It was storming that night. I live 30 miles from Beebe. I believe there was also hail in the area, but I could be wrong about that. Add fireworks to the mix (but I doubt this, Beebe is a small town) and you have stressed birds flying at night, in the presence of updrafts, freezing rain, lightening, high winds, hail. There were also tornadoes associated with the storm.
You're right, birds normally don't fly at night. But when stress is applied, individuals do things they normally don't do, which is most likely what happened in this occurrence. I must say, that the birds were in fact flying at night. If they weren't flying at night, then how did they fall from the sky during the night? The government dropped them from planes? Chemtrails? The Russians did it? No, I know: Jay-Z and the Illuminati are certainly responsible.
What science? That facts are that mass kills occur very frequently. I honestly wouldn't waste my time conjuring up conspiracies about this.