Several species have gone extinct in my garden today but then have recolonised naturally. Yes, that's a daft thing to say because the smaller the area the more likely a species is to disappear and then return. Extinction in my garden is trivial, extinction on the planet is much less so. But where do you draw the line?
An excellent example of using more local extinctions in a very good way to make a point is the Plantlife report Where have all the flowers gone? which looks at county extinctions of plant species to demonstrate the ongoing loss and decline in a large number of plants - some of which used to be very common. Plantlife document the county extinctions of species. And my current county of residence, Northamptionshire, is the county with the fastest rate of loss of species - 1.4 species go extinct in Northamptonshire each year in the period 1930-95.
But Plantlife used the county extinctions to illustrate the general loss of plant life, not to claim that the loss of a species from a man-made political designation was particularly significant. And we should always be careful about bandying around the e-word, extinction, when we are talking about limited areas. I know that we, the RSPB, do it sometimes, often when talking about the potential loss of the hen harrier from England (there are a couple of handfuls of pairs these days) when there are many more in Scotland (and Wales, and Ireland, and the Isle of Man, actually),
Just as some species just sneak into this country, and are always rare here, even if they are abundant elsewhere (eg red-necked phalarope at one end of the UK and Savi's warbler at the other), some other species just fail to stay in this country, and go extinct, even if they are abundant elsewhere ( I guess Kentish plover and snowy owl might be examples). Such comings and goings are even more likely to happen, and less likely to be of conservation significance in smaller areas. That's why we shouldn't get too hung up on the multiple local extinctions that happen in my garden every day.
A love of the natural world demonstrates that a person is a cultured inhabitant of planet Earth.
Local extinctions do matter because they are pieces of a jigsaw. When I moved to this address 20 years ago we had a flock of 10+ sparrows; 10 years ago they disappeared. Trichomonosis has reduced the greenfinch flock from 20+ last winter to a lone male this winter. As the Big Garden Birdwatch slogan says: 'Every bird counts'