The Little Egret (Egretta garzetta) has a remarkable colonisation story in the UK, which has occurred rather rapidly over the last two decades. Although common throughout Europe and the Mediterranean, a range expansion into western and northern France in the latter half of the 20th century preceded its establishment as a breeding species in the UK in the late 1990s. Prior to this arrival, it was a very rare sight indeed around the southern coast of this country, attracting about as much attention as a Squacco Heron does at present. However, this range expansion (voiced to be a climate change-driven movement) led to its population explosion in the UK: the first successful breeding attempt was in Poole Harbour (Dorset) in 1996; ten years later there were 500 pairs in 60 colonies, followed by 800 pairs just two years later! You can see an impressive graph by the BTO documenting this colonisation here.
This species hasn't always had it easy: the elegant neck plumes sported by birds in breeding plumage were once sought out for ornamental decorations and fashion purposes, leading to significant population declines in the 19th Century. Indeed, the price for these plumes reached £15 for 28 grams, which is about £875 in today's prices! That made these plumes more valuable than gold for a time! Thankfully though, laws (and tastes in fashion) have since come in to put a halt to this pointless slaughter of such a beautiful bird. Nowadays, this elegant species can be found stalking the shallows in estuaries and coastlines around much of the UK, stabbing into rock pools and mud flats with its distinctive poised gait after invertebrates such as fish and crustaceans.