Puzzle n°47 (*) - Tits in the garden

great tit (parus major)

With spring returning, cats love to look at the bird antics from the window... This morning, I looked with them and saw several species of tits in my garden : there were great tits, blue tits (smaller but with a strong character), and a group of long-tailed tits.

blue tit (cyanistes caeruleus)

All of a sudden, a noise caused 5 great tits to fly away. But 3 of them soon came back.
Then the neighbour's cat prawled into the garden and 3 long-tailed tits took off.
However, probably used to see him and confident in their flying escape abilities, very soon 2 of them came back too.

At this moment, I observed that there were exactly 12 tits in the garden.

How many long-tailed tits could there be at most at the start of my observation ?

long-tailed tit (aegithalos caudatus)

... I'm giving up...