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Playas are one of the most numerous wetland types in the western
Great Plains, but because they only fill periodically from heavy rainfall, they
are very difficult to map and to study. The wet-dry cycles of playas produce high
abundances of insects and annual plants that provide nutritious seeds, especially
important to migrating waterfowl and shorebirds in our region that stop over on
playas to rest and refuel during their long journeys between wintering and breeding
grounds. These shallow, seasonal wetlands also provide other important societal
wetland functions, including capture of surface runoff, flood attenuation, and aquifer
recharge. However, it is estimated that nationally over 50% of all wetlands have
already been lost, and current threats to playas include pressure from growing urban
development and agricultural uses that lead to increased sedimentation rates, pit
excavation, road construction, feedlot runoff, overgrazing, and deliberate filling.
Because this is a vitally important resource and little was known about the locations,
conditions, and wildlife use of playas in western Nebraska, we initiated this study
in 2006.
We are studying bird and amphibian use of playas following heavy rain in southwestern
Nebraska, where we estimate as many as 16,000 playas exist (see
map). Use by birds and frogs and toads in this wetland system had never
before been described. We are also exploring how the frequency and duration of inundation
in playas (e.g., when they get wet) may be affected by surrounding land use. This
partnership with the Nebraska Game and Parks Commission, Playa Lakes Joint Venture,
and the U.S. Fish and Wildlife Service builds a source of information for landowners
and other partners interested in conserving these wetlands for future generations.
Our study approach combines rainfall tracking, aerial surveys, ground surveys, GIS
data analysis, and statistical modeling to relate bird use (as well as playa hydrology
and frog and toad use) to various factors such as size of the wetland, landscape
context, and human impacts. Click here for our main objectives
and findings of the project to date. This project is ongoing, with a final report
to be generated in 2009.
In addition to this research, Rocky Mountain Bird Observatory directly conserves
playas by working with private landowners (approximately 95% of western Nebraska
is in private ownership) through Nebraska Prairie Partners, which offers voluntary,
incentive-based programs to enhance and restore playas for
future generations. These are win-win situations for wildlife as well as agricultural
producers. Private landowners are interested in conservation programs for playas
for a variety of reasons, including the recreational opportunities (hunting and
wildlife viewing), aquifer recharge benefits, and because playas can be problematic
for farming and ranching. Conservation programs may entail grazing management and
alternate water development or retirement and buffering the playa from farming and
usually entail cost-share agreements and/or rental payments.
Related Projects
We are also conducting a Survey and Assessment of Playas in Eastern
Colorado.
In another related project,
Floristic Quality and Wildlife Habitat Assessment, we investigate how bird
use, plant composition, and human disturbance relate within playa wetlands of eastern
Colorado.
Primary Objectives and Findings to Date:
- Quantify the diversity and abundance of bird species using wet playas during
the spring and fall migration seasons.
- We have collected bird use data for fall 2006, spring 2007, fall 2007, and currently,
fall 2008 data.
Through 2007, we have documented over 123,000 birds representing
- 136 species, including 22 species of concern.
- Describe amphibian species composition and frequency of occurrence in playas.
- Using nocturnal calling surveys, we documented use of playas by four species of
frogs and toads during spring 2007.
- Frogs or toads were present in 93% of the playas surveyed.
- Correlate bird and amphibian use to habitat variables within the wetland and
landscape attributes of the surrounding watershed.
- We created preliminary habitat use models
for shorebirds and waterfowl using 2006-2007 data.
- We found that shorebirds were more abundant on playas in Shortgrass prairie (relative
to cropland or buffer programs), with unmodified hydrology (i.e., not pitted), and
with more acreage of playas in the surrounding landscape.
- Waterfowl abundance was inversely related to distance of the playa center to the
nearest road. Playa size and percent flooded were also significant in both models.
We will continue refining these complex statistical models this winter, incorporating
2008 data, and this may modify final conclusions.
- Using aerial photography, quantify playa hydroperiod response to different precipitation
events, including the effects of playa size, watershed size and condition, and dominant
land use in the watershed on playa hydroperiod.
- We collected aerial photography
in August of 2006 and May 2008 to assess the responses of playas to heavy rainfall.
- Analysis of the 2006 data indicated that playas located in buffer (primarily CRP)
landuse were less likely to become wet than playas located in cropland or grassland.
- In 2006, most playas maintained hydroperiods through the end of October due to a
succession of rain events.
- Analysis of the 2008 data is not yet complete.
- Correlate various Geographic Information System (GIS) data layers, including
satellite imagery (from PLJV), National Wetland Inventory (NWI), Soil Survey Geographic
(SSURGO), and aerial photography (from USFWS) to create a comprehensive map of playas
in the region.
- We have completed three updates to the GIS model, incorporating new data found from
field and aerial surveys.
- After compiling the data collected in 2008, we will release a comprehensive map
for use by all conservation partners.
More about Playas
Playas are shallow, depressional wetlands of the Great Plains that fill periodically
from heavy rainfall and associated runoff (Smith 2003). Over 60,000 occur throughout
northern Texas, western Oklahoma, Kansas, Nebraska, and eastern New Mexico and Colorado
(Playa Lakes Joint Venture 2008). Playa wetlands provide important ecological and
societal functions (Haukos and Smith 1994), including flood abatement, recharge
to the Ogallala aquifer (Zartman 1994, Wood 2000), water for livestock (Ostercamp
and Wood 1987), support for biodiversity (Bolen et al. 1989), critical shorebird
migration stopover habitat (Skagen and Knopf 1993; Davis and Smith 1998), and winter
and migration habitat for waterfowl (Nelson et al. 1983). Playas are threatened
by development pressures and agricultural uses that have led to increased sedimentation
rates, pit excavation, road construction, feedlot runoff, urban development, overgrazing,
and deliberate filling (Haukos and Smith 2003). Finally, because these clay-lined
wetlands occur in closed watersheds, they are considered geographically isolated
and not currently protected under the Clean Water Act (Haukos and Smith 2003). To
learn more about playas go to www.pljv.org.
Programs
RMBO is joined by many others in the conservation community that also offer playa
conservation programs, including the Colorado Division of Wildlife (CDOW), Nebraska
Game and Parks Commission, (NGPC), U.S. Fish and Wildlife Service (USFWS) Partners
for Fish and Wildlife Program, Playa Lakes Joint Venture (PLJV), and the Natural
Resources Conservation Service (NRCS).
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Contact:
Alison Cariveau
Alison.Cariveau@rmbo.org
State: Nebraska
Funder:
- Nebraska Game and Parks Commission
- Playa Lakes Joint Venture
Cooperators:
- U.S. Fish and Wildlife Service
Materials:
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