As they stated "
there is little evidence that the change is harmful to the birds. ".
Maybe it's even helpful. Could they fly a little faster, hide a little better, survive on less food?
The first question that I asked when reading the article is "how many birds were killed by these scienti .... errr, I mean, their "slave labor" grad students, while capturing 480,000 birds?".
PLEASE DON'T SQUEEZE ME HARD!

Of course they treat it as a fact that it has gotten warmer in the last 48 years. After all, there is consensus.
Just for kicks, I found the nearest NASA GISS's own temperature monitoring station to the bird collection site at Carnegie's Powdermill station. Uniontown. It makes one ask what if they started the study in 1930? Would it mean a darn thing?
http://gallery.surfacestations.org/main.php?g2_itemId=41628