For a topic that focusses on a very UK-based issue, one could also ask if this study was so good why it ended up in an American-based journal, rather than any of the respected UK journals.
Not good enough to get through UK peer reviews? Reviewers far afield might conveniently be less aware of failings in your data, such as urbanisation and bird data quality realting to the UK, etc.
You're clutching at straws when you start suggesting that the overseas journal is obviously the last refuge for an allegedly shoddy study. The Auk is a highly respected journal, and a quick glance at it's editorial committee will reveal that, whilst having a heavy US / Americas bias it includes members from such 'shonky' institutions as the Max-Planck Institute in Germany and Australia's CSIRO. It is a world class publication.
Regardless the actual reviewers will, as far as practicable, have been selected to have the background to be able to properly review the subject of the study and / or the methodologies used and might well have been English for all you, I or C P Bell know.
I'm not sure what makes me sadder on this thread. People's disrespect for science, or C P Bell's disrespect for people :-C