I am impressed by the questions, studies, and thoughts of Dr. McGowan and his associates. It really gets me thinking! I usually see city crows trying to get into fast food bags. Their perseverance is strong in getting to whatever might be in the bag.
In the 1980s, I used to sit on my porch near dusk and watch crows pass over head heading back home. It was a fairly constant flow considering that I live in Southern CA. Over the decades I noticed that there were fewer and fewer instances of seeing/hearing "streams" of crows at night or morning for that matter. Just recently (over the last 5 years), I have once again noticed crows heading west toward the evening. Just a couple of days ago, around 4 pm, there was a nice flow of crows heading west. What happened to the populations from the 1980s and why are crows now making a comeback even with urban sprawl?
I used to wonder and still do wonder where there home might be...
I noticed that a crow's feathers seem to be really dark black whereas some of the other birds have an iridescent sheen to their feathers. Like other mentioned, I too noticed the black eye. I did get tricked one time though relying on this feature!