A hundred bird species have vanished since 1600, nearly all due to human activities, chiefly habitat loss, overhunting, and introduced predators. Island birds are especially vulnerable. Below are some of these birds, the year each was last seen in the wild, and the cause(s) of extinction.
King Island Emu (Australia). 1850. Hunting and burning.
Atitlan Grebe (Guatemala). 1986. Introduced fish and habitat loss caused by earthquake.
They were imported as fashionable additions to estates, but grey squirrels soon became the main threat to the survival of the native red population.
Native to the eastern half of North America, grey squirrels were first introduced to Britain in the 1870s and are now widely distributed across the UK. With an estimated population of 2,520,000 across the UK, grey squirrels now heavily outweigh their red counterparts, of which, only around 10,000 -15,000 are thought to exist. Although originally imported as fashionable additions to estates, the grey squirrel is noted as the main threat to the survival of the native red population. Being larger than red squirrels and capable of storing up to four times more fat, grey squirrels necessarily stand a greater chance of surviving tough winter conditions. On top of this, competition is increased by their ability to produce more young and live at higher densities. However, rivalry between the species is not the only problem. Grey squirrels are carriers of the Squirrel pox virus, which the reds have no immunity to. It needs only one grey squirrel to introduce the virus to a local population of red squirrels for the virus to take a hold and spread throughout the entire group, with devastating effects. Where a grey squirrel has introduced Squirrel pox, population decline amongst red squirrels is 17-25 times more rapid than through competition alone. It is unclear when anyone was last prosecuted for not reporting a grey squirrel in their garden. However, in 2010 a man was ordered to pay more than £1500 for drowning a grey squirrel. Raymond Eliot trapped the animal because it kept raiding his bird feeding table. After killing it he became the first person in the country to be convicted of cruelty to a wild animal under the Animal Welfare Act 2006. Also seeking to protect the birds in his garden, a former Welsh Guardsman was also prosecuted after catching a number of grey squirrels and releasing them into the wild. Had he simply shot the squirrels dead, rather than opting for a more humane solution, Mr. Hill would have faced no charges. Although the future of red squirrels is uncertain, there are still high numbers present in Scotland. It is also believed that the red squirrel population is stabilising in the North East of England thanks to efforts in both rural and city areas. In a three month study carried out in 2013 across almost 300 woodlands in the north, the number of red squirrels was found to have risen by 7% compared to the previous spring. Results also found that pox-carrying grey squirrels were on the decline.