Matmail: Driving north on 805 one day, I noticed a whole mess of pigeons amping out on the Clairemont Mesa exit sign. There were none on the sign before it or after it Now this wouldn’t be so strange except they are ALWAYS there. Is this some sort of pigeon clubhouse? Who do they choose this spot day after day and not any other sign? It’s very creepy. The thing they make B movies out of. — fsyona, the Net

Dear Matthew Alice: I’ve noticed while driving south on 805 that those freeway exit signs are mostly birdless except for one. The sign that marks the Clairemont Mesa Boulevard exit usually has quite a flock of our feathered friends onboard. Does this particular sign possibly have a birdie foot warmer built into it? What’s your take on this? — Rick W, the Net

Dear Matthew: My wife and I were driving south on Genesee and came to a red light at Clairemont Mesa Boulevard. Looking up, we noticed that the pole from which the light hangs was covered with pigeons! We looked around at all the other poles but found no pigeons. Since then we’ve kept an eye out for other pigeon-covered poles and haven’t found any. We've come up with all kinds of wacky theories involving temperatures of the pole, migration patterns, and even magnetic fields to explain this phenomenon, but we still remain puzzled. — David, San Diego

Expect little from the common street pigeon, the sheep of the bird world. If one gets a good idea, the rest are happy to follow along. It’s strongly instinctive, a protective device for individual birds within the flock and a food-finding advantage. Pigeons descend from European cliff-dwelling birds. They’re happy on high places like phone poles and building ledges. Why those particular phone poles? It’s likely no more complicated than the fact that one landed there one day, the rest followed, nothing bad happened to them while they rested, so they keep going back. They’ll move on at some point They probably have a regular round of food-scavenging spots, and these poles happen to be conveniently located. Habit, habit habit — boring if you want some spectacularly clever story about pigeon behavior, but excellent if you’re training homing pigeons, which are just common street pigeons with diplomas.