Description and Ecology: The habitat category of wetlands 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 a l. 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 million 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
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 also 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
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.
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). However two species are in need of special conservation
attention in Colorado: Northern Harrier and Short-eared Owl.
In the water-restricted western United States, water resources are necessary for life, and control
of water has 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 Central Shortgrass Prairie are not available, and interpretations are very complicated
because of the large number of created wetlands.
Many wetland manipulations resulted in the addition of many acres of wetlands (Kingery 1998).
For example, large irrigation canals move water from mountain rivers or streams into the prairie.
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 create
wetlands such as wet prairie, 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 the wetlands of Colorado's prairies 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. (This does not imply
good or bad since there may be a significant change in wetlands or habitat type with the creation
of these wetlands. It is important to remember that different wetland types are not equivalent in
biodiversity terms.) The extensive patchwork of reservoirs in the Denver metropolitan
area--from Fort Collins to Pueblo-- has greatly changed the regional avifauna. Birds that were
undoubtedly rare or absent prior to European advancement are now common (e.g., some gulls,
many waterfowl, and some wading birds). Outside of the metropolitan area, large reservoirs such
as Jackson Reservoir, Bonny Reservoir, John Martin Reservoir, Neenoshe Reservoir, and many
others have created large areas of wetlands, open water, shore/bank, and riparian habitats that are
novel in the physiographic area.
The 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.
Playas deserve special mention. Playas are variably sized depressions in the prairie that are
usually dry. However, during wet periods, especially after heavy thunderstorms, these
depressions are often filled with water and teeming with birds. In much of the physiographic area,
1998 and 1999 were wet years, and the playas provided nesting, feeding, or resting grounds for an
abundance of waterfowl, wading birds, and shorebirds. The playas vary in size from hundreds of
square feet to several square miles.
The unpredictability of playas as a wetlands resource may be one factor that has led to a lack of
attention from Colorado's conservation community; some playas have been filled for many years
(e.g., in Huerfano County near the Spanish Peaks), but most have been filled only 2-3 years in a
decade. Livestock producers often try to increase the capacity of playas in an attempt to maintain
surface water for longer periods, and wildlife managers have long sought means of increasing the
time that water is available in larger and deeper playas; however, other playas have been lost in
the conversion of prairie to croplands. In the wettest years, these playas are visible as ponds
within a sea of crops (C. A. Pague, The Nature Conservancy, personal observation).
Current threats to wetlands include water diversions, draining, manipulation, intensive use by
livestock, conversion to cropland, and conversion to residential uses in the metropolitan area
(Windell 1986). Threats include direct losses--conversion of wetland types--and contextual
changes. Interestingly, the pressure to provide water to urban populations has stimulated the
acquisition of water rights by municipalities from large areas of the plains (e.g., Rocky Ford Ditch
1999). Such acquisitions have resulted in large areas of prairie having their local hydrology
returned to a more natural state.
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 in Colorado's Central Shortgrass
Prairie. The wetland types that support most wetlands bird species are playas, marshes, wet
meadows, lakes, and ponds. The status of these wetland 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 for wetland habitats
in Physiographic Area 36: Northern Harrier and Short-eared Owl.