Dennis wrote:

> It has also become established in the Bahamas, perhaps even
> naturally, and now Florida. It is spreading through that area
> like, as the saying goes, wildfire. So don't worry too much
> about going to Florida to get it on your life list; it'll
> probably be up thisaway before too many years
>

The expansion of Collared Dove, Streptopelia decaocto, peaked in northern
Scotland in the mid 1970's since then numbers have dropped off considerably.
The result is probably poor local breeding conditions, so this begs the
question what was fuelling the expansion ? It would appear, purely
subjectively of course, that the species was "actively" colonising rather than
growing. It may have been related to increases in grain production which
enabled the species to spread so rapidly. The decline may also be in part due
to changes in agriculture.

The species is thought to be sedentary in the UK, however friends who work
out in the North Sea regularly reported seeing the birds out on oil rigs,
sometimes as far a 200 or so miles NNE of Shetland, roughly 63-65 degrees N.

Any similar species expansion over here ?

Stuart MacKay