Mimus trifasciatus survives in low numbers on Champion and Gardner-by-Floreana, 2 islets in the Galápagos.


  1. Black rats, Rattus rattus:
    • probably caused the extinction on Floreana
    • are present on islets near the 2 breeding islands and there is a risk of accidental introduction.
  2. Unusually dry La Niña years:
    • correspond with higher adult mortality
    • are increasing in frequency. This is thought to be driving the current decline.
  3. Diseases. Floreana mockingbirds are affected by:
    • Philornis downsi, an invasive parasite
    • avian pox virus. This is thought to be responsible for the increased mortality on Champion during the 1982-1983 El Niño event.
  4. The smooth-billed ani Crotophaga ani:
    • is known to prey on other bird species on the archipelago
    • has been seen on Champion
  5. Loss of genetic diversity:
    • caused by the loss of immigration from the now extinct Floreana population.
    • has raised concerns for the long-term survival of the 2 remaining populations.