"I have wondered if it would be possible to train crows to pick up litter
and fly it to dumpsters in parks or near roads and reward them with food.
They are certainly capable and if the reward was large enough they would
probably be motivated to do so."

My housemate, who used to volunteer at the Oregon Zoo, notes that they had
a raven there who was trained to pick up sample recycling items (tin can,
yoghurt cup, etc) and deposit them appropriately. I think the subtext was
"if the bird can do it, so can you." No comment on whether humans are
smart enough to do the same... the zoo here in Seattle (Woodland Park Zoo)
has a Turkey Vulture who (with moderate success) can put a yoghurt cup in
a recycling bin.

Kelsey Byers (Wallingford/Greenlake, Seattle)
Department of Biology
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kjbyers at uw.edu
(978)460-3581
KB1ONA