changes

(Rotenberry and Knick 1999, Knick and Roten-berry 2000).

Conservation and restoration of sagebrushlands now are top priorities of natural-resourceagencies (Bureau of Land Management 2002a).This recent emphasis may represent changing at-titudes about the intrinsic value of sagebrushecosystems, or it may be a reaction to the threatof petitions to list species under the EndangeredSpecies Act. If the Greater Sage-Grouse or anyof the other species living in sagebrush ecosys-tems were to be listed, there would be majorramifications for use and management of largeareas of the western United States. Approxi-mately 30% (22.4 million ha) of the total areain the lower 48 states managed by the U.S. Bu-reau of Land Management, 50% (300 000 ha) ofthe total area managed by the U.S. Departmentof Energy, 20% (3.6 million ha) of the total areamanaged by the U.S. Fish and Wildlife Service,and 11.5% (2.1 million ha) of the total area man-aged by state agencies is sagebrush habitats (Ta-ble 1). Less than 3% of the area dominated by



sagebrush lies within national parks or wilder-ness areas that receive permanent legal protec-tion from conversion of land cover (Scott, Mur-ray, et al. 2001, Wright et al. 2001). From a con-servation perspective, these reserves provideneither the geographic distribution nor at least10% of their total area estimated to be necessaryfor long-term species conservation (Scott, Davis,et al. 2001). Less than 30% of all sagebrushlands are owned privately. Consequently, the fu-ture of sagebrush ecosystems will be affectedprimarily by use of public lands and policies ofthe management agencies (Raphael et al. 2001).

Here, we identify priority research issuesneeded for conservation of birds in sagebrushecosystems in western North America. We alsoreview and synthesize existing information pro-viding the foundation for these issues. We beginby documenting the numerous impacts contrib-uting to loss and degradation of sagebrush hab-itats across their widespread distribution. Suchdocumentation is critical if we are to implementscience-based policies to conserve these ecosys-tems under increasing demand for their resourc-es.

The primary research issues that we presentwere developed to (1) understand the impacts ofland-use practices on sagebrush habitats andbirds; (2) examine relationships between birdsand habitat characteristics; (3) identify popula-tion trends, distribution, and abundance; and (4)link our understanding of breeding-ground dy-namics with those encountered during migrationand on wintering grounds. These issues origi-nated at a multiagency workshop held in August2001 in Boise, Idaho. The different missions ofthe agencies and individuals involved (see Ac-knowledgments) reflect varying applications, butwith a common need for improved informationon birds living in sagebrush habitats.

THE SAGEBRUSH REGION

Our review focused on shrublands dominated bysagebrush in the western United States (Fig. 1).Unless otherwise indicated, statistics were de-rived for 13 ecoregions (Nature Conservancy2001) in 14 states, in which .1% of land surfacewas sagebrush cover. Data presented by statesinclude California, Colorado, Idaho, Montana,Nevada, Oregon, Utah, Washington, and Wyo-ming. States having limited geographic distri-bution of sagebrush (Nebraska, North Dakota,South Dakota) or for which reliable maps of

sagebrush distribution were not available (Ari-zona, New Mexico) were excluded from statesummaries.

Woody species of sagebrush are divided intotall and low groups (Miller and Eddleman 2001,West and Young 2000). Three subspecies withinthe tall sagebrush group, Wyoming big sage-brush (Artemisia tridentata ssp. wyomingensis),basin big sagebrush (A. t. ssp. tridentata), andmountain big sagebrush (A. t. ssp. vaseyana), aremost widely distributed (McArthur 1994). Lowsagebrush (A. arbuscula) and black sagebrush(A. nova) are the primary species in the lowsagebrush groups. With the exception of re-search on sage-grouse, most bird-focused studieshave lumped the Artemisia groups and species,even though site characteristics, ecological re-lationships, and response to disturbance varywidely (McArthur 1994, Miller and Eddleman2001).

We conducted spatial analyses on a base mapof sagebrush distribution (Comer et al. 2002).Land ownership and management-authority sta-tistics were obtained by combining individualstate coverages. All GIS coverages used in ouranalyses can be downloaded from the SAGE-MAP website (U.S. Geological Survey 2001).

We emphasized birds that use sagebrush astheir primary habitat. However, we recognizethat specialized habitats within sagebrush land-scapes, such as riparian and wetland areas, pro-vide critical resources for many other birds(Dobkin et al. 1995, 1998, Haig et al. 1998,Warnock et al. 1998).

CURRENT CHALLENGES TOCONSERVING SAGEBRUSHECOSYSTEMS

EFFECTS OF LAND-USE PRACTICES

Past and current uses of public lands have im-pacted virtually all sagebrush ecosystems (Bocket al. 1993, West and Young 2000, Miller andEddleman 2001). Livestock grazing, conversionto agriculture or urban areas, energy and naturalresource development, habitat treatment, andeven restoration activities, have had direct aswell as indirect consequences. The magnitude ofthese effects is difficult to quantify. Direct ef-fects, such as extent of fragmentation or totalarea lost, rarely have been linked to specific landuses (Dobler et al. 1996, Hann et al. 1997, Knickand Rotenberry 1997) and cumulative effects



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have not been estimated over the large geo-graphic extent of sagebrush. These analyseshave been hindered because large-scale mapshave been unavailable, inconsistent across ad-ministrative boundaries, or limited by coarsespatial and thematic resolution. Similarly, an as-sessment of landscape changes caused by landuse has been precluded by lack of maps depict-ing habitats at comparable resolutions to contrastdifferent times.

