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Publication Date

12-1-2010

Abstract

As part of a cooperative effort of southeastern states, we conducted an aerial survey from 9–17 February 2009 to determine major concentration areas for wintering shorebirds along the Texas Gulf Coast. Shorebirds were surveyed from a Partenavia P-68 based out of Victoria with two observers viewing on either side of the airplane while flying at an altitude of 30 m (100 ft.) and flight speed of 185 km/h (100 knots). Shorebirds were placed into size categories when counted because of difficulty of identifying birds to species under the conditions of the survey but were tallied to species where possible. All likely high shorebird concentrations within tidal zones were searched between the Sabine and Rio Grande rivers. Approximately one-third of the major tidal marsh areas were surveyed due to limitation of available air time. Only freshwater wetlands adjacent to tidal marshes were surveyed. Five airplane hours were used surveying Sabine Lake to High Island, 7 h Galveston and Matagorda Bays, 6 h San Antonio Bay and Matagorda and San Jose Islands, 3 h Nueces and Corpus Christi Bays, and Mustang Island, and 9 h Baffin Bay and Laguna Madre. Five thousand shorebirds were found between the Sabine River and High Island, 45,000 in the Galveston Bay complex with 16,000 at Bolivar Flats, 11,000 in marshes west of Texas City and 7,000 at the mouth of the Trinity River, 38,000 near Matagorda Bay with 11,000 at the mouth of the Colorado River, 46,000 on Matagorda and San Jose Islands and San Antonio Bay with 16,000 on Matagorda Island, 2,500 on Nueces and Corpus Christi Bays and Mustang Island, and 89,000 on the Laguna Madre system with 60,000 concentrated in the “9-mile Hole” and 11,000 along Baffin Bay on the Upper Laguna Madre and Baffin Bay. The Lower Laguna Madre had 95,000 with 68,000 using tidal areas between Port Mansfield and the Arroyo Colorado. The 330,000 shorebirds were comprised of 257,000 small size, 33,000 medium size, and 1,000 large size. There also were 14,000 American Avocets (Recurvirosta americana), 4,000 Willet (Catoptrophorus semipalmatus), and 1,200 Marbled Godwit (Limosa fedoa). Ground surveys conducted during the same time indicated the bulk of small shorebirds were Western Sandpiper (Calidris mauri) and Dunlin (Calidris alpina), and medium shorebirds comprised of mostly dowitchers (Limnodromus spp). Density and distribution of wintering shorebirds found during this survey assist conservation planners in focusing their efforts on habitat conservation.

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