The 4th species of flamingo at the Fort Worth Zoo is the strangest looking by far. They are the smallest flamingos and have unusual bills. The brighter pink one is an adult & the lighter ones are immature teenagers. Interesting fact from the Fort Worth Zoo page: "Historically, lesser flamingos have been extremely difficult to breed in captivity and reproduced less than any other flamingo species found in zoos. The Fort Worth Zoo’s bird department developed a new indoor breeding strategy in 2002 that has made the Fort Worth Zoo the No. 1 lesser flamingo breeding facility in the world."
Lesser Flamingo (Phoeniconaias minor)
Fort Worth Zoo