Other effects, such as altered or depleted un-derstories, have been well documented in localsite-specific contexts but are difficult to quantifyfor large areas because of our inability to trans-late local events into broad-scale dynamics (Al-len and Starr 1982, Wiens 1989a). Technologicalchallenges also limit mapping these conditionsin semiarid regions using remote sensing (Knicket al. 1997). As a result, the wide geographicdistribution of sagebrush in maps depicting onlya dominant cover type (Fig. 1) provides a de-ceptive mask and false sense of security. Landuses influence site-specific factors as well aslandscape features to form a complex mosaic ofvaried conditions and histories. Thus, analysesof additional landscape metrics, such as frag-mentation (Fig. 2), may be necessary to identifythe potential consequences for disturbance re-gimes, invasions of exotic plants, and trajecto-ries of future vegetation dynamics (Turner et al.2001).

LIVESTOCK GRAZING

Livestock grazing and associated habitat alter-ations have had the most widespread impact onwestern ecosystems of any land use (Bock et al.1993, Fleischner 1994). Virtually all sagebrushlands are managed principally for livestock graz-ing. In 2001, 15 000 permits were issued for.10.2 million animal unit months of forage con-sumption on lands managed by the U.S. Bureauof Land Management (Bureau of Land Manage-ment 2002b). (One animal unit month 5 thequantity of forage required by 1 mature cowweighing 454 kg and calf, or equivalent, for 1month.) Livestock grazing can change habitatfeatures that directly influence birds; for exam-ple, by reducing plant species diversity and bio-mass (Reynolds and Trost 1981, Bock and Webb1984, Saab et al. 1995). Alternatively, changesin water and nutrient cycling caused by grazingcan promote the spread of invasive species,which then degrade native bird habitats by al-

tering fire and disturbance regimes (Rotenberry1998). In addition, activities associated withlivestock production, such as feedlots, can facil-itate nest predators or parasitism by Brown-headed Cowbirds (Molothrus ater; Vander Hae-gen and Walker 1999, Goguen and Matthews2000).

Many areas of sagebrush steppe in westernNorth America historically did not support herdsof large ungulates. Large native herbivores haddisappeared by 12 000 years BP, and native veg-etation communities developed in the absence ofsignificant grazing pressure (Grayson 1994). Be-cause of semiarid climate and the absence ofgrazing in their recent evolutionary history,sagebrush systems are particularly sensitive tograzing disturbance (Mack and Thompson1982). Excessive grazing by domestic livestockduring the late 1800s and early 1900s, coupledwith severe drought, significantly impactedsagebrush ecosystems (Yensen 1981, Young andSparks 2002). Long-term effects persisting todayinclude widespread changes in plant communitycomposition and soils that have increased thespread of exotic vegetation and altered naturaldisturbance regimes (Yensen 1981, Young 1994,Miller and Rose 1999).

Manipulation of sagebrush landscapes to in-crease forage production for livestock has dom-inated our perspective and shaped our use ofsagebrush ecosystems (Holechek et al. 1998).Large expanses of sagebrush have been eradi-cated and reseeded with non-native grasses (pri-marily crested wheatgrass [Agropyron crista-tum]) to increase production of forage for live-stock grazing (Hull 1974, Evans and Young1978, Shane et al. 1983). An estimated 2–6 mil-lion ha of sagebrush lands were treated to reduceor eliminate sagebrush cover by the 1970s(Schneegas 1967, Vale 1974). Thinning or pre-scribed burning to reduce cover density of sage-brush and promote forb and grass productioncontinues to be practiced widely (Olson andWhitson 2002, Bureau of Land Management2002a, Wambolt et al. 2002).

AGRICULTURE AND URBANIZATION

Crop production on lands previously dominatedby sagebrush has completely converted vasttracts of sagebrush habitats and fragmentedmany remaining landscapes (Wisdom et al.2000; Fig. 3). Similarly, urbanization, roads, andpowerlines continue to fragment ecological sys-



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FIGURE 3. Agricultural lands in Washington, Oregon, and Idaho relative to large-scale patterns of sagebrushdistribution. Crop production has fragmented or completely converted many sagebrush landscapes throughoutthe West.

tems (Trombulak and Frissell 2000, Wright et al.2001). This loss represents a major challenge forrestoration (and may be irreversible) because es-sential components of the system are disruptedor lacking entirely.

Lands converted to agriculture occur primar-ily at low elevations in areas containing deep,highly productive soils (Dobler et al. 1996,Scott, Murray, et al. 2001). In central Washing-ton, 75% of the shrubsteppe regions containingloamy soils have been converted to agricultureor other land uses, compared to ,15% of theshrubsteppe communities on shallow soils (Van-der Haegen et al. 2000). An estimated 99% ofthe basin big sagebrush habitats in the SnakeRiver Plain now are used for cropland (Hironakaet al. 1983).

