Sure absolute size doesn't matter. But what about number of neurons or neural connections? I'd be curious what the actual studies say.

The article hinted at this: "African gray parrots, which can identify shapes and even count, as well as corvids, which have an equivalent number of neurons to some primates and, it is suggested, may even be self-aware."

Comparing brain size vs intelligence across species seems weird since neuron size/density differs so much.