Northern Bobwhite Abundance in Las Coloraditas

The South Texas Sand Sheet is a hotspot for northern bobwhite population abundance and quail management is a significant economic driver.  Throughout the region, historic overgrazing by cattle has negatively impacted native rangelands and corresponding quail habitat.  This has led some quail-focused landowners to remove cattle altogether, which often produces unintended negative consequences.  The East Foundation believes that ranching and wildlife go together and that cattle grazing is an important part of land stewardship, particularly in this hyper-diverse region.  We aim to demonstrate relationships between cattle management and bobwhite abundance through research.

As part of the Las Coloraditas Grazing Research and Demonstration Area (CGRDA) we have initiated a project designed to monitor and compare quail abundance at 2 different cattle densities, under both continuous and rotational situations. We also selected 3, 4,000-acre reference pastures outside of the CGDRA to monitor concurrently. Grazing on the CGDRA was deferred from March 2014 to December 2015.

We used line-transect distance sampling from an aerial platform to determine bobwhite density each December, 2014–2017.  We found:

  • From 2014 to 2015, during the grazing deferred period, bobwhite density pooled across the CGRDA treatment pastures increased from 0.21 (0.15–0.26) birds per acre to 0.54 (0.39–0.53) birds per acre. Pooled across the reference pastures, density increased from 0.22 (0.15–0.30) birds per acre to 0.26 (0.21–0.33) birds per acre.

  • From 2015 to 2016, one year after cattle were restocked on the CGRDA, bobwhite density pooled across the CGRDA increased to 0.77 (0.66–0.90) birds per acre. Pooled across the reference pastures, density increased to 0.42 (0.32–0.54) birds per acre.

  • From 2016 to 2017, two years after cattle were stocked on the CGRDA, bobwhite density pooled across the CGRDA decreased to 0.29 (0.24–0.34) birds per acre. Similarly, pooled across the reference pastures, density decreased to 0.25 (0.19–0.32) birds per acre.

Bobwhite density estimates on the CGDRA between treatments within each year were similar, but fluctuated between years. Precipitation was likely a large determinate of annual fluctuations in density. We began sampling following a 3-year drought in 2014 and then experienced two years of above average precipitation in 2015 and 2016. Dry conditions have persisted on the study sites since July of 2017.

The East Foundation is committed to conducting research that makes a difference.  Data collected over the next 10 years in the CGRDA will shed light on cattle management and bobwhite abundance at an operational-scale (4,600-acre treatment pastures).  This is only one of the many big questions that will be addressed through the Las Coloraditas project.

Partners: Caesar Kleberg Wildlife Research Institute and Institute of Renewable Natural Resources

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