Chestnut-backed Chickadee, Poecile Rufescens

Day 218: For years, I was jealous of photographers who captured images of chickadees sitting on peoples' hands, perching on a camera lens, taking seeds daintily from someone's fingers. For that matter, I was jealous of people who could get close to chickadees anywhere, let alone make personal contact. I had chickadees galore in the shrubbery opposite my home, on the other side of the road, but none ever seemed to venture into my yard. I planted bushes and trees to provide better habitat for them, and my efforts were finally rewarded a few years ago when the first Chestnut-backed Chickadees showed up, two of them, and as it turned out, they were a pair. My yard population grew. Then one day, I spotted a Black-capped Chickadee in the contorted filbert. I was overjoyed. After a close approach by one of the Chessies, I decided to hold Chickadee Training to see if I could get one to accept seed from my hand. It happened quicker than I had any right to expect, and soon I had them arguing over who got to sit in my palm, who had to remain on my wrist, and who got to go down inside the canful of seeds under my arm to eat in leisure. But being a scientist, I couldn't help but notice one important thing: the birds who were most comfortable with me were almost all Chessies. The Black-capped 'dees would fly in as if they were going to land on my outstretched hand, but almost invariably decided to retreat to the safety of the filbert. Some would occasionally perch on the feeder beside me, but on the rare times one of them would perch on my palm, the contact lasted only a few seconds. On the flip side, the Chessies would let me walk around while carrying them, and sometimes I'd have to hoist one out of the can if I wanted to go back inside. This raises a question I will probably never be able to answer: Why is one species shy and the other friendly? What pressures could have resulted in such different behaviours in two very similar birds?