Some birds, especially corvids such as crows, are even more highly intelligent than previously believed, according to a pair of studies in Science. The first study, which tracked neuron activity as crows performed tasks, suggests corvids scan their brains as they solve problems, while the second study focused on the anatomy of pigeon and barn owl brains to determine the way their neurons work, which hinted at higher intelligence.
The original Science articles referenced in this review (click title above) is groundbreaking.  

This research is groundbreaking.” “the discovery that more and more nonhumans seem to have it (consciousness) raises tricky questions about how we treat them”.