Land Bird Conservation Plan Colorado  

Executive Summary
Overview of Colorado
Physiographic Region 36
Physiographic Region 62

  • Alpine Tundra
  • Aspen
  • Cliff/Rock
  • High Elevation Riparian
  • Lowland Riparian
  • Mixed Conifer
  • Mountain Shrubland
  • Ponderosa Pine
  • Sagebrush Shrubland
  • Spruce Fir
  • Wetlands


  • Physiographic Region 87
    Implementation Strategies
    Literature Cited
    Appendices

    Physiographic Region 62: Southern Rocky Mountains

    Green-tailed Towhee (Pipilo chlorurus)

    Associated Species: Other species that may use habitat in a similar way and/or respond similarly to threats, management, and conservation activities include Dusky Flycatcher, House Wren, Sage Thrasher, Virginia's Warbler, and Spotted Towhee.

    Distribution: Green-tailed Towhees breed in the montane and plateau interior of the western United States at an average elevation of 2200 m (7,300 ft). In Colorado, they breed from the eastern foothills through the western part of the state and are absent only in Intermountain parks. However, they are locally rare in higher mountain shrublands particularly where upland shrub density is lower or absent (Andrews and Righter 1992). Green-tailed Towhees winter from central Arizona, New Mexico, and Texas south into Mexico.

    Habitat Requirements: Green-tailed Towhees breed in dry shrubby hillsides (Gambel oak, mountain mahogany, serviceberry, sagebrush, snowberry, chokecherry, and antelope bitterbrush), in sagebrush flats, and on slightly moister soils within hillside shrublands around rock outcrops where Ribes is found. They are also found in ponderosa pine savannah habitat with shrub understory. They also use hillsides in scattered aspen trees intermixed with shrubs. Additionally, these towhees reside on hillsides covered with pinyon and junipers, as well as in riparian shrublands. They avoid dense forests except in openings and where conditions allow shrubs to form (Bent 1968). They are most often seen at altitudes between 1830 to 2750 m (about 6,000-9,000 ft).

    Ecology: Green-tailed Towhees' nesting season extends from the first of May through mid August.

    Management Issues and Conservation Recommendations: Conflicts related to the nesting, resting, and foraging of Green-tailed Towhees include mining, road construction, hiking trails, fire, conversion of rural areas to urban subdivisions (ski resorts), and intentional alteration of habitat to enhance livestock grazing. Large scale prescribed fires that eliminate the shrub component would be detrimental to this species. Survey areas for breeding Green-tailed Towhees before considering altering mountain shrubland by herbicide treatment, mechanical alteration, or burning. Strive to produce landscape-scale mosaics of altered and unaltered habitat, and to prevent invasion of exotic plants such as cheatgrass or noxious weeds. Schedule prescribed burning in early spring before birds arrive and not during the bird's breeding and nesting season. Ensure that prescribed fires leave adequate amounts of unburned shrubs to provide breeding habitat.

    Identify historic habitat (e.g., agriculture zones, urban areas) that once was or may have been mountain shrub habitat. Identify areas of the state where Green-tailed Towhee habitat may be threatened due to urban or rural development. Research threshold levels below which Green-tailed Towhees drop in significant breeding numbers to determine where the critical loss of shrub cover occurs. Rotate livestock grazing to provide rested pastures during the nesting season to respite from cowbird parasitism.

    Status and Reasons for Concern: Colorado contains between 20% and 40% of the entire breeding population of Green-tailed Towhees (Kingery 1998); therefore, Colorado has high responsibility for the conservation of this species. Colorado Breeding Bird Atlas abundance calculations rank this towhee as the thirteenth most numerous species in Colorado, with almost a million breeding pairs (Kingery 1998). Mountain shrubland habitat in Physiographic Area 62 is one of the most important breeding habitat types for Green-tailed Towhees. Despite high counts on BBS routes, the BBS data proved inadequate to provide accurate population trends for either Colorado or North America (Kingery 1998). Within Physiographic Area 62, Green-tailed Towhees were present on an average of 87.48 (SE = 2.56) of BBS routes, 1988-1997, at an average abundance of 12.20 (SE = 1.10) individuals per route. The mean number of routes run each years was 21.1 (SE = 3.06). This species is monitored by MCB with point transects.

    Biological Objective: Maintain or increase Green-tailed Towhees' distribution and abundance, based upon results of the BBS and MCB monitoring programs.

    Selected References: Andrews and Righter 1992, Bent 1968, Dobbs et al. 1997, Kingery 1998, Paige and Ritter 1999, Udvardy 1977.


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