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A study to determine waterfowl breeding habitat preferences on the Llano Estacado was undertaken from May to September 1977 . A brood site survey of 37 playas was conducted in Castro , Floyd , Hale , and Swisher counties to find out the playa lake type preferred by brooding hens . Biweekly surveys of eight playa lakes in Castro and Swisher counties were conducted to determine physico -chemical characteristics of playa lake water , macroinvertebrate populations , vegetative characteristics and their relationships to brood use of individual playas . Brooding hens in the four surveyed counties preferred natural playa lakes (8l percent use ) to mechanically modified playas . However , mechanically modified playas with extensive littoral zones received about six times as much use as modified playas with no littoral zone . A step -wise regression analysis showed that the area of emergent vegetation over 0 .5 m tall , height of emergent vegetation over 0 .5 m tall and lake turbidity could account for 99 .2 percent of the variation in brood use from one playa to another . This study suggests that waterfowl production on the Texas High Plains can be markedly increased by manipulating playa lakes to encourage the taller emergent plant species and by preservation of shallow water zones in playa lake basins . |
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