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 include parks, gardens, coniferous and deciduous woodland and hedgerows. Birds of the nominate subspecies were introduced to New Zealand and Australia by acclimatisation societies between 1860 and 1880, apparently for purely sentimental reasons. In New Zealand, where it was introduced on both the main islands, the song thrush quickly established itself and spread to surrounding islands such as the Kermadecs, Chatham and Auckland Islands. Although it is common and widespread in New Zealand, in Australia only a small population survives around Melbourne. In New Zealand, there appears to be a limited detrimental effect on some invertebrates due to predation by