Natural phenomenon? Riiiiiight. I'm not an expert by any means, but I cannot believe that's even remotely "natural." LOL
That being said, do you know if authorities in Austin, TX ever found out what killed all of the birds in downtown Austin yesterday? THAT is pretty freaky too.
Massive fish kills often occur naturally, why would birds (or any other animal) be any different? As various diseases and organisms mutate sooner or later strains occur that cause mass deaths in various species. Nature changes, cycles, and adapts.
So who knows what this is and if it is natural or tied to human actions (though in some ways it is a bit odd to consider humans to be outside of nature.)
They opened the streets at noon after issuing the statement they are testing birds but haven't a clue as to why. For a while they were saying it was the weather. Sure, there was a feakish drop in temperature in the six block area and no where else.