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Publication Date

12-1-2011

Abstract

Texas Parks and Wildlife Department (TPWD) staff and volunteers conducted ground and air surveys of inland colonial waterbird nest sites at 584 locations in Texas from 1973 through 2004. There was an average of 472,466 nesting pairs sighted per year at all colonies. Cattle Egret (Bubulcus ibis), Little Blue Heron (Egretta caerulea), Snowy Egret (Egretta thula) and Great Egret (Ardea alba) were the most abundant species. The Oaks and Prairie Bird Conservation Region (BCR 21) had the most colonies with 171 and 269,210 nesting pairs. The total for the average densities for each colony from ground surveys from 1981-1990 in eastern Texas was 300,421 breeding pairs compared to 282,925 pairs observed from the air in 2002-2003. These totals were greater than the 164,720 pairs reported in coastal bays by the Texas Colonial Waterbird Society in 2003. Ground surveys in the 1980’s documented some of the largest nesting populations of Little Blue Herons in the United States, but aerial surveys from 2002-04 found only 50% of the previously reported birds with few in northern counties. This population either shifted location or declined in northern counties before the aerial surveys. Great Blue Heron (Ardea herodias) and Neotropic Cormorant (Phalacrocorax brasilianus) occurred in greater numbers inland than elsewhere in Texas. The combined ground and the air surveys over 31 years provided a good characterization of the density and distribution of colonial waterbirds nesting inland in Texas. We recommend future aerial surveys be conducted at least once per decade to continue to monitor the distribution and size of colonies of each species in eastern Texas where the bulk of nesting occurs.

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