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.
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