Of Birds And Fish

Spent some time gazing at my ex-neighbour's pool today¹. Spotted some cute birds (sparrows?) trying to poison themselves with the ex-pool water. They seemed to be enjoying themselves, chirping along happily, when suddenly this mynah stopped next to them and started squawking at them. Scared them away. And started to poison itself too, of course, happily.
Led me to think, do birds share a common language? I mean, there are so many different species of birds, do they share similar 'words' in their various 'languages'? Or is it the tone in which something is said that puts the meaning across? Like when you say 'kan ni nah bei chao ji bai', a non-Hokkien person will still sort of get you and back off? But humans have like so many facial muscles to contort and distort, I don't recall learning about the various maxillo-facial muscles in the common bird?
Hmm perhaps an ornithologist can enlighten me.
(Perhaps you'd like to take a look at this if you're interested/bored)

And oh visited my uncle's house for dinner tonight. Apparently his koi do backflips in the water like dolphins do. I'm serious, I saw two of them (or one koi, twice) do just that while I was there. My cousin kindly informed me that yes, they do do that quite often.
And I thought only dolphins possessed the necessaryintelligencee to get bored of swimming and think of acrobatic tricks to do to entertain themselves.
But come to think of it, backflips should be quite fun for bored fish. Just imagine yourself as a fish - when you're doing a backflip out of water, you're actually depriving yourself of oxygen for the very few seconds you're in the air. Should be kinda like the adrenaline rush you experience when you bungee-jump?
Anyways. Perhaps fish (in general) are smarter than we think they are.

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¹My ex-neighbour's house is currently un-occupied. It has a pool. Or what used to be a pool. Now the water is green and somewhat murky. I'm sure if I decide to be civic-minded and release some fish into the ex-pool (to prevent the growth of mosquito larvae, of course) it'll be an interesting case study for primary school science students. I can just imagine the title : A Semi-Artificial Water Habitat.