The roseate spoonbill was formally described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae under the current binomial name Platalea ajaja.

[2] Linnaeus largely based his account on the "Aiaia" that been described and illustrated over a century earlier by the German naturalist Georg Marcgrave in his book Historia Naturalis Brasiliae.

[4][5] The genus name Platalea is Latin and means "broad", referring to the distinctive shape of the bill; the specific epithet ajaja is from the name for the species in the Tupi language as reported by Marcgrave.

They felt the genetic evidence meant it was equally valid to consider all six to be classified within the genus Platalea or alternatively the two placed in the monotypic genera Platibis and Ajaia, respectively.

[14] Generally, the species occurs in South America mostly east of the Andes, and in coastal regions of the Caribbean, Central America, Mexico, and the Gulf Coast of the United States,[15][16] and from central Florida's Atlantic coast[17] at Merritt Island National Wildlife Refuge, adjoined with NASA Kennedy Space Center at least as far north as South Carolina's Myrtle Beach.

[19][14] However, following decades of conservation efforts, and the effects of climate change, the range of the roseate spoonbill has expanded considerably in the 21st century.

It made an historic reappearance 178 years later when a specimen was sighted by a crew that was doing birding surveys on the restricted-access Cat Island Causeway on July 27, 2023.

[24] The bird feeds on crustaceans, bits of plant material, aquatic insects, mollusks, frogs, newts and very small fish (such as minnows) ignored by larger waders.

[24][25][26] In Brazil, researchers found roseate spoonbill diets to consist of fish, insects, crustaceans, mollusks, and seeds, all foraged from limnetic/freshwater habitats.

This habitat specialization, combined with the relative plasticity of great egret foraging behavior, allows the two species to minimize competition during the breeding season.