A woodpecker paradise, and 1000 birds
A little-known fact about Prague is that the city, like much of the Czech Republic, is a paradise for woodpeckers (and for their afficionados). Even city parks such as the Petřín Hill and Královská Obora parks are rich in mixed woodlands which attract at least six species of woodpecker, as well as their congeners such as Nuthatches and Treecreepers. The Middle Spotted Woodpecker is a central European species which requires mature deciduous forest. In the Královská Obora park today, a photogenic male perched for some time on a the trunk of an oak tree.
According to the eBird database, this woodpecker was the 1000th species I have recorded in a total of 1900 checklists. This is not exactly a list of species I have seen, since it includes some 'heard only' species such as owls, and excludes various birds which I saw before the eBird era and did not record accurately enough to enter in the database retrospectively. But when I began using eBird to record sightings in 2017, 1000 birds seemed like a reasonable goal. At the time, it was agreed that there were around 10000 bird species in the world, so that 1000 would be a representative sample of 10%.
Now for the interesting part. Despite ongoing extinctions, the number of known bird species is rapidly rising. Thanks largely to genetic sequencing, it has become clear that birds which look alike do not necessarily belong to the same species, and vice versa. 'Cryptic species' appear similar but do not interbreed because they are separated by behaviour and vocalizations as well as geography. The Chinese Blackbird, for example, looks much like the Eurasian Blackbird but differs in its vocalizations and behaviour. The Lesser Sand Plover no longer exists, but turns out to have been an amalgam of two similar-looking species that are not particularly closely related, having diverged around 2 million years ago. Even the familiar Eurasian Wren is likely to be 'split' into several species.
As a consequence of these 'splits', a recent estimate suggests that there may be around 18,000 bird species -- almost twice as many as was believed less than ten years ago. This is a valuable lesson in what Konrad Lorenz called scientific humility: all knowledge is provisional, and students of the natural world should not be too confident about what we think we 'know'.
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