Train birder spots cross-channel invaders

Whilst travelling through devon on my way home from my recent Cornish shark expedition (of which more soon) I spied a few largish white birds from my eco-friendly train's (I hope team hummingbird are happy with my choice of transportation) window.

Typically in the past one would see a blurred white bird shape by a pond or river one was travelling past and know it was a swan or aylesbury duck. Those days are gone. A decade or two ago Little Egrets in the UK would draw admiring crowds of twitchers as rare visitors from the mainland. Once a few pairs established a toehold though they took off big style and now are so common in parts as to not warrant a second look. Interestingly cattle egrets seem to be following suit (more on them eventually too). Global warming or are herons simply suited to dispersion? I don't know but since they seem to roost and breed communally I wonder if there needed to be a critical mass of birds to trigger successful breeding that once reached led to a spectacular population explosion. I digiscoped the shot above at Gib Point, Lincs where they are still unusual enough to draw comment. Down south meanwhile I saw 20 or so from my train window.

Whats the moral of the story? Erm...keep an eye out wherever you go for new birds and, erm, use public transport so you can bird safely while travelling and, erm, change happens - it can be good, so embrace it.