The evolutionary effects of bird tables

[Africa]

There is a very interesting research paper coming up about Blackcaps. German Blackcaps belong to two groups, one of them winters in Britain, the other group in Spain - the traditional wintering ground- , and they seem to be diverging genetically. The most interesting bit is that the migration to Britain seems to have started only since the 50-60's when feeding the birds became commonplace. So, next time you put your food out for the birds, know you are influencing evolution, and possibly, speciation into a new blackcap species!
More details here

[SheffieldLass]

Is it just conjecture that it is due to feeding the birds? My overwintering blackcaps don't go near my feeders. They do go for the fallen apples and the ivy berries though. I had understood that it was probably due to the milder winters recently that the numbers overwintering in Britain had increased, and that the big increase has been in recent years. It would be interesting to have an idea of the numbers over the decades.

Back in the 50s and 60s the types of food put out for the birds was very limited. Scraps mainly, and not by many people either. They may now be doing well because of the high quality foods that are put out by many people. And because we've only had one slightly severe winter in the last 20 years .....

[Hedera]

I get blackcaps every year and they only eat the honeysuckle berries; never seen them on feeders. They have pecked at apple pieces though.

[aeshna5]

Blackcap habits have definitely changed + believe they are showing early signs of speciation, but I don't believe bird tables have much to do with it!

[Jenny W]

After all, the supplementary food provided by humans in gardens is only replacing the natural seed food resources lost through changes in farming practices - the birds are just feeding in gardens instead of farmyards and wheat fields!

[Africa]

I haven't read the original paper, but I expect the authors to suggest bird feeding to have played a role - not directly to have been responsible- given the coincidence between the change in migration patterns and people bird feeding. Of course it is speculation based on correlation, but I find the hypothesis interesting. Studying in detail the feeding patterns of Blackcap in their wintering grounds (including any countryside Blackcaps there might be) might shed light into this, as there might be some other change that has affected their likelihood to survive British winters.