SBG, Mine was older than yours-- it didn't have the fluffy down anymore. It was consistently brown. Yours looks like the breast is lighter, and on my monitor, it looks more dark brownish-black. It doesn't look like a sparrow to me. I should have paid attention to the beak, then I'd have realized it was old enough to fly... I left the door to the backyard open, and somehow it got out when I wasn't watching. Now, instead of a bird in the house we have flies. :-(
QNS, I can identify with you. We have plenty of mosquitoes too besides the flies.