- One of the rarest birds in the world. Total population size (as of 1990) approximately 250 birds, with 50 individuals on Champion (9.5 hectare islet) and 200 on Gardner-by-Floreana (about 81 hectares).
- Critically endangered because of small population size and limited geographic range.
- Extinct on Floreana, its original primary range. Observed on Floreana by Darwin in 1835 but extinct there since about 1880. Probably cause of extinction was predation by introduced black rats, Rattus rattus (Curry 1985, Grant et al. 2000); predation by introduced cats and habitat degradation by goats may also have contributed. There are no rats on Champion or Gardner.
- Fossils from lava tubes on Floreana confirm former inhabitation (Steadman 1986).
- Cooperative breeder, with up to 8 adults living in group territories.
- Up to 2 pairs breeding at separate nests (with occasional joint-nesting) in each territorial group.
Islota Campéon (Champion), viewed from the west. This 9 ha islet, just 733 m away from Floreana, is one of one two islands inhabited by Mimus trifasciatus.
Female Mimus trifasciatus incubating eggs on Champion.