Development of the agricultural landscape hasfragmented sagebrush steppe regions at multiple

scales (Fig. 2, 3). Fragments of intact sagebrushhabitats in Washington now exist within a matrixof agriculture (Vander Haegen et al. 2001). Themean patch size of sagebrush in Washington de-creased from 13 420 ha to 3418 ha and the num-ber of patches increased from 267 to 370 be-tween 1900 and 1990 (Hann et al. 1997, Mc-Donald and Reese 1998). Nest predation also in-creased in fragmented habitats dominated byagriculture (Vander Haegen et al. 2002). Cow-bird parasitism increased in agricultural land-scapes and in the presence of feedlots for live-stock, although the rate of cowbird parasitism onshrubsteppe birds generally remains low (VanderHaegen and Walker 1999). At broader scales,conversion of the Snake River Plain to agricul-ture disconnected regions north of the SnakeRiver from sagebrush in southern Idaho andnorthern Nevada (Fig. 1, 3).



FIGURE 4. Existing oil and gas developments in Wyoming relative to large-scale patterns of sagebrush dis-tribution. Powerlines were buffered by 1.5 km to reflect the increased risk of predation by raptors and corvidson sage-grouse and other species.

NATURAL RESOURCE DEVELOPMENT

Approximately 2.7 million ha of western landsadministered by the U.S. Bureau of Land Man-agement currently are in production status foroil, gas, or geothermal energy (Bureau of LandManagement 2002b). An estimated 9.3 millionha in five basins of federal lands (includes hab-itats in addition to sagebrush) in Montana, Wy-oming, Colorado, Utah, and New Mexico, areavailable for oil and gas leasing with standardstipulations (U.S. Departments of Interior, Ag-riculture, and Energy 2003). Approval for29 000 new oil and gas leases is anticipated by2005 (Bureau of Land Management 2003).

Energy development and natural resource ex-traction directly alter sagebrush habitats at thesite of operation (Braun et al. 2002). In Wyo-ming, existing oil and gas wells were locatedprimarily in landscapes dominated by sagebrush

(Fig. 4). Associated road networks, pipelines,and powerline transmission corridors also influ-ence vegetation dynamics by fragmenting habi-tats or by creating soil conditions facilitating thespread of invasive species (Fig. 4; Braun 1998,Gelbard and Belnap 2003). Density of sage-brush-obligate birds within 100 m of roads con-structed for natural gas development in Wyo-ming was 50% lower than at greater distances(Ingelfinger 2001). Increased numbers of cor-vids and raptors associated with powerlines(Steenhof et al. 1993, Knight and Kawashima1993, Vander Haegen et al. 2002) also increasethe potential impact of predation on sage-grouseand other sagebrush-breeding birds.

HABITAT TREATMENT

Land managers burn or otherwise treat large ar-eas of sagebrush habitats on public lands every



year. In 2000 and 2001, prescribed fires wereused to treat 50 000 ha managed by the Bureauof Land Management; nonfire treatments (e.g.,herbicides, biocontrols, mechanical alteration)were used on an additional 96 000 ha (Bureauof Land Management 2001, 2002b). The pre-ferred alternative presented by the Bureau ofLand Management in the Final Vegetation En-vironmental Impact Statement (Bureau of LandManagement 1991) recommended treating919 212 ha in the 13 western states annually.The appropriateness of these actions and theireffects on habitats and the associated avifaunaare widely debated (Connelly, Reese, et al. 2000,Wambolt et al. 2002).

Prescribed fire, herbicides, and numerous me-chanical and biological means are used to thinor reduce biomass of woody vegetation, improveforage production for livestock, control invasiveweeds or insects, or obtain a desired seral con-dition. Our understanding of the effects of thesehabitat treatments on diversity, density, or pro-ductivity of shrubland birds most often has beenderived from studies of specific, fine-scale man-agement actions (Best 1972, Schroeder and Stur-ges 1975, Castrale 1982, Petersen and Best1987, Howe et al. 1996). With few exceptions(Kerley and Anderson 1995), most studies ad-dress short-term effects immediately post-treat-ment. Of 35 papers investigating perturbation ef-fects, 94% did not sample pretreatment condi-tions, had no controls, or were of short duration(Petersen and Best 1999). Planned experimentsthat incorporate habitat manipulations are rare(Wiens and Rotenberry 1985, Winter and Best1985, Wiens et al. 1986, Fischer et al. 1997,Connelly, Reese, et al. 2000) but provide greaterinsights into mechanisms underlying habitatchange and bird response.

EXOTIC PLANTS IN SAGEBRUSHECOSYSTEMS

Exotic plant species, such as cheatgrass (Bromustectorum), yellow starthistle (Centaurea solsti-tialis), spotted knapweed (C. biebersteinii [5maculosa]), tamarisk (Tamarix ramosissima),medusahead wildrye (Taeniatherum caput-me-dusae), and rush skeleton-weed (Chondrilla jun-cea), are rapidly invading breeding and winter-ing ranges of birds. Invasion of alien plantscauses changes in the vegetation compositionand structure and alters disturbance regimes(Brooks and Pyke 2001). The area infested by

exotic plants increased from 1.1 million ha in1985 to 3.2 million ha in 1994 on lands managedby the Bureau of Land Management (Bureau ofLand Management 1996). Rate of spread fornoxious weeds has been estimated to be approx-imately 931 ha day21 on BLM lands and 1862ha day21 on all public lands in the West (Bureauof Land Management 1996).

