I've sketched an approximation of a chart to help us decide...
1 or 2 birds = on trend
3 or 4 birds = complementarily on trend
5 or 6 birds = a little bit keen
7 or 8 birds = getting a wee bit silly
9 birds or above = possibly excessive
...but then there's a glitch in the results and once you hit 21 you're back to awesome!?
Oh look at that, I even have an example of a 21 bird-ed outfit!
Coincidence? Um... no.
What birds do we have here then?
Sadly, I only own a handful of these items myself, so I imagine that would only get me into the "a bit keen" range... more birds needed, methinks!