Hey, Chooks! Okay, it's a great datum! I worked hard on this one -- Immelman made his observations in a European zoo, which -- for an academic based in W.A. -- is flat-out sloppy. Of course we don't count disturbed birds bolting (likely disturbed by farmers spotlighting for roos to shoot)
lol, that is indeed very sloppy.
What I am sure of is: one: I have often seen 'my' birds emerge at dawn from the spot they retired to at dusk, but Two: have never seen an emu grazing at night. And the locals I asked said no: I asked them because if they move at night, they would be hit at night by cars -- as many 'roos are.
I've seen them around dusk and dawn but don't think I've seen them active at night, to the best of my recollection. But most animals will get up to some shenanigans at night time for whatever reason; in this case possibly the emus found the crowds at the zoo distressing so made the most of the night time. I've had a few chooks and other animals that would eat at night instead, often when stressed or unwell. I don't think chooks overall can see in the dark but that said I think one of my hens could, she could navigate an obstacle filled yard with perfect ease at top speed during the blackest nights.
Best wishes.