SAGEBRUSH REHABILITATION ANDRESTORATION

The accelerating frequency of large wildfires insagebrush ecosystems has resulted in extensiverehabilitation efforts to control erosion, returnstability to the system and, in some cases, re-establish a shrubland landscape (Roundy et al.1995). During 2000–2001, $91 million was ap-proved to treat 755 000 ha of lands managed bythe Bureau of Land Management in the emer-gency fire rehabilitation program, whose pri-mary objective is to stabilize soils (Bureau ofLand Management 2001, 2002b). Federal agen-cies encourage the use of native seeds (Richardset al. 1998), but in reality the use of non-nativegrasses (such as crested wheatgrass) will contin-ue to increase because of the demand caused bylarge fires coupled with low availability of na-tive seeds from commercial seed sources (Asayet al. 2001). The effects of non-native grasseson dynamics of birds in sagebrush communitieshave not been well studied (Reynolds and Trost1981, McAdoo et al. 1989), particularly in thecontext of the landscape in which the rehabili-tation project is embedded.

Land-management agencies are developingmajor programs for restoration of sagebrush eco-systems (Beever and Pyke 2002, Bureau of LandManagement 2002a). Restoration will be diffi-cult, expensive, and may require decades oreven centuries (U.S. Department of Interior1996, Hemstrom et al. 2002). The process ofrecovery is relatively unknown, although wehave extensive documentation of deterioration insagebrush ecosystems (Allen-Diaz and Bartolo-me 1998). Not all areas previously dominated bysagebrush can be restored because alteration ofvegetation, nutrient cycles, topsoil, cryptobioticcrusts, and disturbance processes have pushedthese systems past critical thresholds from whichrecovery is unlikely (Allen 1988, Belnap andLange 2001, McIver and Starr 2001) or becausewe lack the political agenda and economic in-centives (Allen and Jackson 1992).



BIRD RESPONSE TO HABITAT CHANGES

Changes in composition and configuration ofsagebrush habitats from land use influence tem-poral dynamics such as disturbance or succes-sional pathways. These spatial and temporalcomponents of sagebrush ecosystems form theenvironmental template on which birds respond(Rotenberry and Wiens 1980a, 1980b, Roten-berry et al. 1995, Rotenberry and Knick 1999,Knick and Rotenberry 2000). Therefore, ourability to identify those habitat components andlink them to mechanisms of bird populationchange is critical to developing land-manage-ment and conservation plans (Morrison 2001,Noon and Franklin 2002, Wiens 2002).

LIFE-HISTORY ATTRIBUTES OF BIRDS INSAGEBRUSH HABITATS

Sagebrush ecosystems support few bird speciescompared to other ecosystems due to relativelylow floristic structure and diversity coupled withlow productivity and seasonal environments(Rotenberry 1998, Vander Haegen et al. 2001).Perhaps 18 bird species associated with sage-brush ecosystems are of conservation concern(Appendix; Paige and Ritter 1999). Our under-standing of bird and habitat relationships insagebrush systems, however, is based largely onstudies of three game species (Greater Sage-Grouse, Gunnison Sage-Grouse, Sharp-tailedGrouse) and three passerines (Sage Thrasher,Brewer’s Sparrow, Sage Sparrow). We know lit-tle basic life history of other bird species thatuse sagebrush habitats.

BIRD-HABITAT RELATIONSHIPS

The relationship of vegetation characteristics tobird distribution and abundance has been themost widely investigated aspect of birds asso-ciated with sagebrush habitats (Rotenberry andWiens 1978, Wiens and Rotenberry 1981, Ro-tenberry 1985, Wiens et al. 1987, Schroeder etal. 1999, Connelly, Schroeder, et al. 2000, Van-der Haegen et al. 2000). Most studies of birdand habitat relationships have been site specific.However, additional insights into compositionand disturbances structuring habitats used byshrubsteppe birds might be obtained from ameta-analysis of multiple sites. For example, weused data collected in Oregon, Nevada, Idaho,and Washington (Rotenberry and Wiens 1980b,Wiens and Rotenberry 1981, Dobler 1994,Knick and Rotenberry 1995) in a detrended cor-

respondence analysis to determine the primaryhabitat and disturbance gradients along whichshrubsteppe birds were distributed (Fig. 5). Thefirst axis captured the primary distribution ofbird species along a gradient from grassland toshrubland. We inferred an increasing fire fre-quency associated with greater amounts ofgrassland. The second axis contrasted a vegeta-tively open to dense habitat structure, which re-sulted from increasing likelihood of invasion byjuniper and other woody vegetation correlated inpart with decreasing fire frequency. By devel-oping models of bird and habitat relationships atmultiple scales of investigation, we can attemptto understand and predict the response ofshrubsteppe bird communities to habitat chang-es.

Statistical models used to derive relationshipsbetween animals and their habitats may fit a highproportion of the variation in the sample (Verneret al. 1986, Morrison 2001, Scott et al. 2002),but often these models do not perform well inregions or times outside of the sampling space(Rotenberry 1986, Knick and Rotenberry 1998).We may need to develop a different paradigm inthe way we assess habitats. Instead of derivinghabitat characteristics that are highly correlatedwith bird abundance, we might seek to identifya minimum or constant set of habitat character-istics required by a species to be present (Knopfet al. 1990). By modeling basic or minimum re-quirements, we may develop a better under-standing of components necessary to maintainbird populations, as well as improve capabilityto predict response of populations to habitatchanges (Rotenberry et al. 2002).

