the thick-knees are a group of largely tropical waders in the family burhinidae. they are found worldwide within the tropical zone, with some species also breeding in temperate europe and australia. they are medium to large waders with strong black or yellow-black bills, large yellow eyes and colorful plumage. despite being classed as waders, most species live in arid or semi-arid habitats. there are 9 species worldwide and 1 species which occurs in azerbaijan.