Originally I was going to cry about how terrible and annoying the birds in fractals are but since I know it'll kind of be pointless and contribute nothing and I know they won't be removed, I came up with something that, at least for me, can help me tolerate them. Right now, I cannot stand them (I despise them) and I think their spawn numbers have been increased since they came out, but I could be wrong on that one.
My suggestion for them is: leave the blind they do - BUT remove the damage - it can be really troublesome in T4s; especially Siren's Reef + birds. It's too much.
As for Siren's Reef, in T4, at the moment, there are just too many adds, which also have a lot of HP - mostly at the last boss fight. So you combine all of those AOEs + Adds + Birds (and in some cases No Pain No Gain as well) and it's just the worst. Like, fractal 99CM is easier than that, at least in my opinion. To top it all off, stability doesn't work on the AOE that pushes you off the ship into the water where you get tons of condis which stack extremely fast and do a lot of damage. I'm fine with the damage, it is T4 after all, but there's no way to counter the pushing away thing given how many things you have to dodge.
My suggestion for Siren's Reef is: either remove 1/3 or half of the mob numbers on the last boss (Captain Crowe) and make the AOE that pushes you off the ship be counter-able with stability.
Another idea is, if you still want to have all of those numbers, to at least reduce it to "normal mobs + veterans" instead of the current "veterans + elites".
On the side note, if it's of any importance, I've noticed that FB boon + Revenant seem to work better for this specific fractal than Druid+Chrono, at least with PUGs.