Miles of trails on two migratory routes for a wide variety of species make the 2,088-acre Santa Ana National Wildlife Refuge one of Texas's brightest "jewels in the crown" of birding sites. The refuge is located along an east-west and north-south migratory juncture and it's also at the northernmost end of the range for species who migrate down to Central and South America. The best time for birders to come is in late winter and early spring. Look for grebe, northern beardless trannulets and olive sparrows. At night, Eastern screech owls, elf owls, and lesser nighthawks emerge. The refuge's Tree Top Tower and Canopy Walk offer unique elevated perches from which to watch the over 400 species that migrate or make their home here including tricolored heron, osprey, broad-winged hawks, peregrine falcons and long-billed dowitchers. More than 35 species of warblers also sing in the trees here. The refuge is home to some of these species favorite and most colorful snacks—over 300 varieties of butterflies have been seen throughout the area—that's half of all the known butterfly species in the United States.