Each month, we get to know one of the state’s many wonderful and quirky critters. Latin name: Falco sparveriusSize: 8 to 12 inches long; wingspan is 20 to 24 inchesTexas habitat: Statewide North America’s smallest and most numerous falcon flocks to Texas throughout fall and winter, hunting our grasslands and even our suburbs. With their acrobatic flying maneuvers and tawny and blue-gray plumage, American kestrels are a joy to watch. “They have that feisty attitude,” says Jim Bednarz, a professor and avian ecologist at the University of North Texas, in Denton, who studies kestrel migration patterns. “I like to call them badasses.” But kestrels are also experiencing a perplexing population decline. Badasses? Tell me more.These flashy fliers put on a show, defending their territory from much larger raptors,…