Crow flies with thing in its beak. Sees food, drops thing, grabs food. Comes back later, sees more food! Assumes food came from dropping thing (See "Superstition in the pigeon" [0]). Meme spreads among the crows.
No ethics or deep reasoning required. Random rewards lead to irrational behavior.
The final example though, where a Crow returns the camera-lens cap to the family requires some pretty advanced thinking. We know that Crows recognize human faces and expressions, and communicate these facts amongst each other.
Crows / Ravens are the only creature aside from Humans who perform meta-tool use. They can use tools to grab tools to accomplish a goal. In many ways, they're smarter than (non-human) primates, and are probably the 2nd smartest animals on earth.
Birds in general are pretty smart (see Pidgeons, Parrots, etc. etc.) However crows / ravens are on a completely different intelligence level. Crows break nuts by dropping them on the asphalt... timing their drops during red lights so that traffic doesn't hit them.
Besides, gift-giving is seen in far dumber animals than crows. Dogs, Cats, Penguins... they don't have the intelligence of Crows but they understand gifts and social situations.
It sounds like there's a pretty big amount of crows that got in on the "drop gifts for food" program. And a camera lens is well within the range of what a crow would usually be interested in. It doesn't sound unlikely to me that it would just pick it up as any other thing and gift it.
Crows are awesome though, I'm not trying to put down their intelligence, haha. I just wanted to point out that neither deeper reasoning nor ethics is required to explain this phenomenon. One of the researchers in the article said that he had never experienced the gift giving, even though he also fed crows often. That to me makes it more sensible to believe that it's just a meme that developed by chance
That's not what the researcher said. He made no claim to having fed them often (and consistently, which is mentioned as helpful to induce the behavior).
But crow gifts are not guaranteed. "I can't say they always will (give presents)," Marzluff admits, having never received any gifts personally, "but I have seen an awful lot of things crows have brought people.
> The final example though, where a Crow returns the camera-lens cap to the family requires some pretty advanced thinking.
I think the article (and probably the podcast? haven't listened yet) make too big a deal of this. We don't know that the crows realized that the lens cap belonged to those people. Perhaps they just saw it as another neat thing to gift. Perhaps they smelled the family on it, and just returned it to a place that smelled similarly.
I can't, but I have no idea what that's supposed to prove. That animals have abilities I don't? I can't fly, either, or swim in the arctic ocean and catch fish with my mouth.
What amazes me is crows manage to do all this with their beaks. Imagine if they had limbs and hands like monkeys? It would be Rise of the Planet of the Ape Crows.
So, to be clear, you're positing an alternative theory wherein one or more crows learn a behaviour, and teach that behaviour to other crows, who learn this complex concept and repeat the feat while they, too, pass it on.
Kind of painfull that you link to Skinner's (pretty much) only ill-done research; See J.E.R. Staddon for a nice refutation of 'the superstition in the pigeon' experiment.
No ethics or deep reasoning required. Random rewards lead to irrational behavior.
[0] http://psychclassics.asu.edu/Skinner/Pigeon/