SCALES OF BIRD-HABITAT RELATIONSHIPS

Most research on response to habitat change bybirds, conducted at fine spatial and temporalscales, suggests that cumulative effects of localchanges significantly influence population dy-namics of birds in sagebrush habitats. Site-spe-cific studies have provided a good understandingof components of sagebrush habitats associatedwith breeding birds. However, we recently havenoted the relationship between landscape-levelhabitat variables and local abundances of birds(Knick and Rotenberry 1995, Knick and Roten-berry 1999, Vander Haegen et al. 2000). Occu-pancy of a home range is based on multiple var-iables operating at different scales: local vege-tation coupled with landscape characteristics



FIGURE 5. Primary habitat gradients along which birds in shrubland habitats are distributed. A detrendedcorrespondence analysis (DCA) was conducted on three geographically separate data sets containing similarhabitat variables from Oregon, Nevada, and Washington (Rotenberry and Wiens 1980b, Wiens and Rotenberry1981); Washington (Dobler 1994); and Idaho (Knick and Rotenberry 1995). Bird species are Gray Flycatcher(GRFL), Loggerhead Shrike (LOSH), Horned Lark (HOLA; Eremophila alpestris), Rock Wren (ROWR; Sal-pinctes obsoletus), Sage Thrasher (SATH), Green-tailed Towhee (GTTO), Brewer’s Sparrow (BRSP), VesperSparrow (VESP), Lark Sparrow (LASP), Black-throated Sparrow (BTSP), Sage Sparrow (SAGS), GrasshopperSparrow (GRSP; Ammodramus savannarum), and Western Meadowlark (WEME; Sturnella neglecta; see Ap-pendix for additional scientific names).

much larger than individual home ranges (Ro-tenberry and Knick 1999). The answer to howmuch habitat or how many resources are re-quired to sustain a population is not trivial anddiffers among species. Development of regionalvegetation maps (Comer et al. 2002) and GIS-based analyses should permit identification ofbroad-scale variables that affect species distri-bution. By integrating technological advancesand field research, we might better understandthe relative contribution of broad- and fine-scalehabitat features to dynamics of shrubland birds.

Historical information on long-term changesin bird distribution (Brown and Davis 1995)would improve our understanding of habitat re-lationships as well as increase our ability to pre-dict consequences of management decisions orglobal dynamics such as climate change. A long-term perspective of past fire regimes in sage-brush regions (Miller and Wigand 1994, Millerand Tausch 2001), coupled with vegetationchanges (Tausch 1999, Thompson and Anderson2000, Miller and Eddleman 2001), climate fluc-tuations, and anthropogenic impact, provide animportant context in which to interpret currentdynamics of sagebrush habitats and birds.

MECHANISMS OF BIRD RESPONSE TOHABITAT CHANGE

The processes by which birds respond to chang-es in habitat composition and configuration re-main elusive, and identifying them requiresknowledge of local population dynamics andtheir variations across the landscape (Knick andRotenberry 2002). Local abundance derivesfrom a complex interaction of habitat character-istics coupled with variation in survival, produc-tivity, and dispersal (Wiens 1989b, 1989c,2002). In sagebrush ecosystems, we do not un-derstand how habitat fragmentation influencesproductivity, density of breeding adults, size ofhome range, or probability of predation orBrown-headed Cowbird parasitism.

We lack the necessary demographic informa-tion to reliably model population growth and toascertain source-sink status for birds dependenton sagebrush habitats. Much of the focus of pro-ductivity studies for shrubsteppe passerines hasbeen on regional and annual variation (Roten-berry and Wiens 1989). Clutch size, nest suc-cess, and fledging rates vary significantly amongyears (Petersen and Best 1987, Rotenberry andWiens 1989) and may be related to weather be-



fore and during the nesting season (Rotenberryand Wiens 1991). More recently, the effect oflarge-scale habitat fragmentation on productivityof shrubland birds has been studied by integrat-ing satellite imagery with field studies in Wash-ington state, with the conclusion that nest suc-cess decreases in more-fragmented landscapes(Vander Haegen et al. 2002). Ultimately, criteriadefining source-sink habitat gradients need to bebased on measures of productivity per area oron population growth rates (Van Horne 1983,Morrison 2001, Misenhelter and Rotenberry2000).

RECOMMENDATIONS

We recommend research and management strat-egies based on the primary challenges to betterunderstand the effects of land use on sagebrushhabitats and to improve our knowledge of birdand habitat relationships. We strongly recom-mend integrated approaches that tier individualstudies into larger programs conducted over thelong term to address multiscale relationships.

EFFECTS OF LAND-USE PRACTICES

Accurate rangewide estimates of total area de-graded, fragmented, converted to agriculture, orinvaded by exotic weeds are needed to grasp ful-ly the magnitude of changes and their impact onbirds. For some pervasive land uses, such aslivestock grazing, empirical data to test the ef-fects on bird populations are limited (Bock andWebb 1984, Saab et al. 1995). We need experi-ments having strong statistical designs that in-clude treatments and controls at spatial and tem-poral scales relevant to the impacts to vegetationand soils and the dynamics of recovery (Fleisch-ner 1994, Tewksbury et al. 2002, Wambolt et al.2002). Long-term studies incorporating a wide-spread system of exclosures (Bock et al. 1993)and ability to control treatment levels are nec-essary to determine effects of land use on hab-itats and birds. The treatment projects plannedby management agencies and the large numberof areas to be treated represent a tremendous op-portunity to design a sound experimental ap-proach. In addition, a commitment to monitoringat appropriate scales would provide feedback toevaluate treatment effects and provide a basisfor adaptive management strategies (Walters1986, Morrison 2002).

