Knick, Steven T., David S. Dobkin, John T. Rotenberry, Michael A. Schroeder, W. Matthew Vander Haegen, and Charles Van Riper III. 2003. Teetering on the edge or too late? Conservation and research issues for avifauna of sagebrush habitats. The Condor 105:611-635.

RELEVANT TO: DECLINING SPECIES

SHRUBLAND/GRASSLAND VEGETATION AND WILDLIFE

LIVESTOCK GRAZING

INVASIVE SPECIES

MONITORING

DESCRIPTION

This document reviews and synthesizes the degradation, fragmentation and loss of native sagebrush (Artemisia spp.) landscapes and the resultant impacts on associated avifauna. It pays special attention to the effects of land-use practices on sagebrush such as habitat treatments, livestock grazing, agriculture and urbanization, energy development and the introduction of exotic plants.

The document then summarizes the effects of the resultant land use changes in composition and configuration of sagebrush habitats on birds living in these habitats. Recommendations regarding research and management strategies are suggested.

MAJOR FINDINGS

  1. Sagebrush habitats are among the most imperiled ecosystems in North America and shrubland and grassland birds are declining faster than any other group of species in North America. Some of these birds may be important predictors of impending collapse in sagebrush ecosystems because of their sensitivity to multiscale habitat changes. If the Greater Sage-Grouse or any of the other species living in sagebrush ecosystems is be listed under the Endangered Species Act, there will be major ramifications for use and management of large areas of the western United States (pp. 612-613).
  2. Livestock grazing in sagebrush. Virtually all sagebrush lands are managed principally for livestock grazing. This results in changes to habitat features that directly influence birds: (1) They reduce plant species diversity and biomass; (2) resultant changes in water and nutrient cycling can promote the spread of invasive species with degrades native bird habitats by altering fire and disturbance regimes; and, (3) grazing activities such as feedlots can facilitate nest predators or parasitism by Brown-headed Cowbirds (p 616).
  3. Fragmentation of sagebrush habitats caused by agricultural development, urbanization, roads, powerlines, and oil and gas development results in increased nest predation, cowbird parasitism and direct alteration of habitats at the site of ground-disturbing alterations. Such fragmentation and impacts to vegetation can create soils conditions facilitating the spread of invasive species. For example, density of sagebrush-obligate birds within 100 meters of roads constructed for natural gas development in Wyoming was 50% lower than at greater distances (Ingelfinger 2001). Increased numbers of corvids and raptors associated with powerlines also increase the potential impact of predation on sage grouse and other sagebrush-breeding birds (pp 616-619).
  4. Sagebrush reduction for livestock forage. Most studies of the effects to birds of habitat treatments intended to thin or reduce biomass of woody vegetation to improve forage production for livestock, etc. address only the short-term effects immediately post-treatment. In addition, the majority of studies did not sample pre-treatment conditions, had no controls or were of short duration. Experiments must provide greater insights into the mechanisms underlying habitat change and bird response (p. 620).
  5. Exotic plant invasion. Exotic plants such as cheatgrass are rapidly invading breeding and wintering ranges of birds. This invasion of alien plants is caused by many factors but includes emergency rehabilitation programs that continue to spread crested wheatgrass and other non-natives to stabilize soils. These plants alter vegetation composition, structure and disturbance regimes. The effects of non-native grasses on dynamics of birds in sagebrush communities have not been well studied. Restoration of some areas previously dominated by sagebrush may not be possible for both ecological and political reasons (p. 620).
  6. Bird conservation concerns. Sagebrush ecosystems support few bird species compared to other ecosystems. Approximately 18 bird species associated with sagebrush ecosystems are of conservation concern (see appendix of paper) (p. 621).
  7. Key information needs. Additional information and developing models would assist in understanding bird responses to habitat changes:
    1. Models of bird and habitat relationships at multiple scales may allow for predicting the response of bird communities to habitat changes.
    2. Modeling basic or minimum sets of habitat characteristics may allow a better understanding of components necessary to maintain bird populations.
    3. Development of regional vegetation maps and GIS-based analysis should permit identification of broad-scale variables that affect species distribution
    4. Historical information on long-term changes in bird distribution would improve understanding of habitat relationships.
    5. A long-term perspective on past fire regimes, vegetation changes, climate fluctuations, and anthropogenic impact would provide an important context in which to interpret current dynamics of sagebrush habitats and birds.
    6. Gaining an understanding of how habitat fragmentation influences productivity, density of breeding adults, size of home range, and other important variables would help manage these birds of conservation concern (p. 622).
  8. Recommendations include:

1. Experiments having strong statistical designs that include treatments and controls at relevant spatial and temporal scales are needed for pervasive lands uses such as livestock grazing.

2. A commitment to monitoring treatment projects planned by management agencies.

3. Implementation of sound management based on an understanding of the effects of land-use practices and enforced accountability to those policies may be the only way to ensure long-term survival of sagebrush habitats and their birds.

4. Enlarge existing protected blocks of sagebrush habitat, increase connectivity of these blocks in the landscape, and employ basic principles of landscape management to ensure long-term survival of sagebrush habitats and birds.

5. To counter the disastrous scenario of the continuation of exotic species invading sagebrush landscapes and degrading habitat, a federal policy is needed that requires the use of ecologically appropriate native plant species in all shrubsteppe restoration projects on public lands (p. 624).

6. Responsibility for maintaining sagebrush habitats and bird populations rests squarely on public land management agencies because most species' summer ranges are owned publicly and managed by state or federal agencies (p. 627).

QUESTIONS RAISED FOR THE THREE FORESTS

  1. What is the status of sagebrush habitats on these Three Forests related to fragmentation, invasive plant species, and effects of livestock grazing? Are any areas of sagebrush habitat on these Three Forests currently free of livestock? If so, what have the Forests learned from these areas that may assist in restoration of impacted sagebrush habitats?
  2. What invasive plant species are known to be present in sagebrush habitats on these Three Forests? How widespread is the problem? Is there a policy to use only ecologically appropriate native seed during restoration (due to wildfire or for other reasons) in these habitats?
  3. What implication does the imperiled status of sagebrush habitat across the West and the resultant decline in sagebrush-obligate bird species have on the future management of these Three Forests?
  4. How can the Three Forests ensure that appropriate and useful monitoring of on-going management practices (e.g. livestock grazing) and future management practices in sagebrush habitats help to further our understanding of these ecosystems?
  5. How can the Three Forests increase their protection of large blocks of sagebrush habitat?

RELEVANCE TO FOREST MANAGEMENT

  1. Sagebrush habitat on these three Forests that has been invaded by exotic species must be examined for possible restoration with native vegetation.
  2. Audubon breeding bird surveys could be established in the Three Forests' sagebrush habitat.
  3. Large blocks of sagebrush habitat need to be livestock-free for (a) benefits for sagebrush-dependent species; and (b) comparison with livestock-grazed sites.
  4. Selection of one or more imperiled sagebrush-dependent bird species such as the Vesper Sparrow (Pooecetes gramineus) and/or Brewer's Sparrow (Spizella breweri) as management indicator species within the three Forests is appropriate.