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Avian Point Count Study

Because birds are important indicators of an environment’s health, the avian point count study was conducted from February 2005 through April 2011 to gauge the environmental impact of the Wash stabilization and habitat enhancement program.  The study was funded through a grant from the U.S. Bureau of Reclamation.

While the census conducted with the Red Rock Audubon Society allowed us to collect detailed information regarding the bird community at one specific site, the point count study gave us the ability to gather data along the length of the lower Wash, providing a snapshot of the bird community for more than six years. 

The term 'point count' refers to the method used to conduct the study.  When using this method, ornithologists periodically visit a series of pre-established points at which they conduct time-limited counts.  For the purposes of this study, we established more than 30 sites and selected a five-minute count period.  Sites were visited once every two weeks.  This frequency allowed us to better record migrants and other species moving through the area that use Wash resources for a limited period of time and then move on.  It also allowed us to more accurately identify when summer and winter resident species arrive at the Wash.

Las Vegas Wash avian point count study sites
Las Vegas Wash avian point count study sites (PDF) (click for larger view)

Points were located in wetland, riparian and upland habitats, in areas where stabilization and revegetation activities have already occurred, as well as in areas where these activities will occur in the future or will never occur.  Comparing birds in each of these environments provided information regarding the impact of the stabilization and enhancement program in the Wash over time. Vegetation data collected at each site allowed us to make habitat/species associations and to track any changes in birds using a site as vegetation changes occur (e.g., tamarisk clearing, native plant revegetation, and revegetation site maturation).

Data was collected by San Bernardino County Museum for the first four years and by the Great Basin Bird Observatory for the remaining years. The study recorded 185 species, some of which had not been reported in the Wash for more than 30 years, including the ladder-backed woodpecker, gray flycatcher and house wren. A nesting, long-eared owl also was identified, a bird for which no prior Wash records could be found. A comparison of treatment types using 2010 data showed that older revegetation sites had higher cumulative bird species richness and higher total abundance than other treatment types, which included no treatment (typically tamarisk-dominated), cleared but not revegetated, and newer revegetation sites (younger than five years old).

Species Restoration Treatment ANOVA
No Treatm. Cleared New Reveg. Old Reveg. R²-Value p-Value
Cumulative Richness per Point 34 26 37.2 39.9 0.29 0.03
Total Abundance (# birds/40 ha) 121.5 104.3 154.0 183.7 0.28 0.03

Reports for this study can be found in the Document Library.

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Las Vegas Wash Project Coordination Team • 100 City Parkway, Suite 700 • Las Vegas, NV 89106 • (702) 822-3300