Google Scholar has released a new feature that lists “Classic Papers: Articles That Have Stood The Test of Time”. I am very pleased to see that a paper that I was happy to co-author with late Niclas Jonzén is among the classics, as the fourth most cited publication about birds published in 2006.
In 2005 I published my first ever peer reviewed paper, which was an analysis of long-term bird ringing data from Ottenby Bird Observatory. The 2006 Science paper was, in some sense, triggered or inspired by this work, and here we expanded and used bird ringing data several Scandinavian bird observatories, in combination with data from Capri in Italy. We could show that migratory birds that spend their winter south of the Sahara responded even more strongly to the European winter weather (which determines the progression of the following spring), than did short-distance migrants. So after a cold and dry winter, spring came later, and migratory birds arrived later.
We already knew that the birds arrived later at the Scandinavian breeding grounds, but in this paper, we made use of the data from Capri, as we argued that the arrival to Italy should reflect the departure from sub-Saharan Africa. The rationale for this is that there isn’t much opportunity to spend time between the two regions, as the birds have to cross two major barriers – the Sahara desert and the Mediterranean Sea. Furthermore, even after accounting for the winter weather, there was a clear trend over time towards earlier arrival, which we argued reflects natural selection for earlier spring migration.