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"
Song thrush derives from this thrush. A Russian study of blood parasites showed that all the fieldfares, redwings and song thrushes sampled carried haematozoans, particularly "Haemoproteus" and "Trypanosoma". "Ixodes" ticks are also common, and can carry pathogens, including tick-borne encephalitis in forested areas of central and eastern Europe and Russia, and, more widely, "Borrelia" bacteria. Some species of "Borrelia" cause Lyme disease, and ground-feeding birds like the song thrush may act as a reservoir for the disease. The song thrush is omnivorous, eating a wide range of invertebrates, especially earthworms and snails, as well as soft fruit and berries. Like its relative,