Science sometimes takes awhile as data is analyzed, graphed, etc. Then the research has to be written to an acceptable level to be read by other ornithogist/peer reviewed. (not me and you.)  There is more a detailed paper on his research which the article provided a link.  Since he's doing 10 year increments, the next study, including 2017 is a ways off, though he may has preliminary data. 99% of scientist don't jump the gun on the results of their research.