It is restricted to a captive breeding program following its extinction in the wild due primarily to predation by the introduced brown tree snake.

[3] The mysterious extinct Ryūkyū kingfisher, known from a single specimen, is sometimes placed as a subspecies (T. c. miyakoensis; Fry et al. 1992), but was declared invalid by the International Ornithological Congress in 2022, rendering the species monotypic.

[9] The Guam kingfisher population was extirpated from its native habitat after the introduction of brown tree snakes.

[11][12] In 2023 the Guam kingfisher was featured on a United States Postal Service Forever stamp as part of the Endangered Species set, based on a photograph from Joel Sartore's Photo Ark.

[13] A mated pair of Guam kingfishers can be viewed by the public at the National Aviary in Pittsburgh, one of the participants in the species survival plan.