Bird Species Richness, Occurrence, and Abundance

Across the nation, land birds have experience a dramatic decline over the past century. Undeveloped tracts of land are critical for the conservation of many of these bird species. In Texas, most of these lands are owned and managed by private landowners. The East Foundation is committed to leading wildlife conservation efforts across its native rangelands.

Breeding bird surveys have occurred on Foundation lands since 2008 aimed at determining what species are present and whether populations are increasing, remaining stable, or decreasing.

Each year, observers conduct point counts along 24.5 miles of roadways with a point every 0.5 miles. Specifics of the surveys include:

  • Conducted on the San Antonio Viejo, El Sauz, and Santo Rosa ranches
  • Occur from late-May to early-June, during the peak of the breeding season
  • 3 minute count of all birds present within a 200 yard radius of each point

Key findings:

  • Documented 8,126 individual birds of 101 different species
  • Lowest average number of birds per point was in 2009
  • Highest average number of birds per point was in 2014
  • Increasing trend in the overall number of land birds on all 3 ranches

There are several factors potentially influencing the increase in land bird numbers that are acting individually or in tandem, including increased rainfall in 2013 and 2014 following several years of drought. Drought conditions reduce food availability, abundance, and productivity in many bird species.

The East Foundation is uniquely positioned, with its lands representing a full range of conditions for South Texas, to determine trends in land birds for the entire region. Future efforts will seek to determine the drivers of rangeland bird abundance and diversity.

Partner: Caesar Kleberg Wildlife Research Institute

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