Prioritizing Conservation of Coastal Ponds for Wintering Redheads

The Laguna Madres of Texas, USA, and Tamaulipas, Mexico, are the most important wintering areas for redheads (Aythya americana) as most of the continental population winters in these lagoons. Redheads forage in the saline waters of the Laguna Madre and make daily flights to coastal freshwater ponds on the adjacent mainland to drink. The abundance and spatial distribution of coastal ponds varies depending on precipitation and can influence the foraging pressure on adjacent seagrass meadows. We conducted weekly aerial surveys to monitor coastal pond use by wintering redheads from mid-October through mid-March along the entire length of the Laguna Madre of Texas, during 2000–2003 and in 2012–2014. We developed 3 parameters to provide a measure of biological value of each coastal pond to redheads: amount of foraging habitat within 10 km of each pond, water permanence of the pond, and the potential to distribute redheads if inundated. During 101 aerial surveys across 5 years of study, we identified 140 coastal ponds that were used by redheads. We developed a prioritization scheme to identify wetlands that remain inundated in all years and targeted them for conservation protection. We identified those coastal ponds that, if enhanced through increasing their water permanence, would provide additional drinking sites during dry years and help distribute redheads on more foraging habitat, thereby reducing potential overgrazing on seagrass meadows. We identified 3,624 ha of foraging habitat (21.5% of all foraging habitat) in the lower Laguna Madre that had no coastal ponds within a 10-km radius and, thus, was proximal to potential areas for coastal pond creation. Our results provide guidance for resource managers to protect, enhance, or create coastal ponds to reduce foraging pressure on seagrass meadows in the Laguna Madre and help sustain future populations of wintering redheads.