Many thrushes are numerous and secure. Others are the subject of intensive research, such as the song thrush in Britain, where numbers have fallen dramatically in recent decades in some areas. The problem appears to involve the survival of fledged chicks and the ability to produce a second brood. Some habitats, especially intensive farmland, have too few nest sites and too little food for a pair of thrushes to rear enough young to replace themselves when they die. Nightingales in Britain are declining, primarily through habitat loss and neglect, but numbers remain high in much of Europe.
Other species are genuinely super-rarities. The Seychelles magpie-robin was pushed to the brink of extinction as its habitats and food supplies were reduced, and introduced predators took their toll. Coconut plantations replaced natural forest, cats and rats caught adult and young birds, nest sites and big insect food disappeared. Only an intensive campaign has achieved a recovery.
The Usambara robin-chat (Alethe montana) is restricted to a tiny area of one Tanzanian forest that is subject to clearance for agriculture and tea plantations. Several island species are at risk from habitat loss compounded by the effects of in troduced cats and rats while others such as the Comoro thrush (Turdus bewsheri) that, despite their very restricted range, remain common. The kamao (Myadestes myadestinus), common in Hawaii a century ago, and the olomao (M. lanaiensis), also of Hawaii, are both probably Extinct, while the omao (M. ob-scurus) occupies less than a third of its past Hawaiian range and is greatly reduced in numbers. The puaiohi (M. palmeri) is Critically Endangered. These are a sad reflection of the inability of conservationists and governments to save the several endangered species on these magical islands.
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