How big are their brains? Obviously, given their head size, tiny. My impression, therefore, was that these everyday little birds can't be too smart.
That changed when I sat in a cafe drinking coffee and idly watched people come and go through sliding doors.
The approach of each customer triggered an outdoor movement sensor. The doors slid apart to allow people to come through and slid shut again once they were inside. Simple.
Then, as someone strolled in, I noticed an opportunistic sparrow enter too, fluttering in on the man's slipstream before the doors slid shut again. Of course a cafe is avian heaven, its floor and tables scattered with dropped crumbs – at least until human scolding chases feathered scavengers away. Cheeky, I thought.
What happened next amazed me. No new human customers were arriving. But then I spotted a tiny bird, its fragile wings a brown blur as it sped towards me, heading straight for the closed doors – heavy doors, with metal frames enclosing big panes of glass. Just as it seemed certain it was about to smack into the glass and break its neck, the doors began to open and the sparrow had a hand-span gap to speed through. It was in.
Yay, sparrows! How long had it taken, I wondered, for them to learn the trick of using people to open the doors for them. And then, how long had it taken for one smartypants to figure out that they didn't need human triggers at all. They could do it themselves. Some extra-clever member of the flock worked out the exact speed and trajectory necessary to trigger the motion sensor, make the doors open and create the gap that would allow them access.
Once one had succeeded, all of them could play the game.
Some probably died before they got it right. Too fast and a bird would crash and probably kill itself. Too slow and they'd run the risk of getting caught by closing doors. Too high, or too low, and the doors would fail to open at all. Somehow. like human fighter pilots aiming for the deck of an aircraft carrier, they had taught themselves exactly the right approach speed and height to hit the target at the right moment and get themselves safely down.
I didn't stay long enough to see how they exited again, probably simply hopping out at will as the doors allowed people in and out. But I left smiling. There's nothing like seeing one of Nature's smallest and most ordinary birds achieving a level of magnificence. It makes you realise how little we know about even the most familiar critters on the planet.