Despite having several bird feeders near the house that are keep stocked with bird seed and fat balls, I have several tits (Great Tits by the lack of blue on them) that seem to delight in tapping on several of my windows.
I can’t see any insects on said windows, so I don’t think they’re looking for food.
Are they casing the joint for some nefarious avian activity or are they just a bit dim?
Never experienced this behaviour in years of feeding wild birds near the house.
We had leaded windows back in UK and tits used to cling to the lead and tap, tap, tap…
they didn’t even mind when I tried taking photos…
Are they seeing reflections of themselves? If so, it’s aggressive behaviour - pecking at a rival.
We had this a couple of years ago, there would also tap on the wing mirrors of the car - so as @SuePJ suggests I think it is aggressive bahaviour.
I’m reasonably sure they’re seeing their reflections - we often have that happen here, and also the birds walking back & forth on the windowsill.