The water thick-knee (Burhinus vermiculatus), or water dikkop, name derives from the bird's thickened tarsal joints. Water thick knees are associated with warning both the hippopotamus and Nile crocodile of impending danger. Water thick-knees are mainly active at night and are often seen just standing or sitting during the day on river and lake edges. The white wing bar distinguishes it from the Senegal thick-knee. The Water Thick-knee is monogamous unless its mate dies.