Implementation of sound management basedon an understanding of the effects of land-use

practices, and enforced accountability to thosepolicies, may be the only way to ensure long-term survival of sagebrush habitats and theirbirds. Protection from economic use (as nationalparks or monuments) is not viable for all sage-brush lands but could be an option in specificareas that retain native plants or are importantregions for biodiversity. Purchasing lands forprotection (Shaffer et al. 2002) also is not acomplete solution because the areas required toencompass natural disturbance patterns are toolarge. Approximately 4.3 million ha of sage-brush lands would need to be placed in naturereserves if we are to meet the conservation goalof protecting 10% of the distribution. To developthis network of reserves, we need to prioritizethe landscape by identifying and providing pro-tection or other appropriate management tothose relatively large areas of sagebrush in goodcondition. We then need to enlarge existing pro-tected blocks, increase connectivity in the land-scape, and employ basic principles of landscapemanagement to ensure long-term survival ofsagebrush habitats and birds.

Complete restoration of habitats requires thatwe understand critical patterns and processes atthe appropriate spatial scales (Whisenant 1993).For sage-grouse, which may use ranges encom-passing .2500 km2 (Schroeder et al. 1999), cre-ating suitable habitats will require that we focusefforts to restore entire landscapes rather thanpursue individual unconnected efforts (Dobkin1995, Wisdom, Rowland, et al. 2002, Wisdom,Wales, et al. 2002). However, the ecologicalfoundation for development of overarching man-agement prescriptions based on sage-grouse(Dobkin 1995, Rich and Altman 2002) or othersingle-taxon approaches (such as birds) needs tobe tested for its capability to accommodate allspecies associated with sagebrush ecosystems.

In the absence of active restoration, exoticgrasses will continue to invade sagebrush land-scapes and degrade habitat (Hemstrom et al.2002, Wisdom, Rowland, et al. 2002). To coun-ter this disastrous scenario, we strongly recom-mend a federal policy to require use of ecolog-ically appropriate native plant species in allshrubsteppe restoration projects on public lands.Such a policy will provide the incentive for theprivate sector to create sufficient commercialsources of native seed. Mandatory use of nativeseed in public-land restoration is a relativelysimple step with great potential for redirecting



the ecological trajectory of these landscapesaway from ecological dysfunction and towardecological resiliency.

BIRD RESPONSE TO HABITAT CHANGE

Questions about basic life history for birds liv-ing in sagebrush habitats should form an inte-grated foundation for testing broader hypothesesabout relationships between birds and their hab-itats (Noon and Franklin 2002, Wiens 2002). Be-cause of their increasing dominance in sage-brush systems, we need to focus research on theinfluence of exotic plants on habitat dynamicsand bird response. Understanding mechanismsunderlying bird response to habitat characteris-tics will require that we determine populationinformation across a range of habitat conditions.We recommend establishing a coordinated net-work of study sites across a gradient of habitatconditions at which demographic information,such as reproductive success, adult and juvenilesurvival, adult return rates, and patterns of ju-venile dispersal, can be obtained. An intensiveprogram to mark birds at such sites could yieldgreat insight into population dynamics (Sherryand Holmes 2000) but will require a long-termcommitment to maintain. Long-term studies in-volving marked individuals also could assess thepotential for birds’ site fidelity to delay popu-lation response to habitat changes, a possiblecause of confounded bird-habitat models (Wienset al. 1986). Ultimately, development of popu-lation models based on life-stage informationcollected from such a network of sites (Caswell2001) could yield significant insights into criti-cal life stages, survival during breeding, migra-tion, and wintering periods, and the influence ofhabitat on population dynamics.

MONITORING AND SURVEY ISSUES

Robust sampling over spatial and temporalscales that we view as necessary must involvemethods that permit detectability estimates anddescribe sources of variation. Existing large-scale bird-monitoring programs, such as theNorth American Breeding Bird Survey (Robbinset al. 1986, Peterjohn and Sauer 1999) and theChristmas Bird Count (Root 1988) may not ad-equately sample many of the species in sage-brush ecosystems (Saab and Rich 1997). Thesesurveys also have come under increasing criti-cism because of their inability to estimate biasesin detectability of birds, which vary with respect

to species, observers, and vegetation type, andtheir subsequent failure to incorporate differen-tial detectabilities into trend analyses (Johnson1995, Anderson 2001). For some species, tar-geted surveys (i.e., lek counts for sage-grouse)and new methods may be required to estimatepopulation trends.

Almost all sampling of shrubsteppe bird pop-ulations has been based on counts of singingmales on survey plots. Yet, the relationship be-tween singing males and population parametershas not been established. Seasonal variation alsomay be critical in adjusting estimates based onlarge regions sampled throughout the breedingperiod (Best and Petersen 1985). Estimatesbased on counts of singing males may actuallyoverestimate the breeding segment of the pop-ulation by including nonbreeding territorialmales, confounding our conclusions about hab-itat associations or population trends.

