Land Bird Conservation Plan Colorado  

Executive Summary
Overview of Colorado
Physiographic Region 36
Physiographic Region 62
Physiographic Region 87

  • Cliff/Rock
  • Lowland Riparian
  • Mountain Shrubland
  • Pinyon-Juniper
  • Ponderosa Pine
  • Sagebrush Shrubland
  • Semidesert Shrubland
  • Wetlands
  • Implementation Strategies
    Literature Cited
    Appendices

    Physiographic Region 87: Colorado Plateau

    Wetlands

    Description and Ecology: The wetlands habitat category encompasses a large variety of ecosystems of large and small proportions. The state of Colorado has numerous representatives of this variety: marshes, wet meadows, seeps, springs, rivers, lakes, ponds, swamps, fens, bogs, hanging gardens, and playas (Windell et al. 1986, Benedict 1991). Many of Colorado's wetlands, including some that support priority species, are artificial. Such wetlands include irrigated meadows and man-made reservoirs, lakes, and ponds with their associated marshes. Less than 3% of the surface area of Colorado originally occurred as wetlands (Dahl 1990). Approximately 40% to 60% (0.4-1.2 ha; 1-3 million ac) of the original wetlands area has been lost (Dahl 1990, Wilen 1995). Losses are greater proportionately in wetlands than in other habitat types in Colorado.

    Wetlands in Colorado range in size from a few square meters (e.g., springs and splash pools) to large areas of wet meadows and riparian wet forests. They include wetlands along riparian corridors that may continue for many kilometers, yet are quite narrow. (Discussion of riparian habitats will be found in the appropriate section: lowland riparian or high elevation riparian habitats.) What all wetlands have in common is water. The water occurs in sufficient quantities and in such patterns that the soils, geomorphology, and vegetation respond characteristically, forming repeated patterns on the landscape. The repeated patterns are categorized as types of wetlands.

    All wetlands likely play a role in the lives of birds, at least as sources of water. But many wetland types are very small and unlikely to make a large contribution to Colorado's avifauna. (Although any wetlands may be important to local conservation.) Wetlands that support high priority bird species include lakes, ponds, reservoirs, wet meadows, playas, and marshes. The remaining, smaller wetlands are perhaps best considered as patch types and important habitat components within a larger habitat matrix.

    Physiographic Area 87 contains a number of Colorado's most significant wetland areas. In the San Luis Valley, Alamosa and Monte Vista National Wildlife Refuges, Russell Lakes and San Luis Lakes State Wildlife Areas, Blanca Wetlands, and Cotton Lake host concentrations of wetlands birds that are among the state's largest. On the Colorado Plateau in western Colorado, Fruitgrower's Reservoir and Browns Park NWR both provide habitat for large numbers of nesting and migrating wetlands species. Numerous wet meadows dot the ranch lands in the river valleys.

    Importance and Conservation Status: Thirty-seven of Colorado's breeding bird species are dependent on wetlands. That means that 14% of the breeding species depend on less than 3% of the state's area. Many of the species are common and are presently of little current conservation concern (e.g., Red-winged Blackbird).

    In the water-restricted western United States, water resources are necessary for life, and control of water can become a most lucrative asset. Water law in Colorado, as in most western states, recognizes water as one of a bundle of property rights. As such, water is owned, bought and sold, as property. For mining operations, agricultural irrigation, and drinking water for a growing population, water has been harnessed, moved, stored, slowed, and spread. Wetlands have often been considered impediments to efficient water use, slowing its downstream progress to areas of human use. Many wetlands have been drained and others heavily altered. Dahl (1990) estimated wetland losses in Colorado to be approximately 50%. More specific estimates for wetland losses in the Colorado Plateau are not available, and interpretations are very complicated because of the large number of created wetlands.

    Wetland manipulations have resulted in the addition of many acres of wetlands (Kingery 1998). For example, irrigation canals move water from mountain rivers or streams into the desert. Some of the water escapes the confines of ditches and leaks into the surrounding landscape; this escaped water often creates artificial springs. Vegetation changes around such seepages are often the emergence of wetlands such as wet meadows, small standing waters, shrub thickets, and woody groves. Such areas are often rich with birds, and where trees and shrubs occur, the associated birds may represent those found in riparian habitats. The largest changes in Colorado's wetlands came from the creation of water storage facilities, reservoirs and ponds (Kingery 1998). These reservoirs are often placed on top of existing wetlands where they may greatly expand the total wetland acres.

    Wetlands that support high priority bird species in Colorado have shown variable changes over the past 150 years. Shallow lakes and ponds that supported large populations of breeding waterfowl have declined in many areas. Instead, reservoirs are often maintained with little vegetation. A common goal of water users is to provide the smallest surface area of water to limit evaporation losses; this goal often creates wetlands habitats that are relatively sterile.

    It is difficult to assess the status of marshes since agricultural practices have created numerous marshes. However, it is clear that native graminoid-dominated marshes have clearly suffered extensive losses, even more when the condition of the landscape in which they occur is considered (J. Sanderson, personal communication). For example, a marsh may have adequate breeding habitat for Northern Harriers, but a landscape that is inadequate or ecologically dysfunctional.

    The concept of no net loss of wetlands appears to be adequate for protecting the associated birds in Colorado. However, existing guidelines for wetlands mitigation, i.e., the focus on jurisdictional wetlands, rarely give adequate attention to bird communities or high priority species that are not given legal status. Cumulative changes of wetland types and loss of ecosystem-level biological attributes continue to reduce the amounts of wetlands habitats that are suitable for the more sensitive wetlands species. Recommendations for making wetlands mitigation more suitable for birds are laudable but may not adequately address the concerns for the most sensitive species.

    In summary, wetlands habitats are diverse and widespread on the Colorado Plateau. The wetland types that support most wetlands bird species are playas, marshes, wet meadows, lakes, and ponds. The status of these wetlands communities is checkered, with an increase in lakes, ponds, and seeps. Losses of springs, wet meadows, and playas are notable. Marshes have probably declined somewhat, but mostly have changed from native condition to altered and scattered patches.

    Priority Species Accounts: Two species are identified as high priority in wetland habitats in Physiographic Area 87: Northern Harrier and Short-eared Owl.


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