Song thrush thrush recognizes the cuckoo's non-mimetic eggs. However, the song thrush does not demonstrate the same aggression toward the adult cuckoo that is shown by the blackbird. The introduced birds in New Zealand, where the cuckoo does not occur, have, over the past 130 years, retained the ability to recognise and reject non-mimetic eggs. Adult birds may be killed by cats, little owls and sparrowhawks, and eggs and nestlings are taken by magpies, jays, and, where present, grey squirrels. As with other passerine birds, parasites are common, and include endoparasites, such as the nematode "Splendidofilaria (Avifilaria) mavis" whose specific name "mavis"
Chestnut-backed thrush in the UK are participating in the breeding scheme for this species and are being particularly successful. A European species, the fieldfare, was once also known by this name . The binomial name of this bird commemorates the American entomologist William Doherty. Chestnut-backed thrush The chestnut-backed thrush ("Geokichla dohertyi") is a ground thrush species endemic to Lombok, Timor and the Lesser Sunda Islands in Indonesia. The species is rapidly declining and it is already extinct on Lombok and possibly on Lesser Sunda. There are a number of European institutions that hold this species, including: Berlin Zoological Garden, Birdworld, Bristol Zoo,