Spent most of today fretting about whether to declare war on the six eyed bears that have set themselves up on the doorstep of my glorious avian communist utopia. Look at these pricks (I'm blue, they're light green):
On the one talon: They're religious extremists. They will genocide us if they think they can possibly get away with it. Planting an ursinery next door to my fledgling outpost is an act of naked aggression, and frankly suicidal given the relative size and position of our empires. I could probably crush them right now.
On the other: My populations are mostly hippy doves who deplore war, even against Wombat ISIS. Popularity is a major factor in Stellaris and I've so far been playing a ginger balancing act with it. I'm not really in any dire straits, and can probably continue to outgrow them. It's possible/probable they'll get involved in a destructive war with one of the other races vying for space here and exhaust themselves.
Difficult, when all you want to do is erect vast concrete nests on alien worlds.