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"
White-necked thrush approach members of the "phaeopygos" group in both plumage and colour of bill. If the two groups are split, the common name rufous-flanked thrush has been suggested for "T. albicollis", with "T. phaeopygos" retaining the common name white-necked thrush or being renamed grey-flanked thrush. White-necked thrush The white-necked thrush ("Turdus albicollis") is a songbird found in forest and woodland in South America. The taxonomy is potentially confusing, and it sometimes includes the members of the "T. assimilis" group as subspecies, in which case the "combined species" is referred to as the white-throated thrush (a name limited to "T. assimilis" when