Personality characteristics have been extensively studied in great tits. Individual great tits differ in the way they explore a novel environment and, at the extremes of the variation, may be assessed as ‘slow’ or ‘fast’ explorers.
Now that I have your attention, let me just say that this is an excerpt from an article in The Royal Society's Proceedings B which publishes research articles within the realm of the biological sciences.
This article, entitled "Personality matters: individual variation in reactions of naive bird predators to aposematic prey," studies the affect of the bird's personality on its predatory behavior when exposed to a brightly colored firebug for the first time.
It's a quick read and not all that riveting, but if you like reading about great tits then this article is safe for work.