Following on from my recent question about Wrens (many thanks again to David and Alf for help in resolving that query):-

It has occurred to me that many species of small birds in North America are remarkably similar to European species.  Besides Winter Wren / Eurasian Wren, there are, for example, Brown Creeper / Treecreeper, Chickadees / Titmice, Red Winged Blackbird / Blackbird, Kinglets / gold- and fire-crests and so on.

As I understand it, (speaking as a non-biologist) when lots of species are 'similar but different' in this way, it implies that each pair of species has a common ancestor, but the current species populations have been apart for only a fairly short period of time ("short" by the standards of evolution).

This makes me wonder how this could be - the Atlantic ocean has been there for a long time, as I understand it, and is a formidable barrier to small birds.  I know that migrants do get blown across (hence the autumn gathering in the Scilly Isles), but I'd have thought that the chances of self-sustaining pospulations of many different small birds being blown across are pretty remote.

Perhaps sea levels were lower in the relatively recent past, and this made it easier for birds to "hop" between islands from one continent to the other ?

I am puzzled, and reduced to speculation.  I've had a quick look on the internet, but have struggled to find anything relevant.

Can anyone shed any light on this ?

Many Thanks.

I'm sure that there are a whole host of articles and books written on the subject and there isn't one simple answer.

To take one example, that of the Nearctic vultures, it has been shown conclusively that they are in fact completely unrelated to vultures from the other side of the Atlantic or Pacific but are the result of convergent evolution.

As for most of the passerines listed I am sure that DP is correct and that their origins lie well before the last couple of ice ages when there was at least one land bridge between North America and Europe, and North America and Asia (tits, blackbirds, treecreepers etc are also very common and numerous in Asia).

My simplified understanding was that a lot of species that look similar are a result of convergent evolution so they've evolved to fill a similar niche. I could be very wrong? I understood for example that American wood warblers are related to buntings!

anyway - any yank would be welcome hereabouts

ha - never thought of that!