Bizarre bunnybird behavior. What the hell are these birdbrains trying to do?→[More:] For the last three days, these two birds have been pestering me at work. They always show up together; one of them, the more quiet one, has a dark, almost black body, with a lighter colored head. His (?) mate is slightly smaller, with kind of speckled color.

They have been appearing right outside both of the windows in my office. They land on the outside sill, and look in. Movement inside and even knocking on the window fail to scare them. They peck at the window, sometimes hard enough to push themselves backward. The smaller one that I'm guessing is female will, every 15-20 seconds, make this weird twittering noise while puffing up. The male will not make the noise, but will puff up in sympathy with the female. Occasionally, they'll get into a tiff and peck at each other. They'll sit out there for up to a half hour at a time, then fly off for parts unknown, only to reappear an hour or two later and repeat the performance.

What the hell???