Sampling effort of current monitoring pro-grams is distributed unevenly within sagebrushhabitats among individual states. Even thoughmany Breeding Bird Survey routes in westernstates sample sagebrush habitats, the proportionof sagebrush area sampled varies greatly com-pared to the proportion within the states (Table2). Thus, Breeding Bird Survey routes likelycapture neither the large-scale habitat featuresnor the smaller-scale dynamics along the gradi-ent of habitat configurations available to shrubs-teppe birds. Similar to most other habitats, sur-veys based on road networks may limit our abil-ity to estimate abundance over the full range ofavailable landscapes (Anderson 2001). Small-scale bias due to presence of unpaved or little-used roads on bird counts was insignificant insagebrush habitats (Rotenberry and Knick1995). Therefore, development of a new surveynetwork that samples the existing sagebrush dis-tribution but using unpaved roads still may bethe most practical means to survey large areas.To address gradients in habitat and bird dynam-ics, surveys need to be based on a standard setof sampling methods for habitats and birds thatincorporate local efforts into a broader programin a hierarchical design. Ultimately, counts, in-dexes, or density estimates need to be related tohabitat components and translated into estimatesof fitness or productivity per unit of area or hab-itat to understand source-sink dynamics andmechanisms underpinning population trends(Morrison 2001, Noon and Franklin 2002)



TABLE 2. Proportion of sagebrusha habitats within individual states relative to representation of sagebrushhabitats sampled on Breeding Bird Survey routes. Only routes sampled at least once from 1995 through 2001are included to reflect current conditions.

State Total area (ha)Area of sagebrush

ha (% of total)

Breeding Bird Survey routes

No. ofBBS

routes

No. thatinclude

sagebrushn (%)

Area sampledby all BBSroutesb (ha)

Sagebrush areasampled by BBS

routes ha (%)

CaliforniaColoradoIdahoMontanaNevadaOregonUtahWashingtonWyomingTotals

40 865 32626 963 05221 586 67038 137 54328 664 40925 142 83721 982 50317 428 66425 331 811

246 102 816

1 264 557 (3)1 898 437 (7)5 652 438 (26)2 421 715 (6)

10 876 551 (38)5 662 882 (23)3 740 229 (17)2 012 649 (12)9 568 981 (38)

43 098 435 (18)

237136

636743

127103

99117992

8 (3)38 (28)43 (68)24 (36)26 (61)29 (23)86 (84)45 (46)27 (23)

326 (33)

474 000272 000126 000134 000

86 000254 000206 000198 000234 000

1 984 000

3058 (1)17 993 (7)21 076 (17)

3388 (3)8683 (10)9348 (4)

35 183 (17)22 709 (12)

6871 (3)128 308 (6)

a As defined in Table 1.b Estimated by buffering each Breeding Bird Survey route by 250 m along each side of the 40-km transect.

MIGRATION AND WINTERING-GROUNDPROCESSES

Improving our ability to track migrating birds,identify wintering areas, and estimate mortalityduring the nonbreeding period may be the mostsignificant contributions that we can make to-ward understanding population dynamics ofshrubsteppe birds. Because population dynamicsof birds may be strongly influenced by mortalityduring the nonbreeding period (Fretwell 1972),focusing our attention solely on sagebrushbreeding areas risks overlooking the importanceof migration routes and wintering grounds. Win-tering areas for some species breeding in sage-brush habitats have been identified in the south-western United States and Mexico (Fig. 6).However, we do not know the migration path-ways these birds use or their yearly fidelity towintering ranges.

We need a new system of surveys designedto identify the spatial and temporal distributionof wintering birds. From these surveys, we candetermine habitats or regions important to win-tering birds, determine the influence of weatheron seasonal or yearly variation in areas used,and assess risks to birds from contaminants orhabitat loss.

The ability to link habitat and populationcomponents of shrubsteppe birds during breed-ing, migration, and wintering periods may pro-vide insights into annual fluctuations in popu-lations and area-specific productivity (Wiens andDyer 1975). To achieve this, technological ad-

vances in marking and tracking individuals andpopulations will be necessary. Banding infor-mation is limited because banded birds are rare-ly recovered. Most species, such as Sage andBrewer’s Sparrows, are too small (,25 g) to car-ry radio-transmitters that currently are available.For larger birds, such as Sage Thrasher (35–50g), battery life of radio-transmitters and detec-tion distances are too short to track betweenbreeding and wintering ranges. We only now aredeveloping transmitters sufficiently small for at-tachment to small birds and powerful to tracktheir movements over large distances and forlonger periods. Other techniques that do not dis-tinguish individuals, such as stable isotopes(Marra et al. 1998), may hold potential to deter-mine the extent to which breeding populationsmix or concentrate during the wintering periodas well as link wintering ranges of birds to theirbreeding ranges in northern sagebrush ecosys-tems.

CONCLUSION

Since the report of the Conservation Committeeof the Wilson Ornithological Society (Braun etal. 1976), land-use practices, invasion by exoticplants, disrupted ecosystem processes, and al-tered disturbance regimes have continued to im-pact sagebrush ecosystems. The continuedthreats to sagebrush ecosystems are numerous,and their consequences either will require longand expensive recovery or are largely irrevers-ible (Rotenberry 1998, Knick 1999). Aggressive



FIGURE 6. Combined breeding and wintering ranges of Brewer’s Sparrow, Sage Sparrow, Sage Thrasher,Green-tailed Towhee, and Gray Flycatcher. For conservation to succeed, researchers and managers must rec-ognize the continental scale at which sagebrush-breeding birds live. Ranges were delineated from individualBirds of North America accounts (Appendix).



management actions might stabilize current con-ditions. However, most management scenarios inthe interior Columbia River basin forecast de-clines in habitat condition and extent (Raphaelet al. 2001, Wisdom, Rowland, et al. 2002).

