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 loss of hedgerows, a move to sowing crops in autumn rather than spring, and possibly the increased use of pesticides. These changes may have reduced the availability of food and of nest sites. In gardens, the use of poison bait to control slugs and snails may pose a threat. In urban areas, some thrushes are killed while using the hard surface of roads to smash snails. The song thrush's characteristic song, with melodic phrases repeated twice or more, is described by the nineteenth-century British poet Robert Browning in his poem "Home Thoughts, from Abroad": That's the wise thrush; he sings