Alright, I think I will go for an 'attack', though this one is more of highly aggressive scouting/resource raiding. We need any advantage we can get, and if we can trigger a battle between two enemies that would be advantageous.
Alternatively, get confirmation that the Giant Swarm are gone, and we don't have to worry about them.
[X] Lead an attack; Plan: Remember those giant guys?
-The Swarm hasn't sensed so much as a scrap of chitin from the Giant Swarm ever since the Birds exploded in number. Did the Birds devour them for biomass? Or are they still around, and if so, can they be useful?
-Send all the zerglings out towards where the Giant Swarm was, using strength in numbers and speed to punch through any intervening birds.
-If the Giant Swarm is still there, launch a token attack (maybe kill a drone or two), then retreat in the direction of the Bird nest in an attempt to draw the Giant Swarm into attacking the Birds, hopefully weakening and distracting them.
-If their next is destroyed and empty, grab any minerals, gas, or biomass that remains that you can and return home with it, killing any birds along the way.
-If their nest is destroyed and occupied, consider the strength of whatever is there; if you think you can take it, kill it and drag the Essence-rich body(s) back. If it looks strong, try to lure it to the birds.
-Regardless, survival is to be aimed for, but at least some deaths are expected.
-The Queen will stay near the home hive and hunt any bird scouts that get too close while staying safe.