Responsibility for maintaining sagebrush hab-itats and bird populations rests squarely on pub-lic land management agencies because most spe-cies’ summer ranges are owned publicly andmanaged by state or federal agencies. The issuesalso are largely contained within the UnitedStates and Mexico because many of the birdsbreeding in sagebrush ecosystems are short-dis-tance migrants (Fig. 6). State and federal man-agement agencies appreciate the importance ofbirds and habitats in sagebrush ecosystems.However, resources currently expended on shru-bland birds fall far short of those necessary toaddress the issues. Development of a compre-hensive approach to bird conservation in sage-brush habitats requires a broad range of partner-ships, including state and federal agencies, aca-demia, and private organizations and landown-ers. Our research agenda incorporates a diversityof management needs and develops an integrat-ed approach to understanding the dynamics ofbird communities in sagebrush habitats.

Our primary challenge, presented over a quar-ter of a century ago (Braun et al. 1976), may beto convince our society of the intrinsic value ofsagebrush ecosystems and their unique biodi-versity. This change in mindset will have to befollowed by a firm commitment by federal andstate agencies to provide the resources necessaryto resolve issues presented in this paper. Onlywith this concerted effort and commitment canwe afford to be optimistic about the future ofsagebrush ecosystems and their avifauna.

ACKNOWLEDGMENTS

This paper was written in response to a request byTerrell D. Rich during his tenure as President of theCooper Ornithological Society, to report on the currentstatus of sagebrush ecosytems and provide a researchagenda for birds living in sagebrush habitats. Many ofthe ideas were discussed at a workshop, ‘‘The Effectsof Multiscale Landscape Changes on Populations ofBirds in Arid Lands of the Intermountain West,’’ inAugust 2001 in Boise, Idaho. The workshop was or-ganized by the USGS Forest and Rangeland Ecosys-tem Science Center. Sixty-five people attended theworkshop representing the U.S. Geological Survey,U.S. Fish and Wildlife Service, U.S. Bureau of LandManagement, U.S. National Park Service, U.S. De-partment of Energy, U.S. Department of Defense, and

USDA Forest Service; state wildlife agencies of Idaho,Nevada, Utah, and Washington; the University of Cal-ifornia-Riverside; Boise State University; Universityof Montana; Michigan State University; University ofNevada; Albertson College of Idaho; Idaho State Uni-versity; the Center for Conservation Research, Audu-bon Society; The Nature Conservancy; the High De-sert Ecological Research Institute; Partners in Flight;Point Reyes Bird Observatory; Idaho Bird Observa-tory; and Idaho Power Company. The workshop wasfunded by the USGS Forest and Rangeland EcosystemScience Center, Biological Resources Discipline andthe USGS Southwest Arid Lands Group, Geologic Dis-cipline. Boise State University provided additionalsupport. We thank R. E. Kirby, L. W. Oring, M. J.Wisdom, B. C. Schoeberl, B. A. Maurer, A. Hughes,F. L. Knopf, S. M. Haig, T. L. Sohl, L. S. Schueck, T.D. Rich, E. G. Campbell, M. A. Hilliard, and C. Mc-Carthy for their presentations and participation. S. E.Hanser, M. Leu, L. S. Schueck, and C. W. Meinkeassisted with the GIS analysis. We appreciate reviewsof the manuscript by C. E. Braun, J. W. Connelly, M.Leu, T. D. Rich, J. Sauder, J. M. Scott, and J. A. Wiens.

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APPENDIX. Bird species associated with sagebrush habitats, their primary habitat association (Paige and Ritter1999:12), and reference to the respective Birds of North America species account.

SpeciesSagebrushassociation

Birds of North Americaspecies account

Swainson’s HawkButeo swainsoni

Ferruginous HawkButeo regalis

Prairie FalconFalco mexicanus

Columbian Sharp-tailed GrouseTympanuchus phasianellus columbianus

Shrubland, grassland




England et al. 1997

Bechard and Schmutz 1995

Steenhof 1998

Connelly et al. 1998

Greater Sage-GrouseCentrocercus urophasianus

Gunnison Sage-GrouseCentrocercus minimus

Long-billed CurlewNumenius americanus

Burrowing OwlAthene cunicularia

Sagebrush obligate

Sagebrush obligate

Grassland

Grassland

Schroeder et al. 1999

Schroeder et al. 1999

Dugger and Dugger 2002

Haug et al. 1993

Short-eared OwlAsio flammeus

Gray FlycatcherEmpidonax wrightii

Loggerhead ShrikeLanius ludovicianus

Sage ThrasherOreoscoptes montanus

Green-tailed TowheePipilo chlorurus

Grassland

Dry woodland


Sagebrush obligate

Shrubland

Holt and Leasure 1993

Sterling 1999

Yosef 1996

Reynolds et al. 1999

Dobbs et al. 1998

Brewer’s SparrowSpizella breweri

Vesper SparrowPooecetes gramineus

Lark SparrowChondestes grammacus

Black-throated SparrowAmphispiza bilineata

Sage SparrowAmphispiza belli

Sagebrush obligate

Grassland

Shrubland

Shrubland

Sagebrush obligate

Rotenberry et al. 1999

Jones and Cornely 2002

Martin and Parrish 2000

Johnson et al. 2002

Martin and Carlson 1998


TEETERING ON THE EDGE OR TOO LATE? CONSERVATION … · the total area managed by the U.S. Department of Energy, 20% (3.6 million ha) of the total area managed by the U.S. Fish and

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