Noises?

 The last two days I've noticed some odd noises. Yesterday I really picked up on one, it's what sounds like small stones falling behind me.  Not great big thuds, just like a chipping hitting the pavenment behind me.

 Now I know that sounds like I'm loosing my marbles but I am hearing it.  At first I just thught is was something falling from a tree.. a twig or something, then I heard it again.  Now it's not all the time, just now and then.  I did wonder if it's a stone in my shoe heel (had that before) but I checked my shoes and they are fine.  I can only assume it's something in my coat (theres nobody around when it happens) and I'll have to try a different jacket and see if it's still there.

 The other noise it much easier to explain, but still odd, it's birds tweeting after dark.  Most birds go quiet after dark, but for some reason I'm getting quite a lot of bird life sounds when I'm out and about, and this is long after full darkness.

 I do wonder if the new "daylight" streetlights may be confusing our feathered friends?  But it's just a guess.