That is fairly standard BBC reporting, as is the placing of non-catastrophist caveats deep within the article, thus:
Whether the trend will cause the birds any long-term consequences is unclear. "In one obvious sense, the consequences are positive," says Dr Buskirk ."That is, as temperatures become warmer, the optimal body size is becoming smaller."But then comes the inevitable editorial comment seeking to nullify the inconvenient:
However, even though the species appear to be adapting to the new climatic conditions, it could still be that their average "fitness" in evolutionary terms, is going down.Regrettably, the Bitchy Boys could not get their source to say so.
But more recent ideas [whose?] suggest that animals might actually be responding instead to something else that correlates with temperature, such as the availability of food, or metabolic rate. "It looks like it might take a while before we know," says Dr Buskirk.
Pretty bird pics, though.