Not an expert, but I do not think that you need an evolutionary explanation: birds are often not stupid, and can simply observe that nests with more cigarettes have less parasites.
Do birds spend time observing the nest of their peers? AFAIK the only nests they care about are their own (though I'm definitely not an ornithologist, I'm mostly ignorant about them in general).
But that's the beauty of Darwinism, whether the information is stored in the genes or in their culture (memetically) doesn't matter, the selection/amplification process is the same.
We know they're capable of passing complex information onto each other. What "a bad man's face" looks like for instance, I'm sure some of HN has seen the documentaries on their abilities.
I wonder if they choose nesting material based on insulation properties also. Cigarette stubs are probably great for stuffing into cracks and it is known that plugging air gaps dramatically increases whole house/nest insulation value.
Yep, same way AlphaGo Zero learned to play. It evolved, generation by generation, by selection. People think an agent can't solve a problem unless it has full understanding, but that's not true, selection based on fitness can do it.
Cue fun time with etymology: understand translated to Latin and back yields support, which is significant, kinda, because support vectors are one model of machine intelligence, while DNA is basically a vector, in terms of transcription, or a matrix even, looking closer at the base molecules.
disclaimer: I have n o idea about support vectors, to be honest
Support Vector Machines (SVMs) are a classification technique that was in vogue before 2012, with great results for smallish problems. It's still useful today, but less talked about, I mean, it's just assumed as common knowledge.
i'm wondering if 15-25 generations (that's approximately how many generations of garden birds were there since the invention of the cigarettes with filters) are enough for evolution to actually show this trend here
Tangentially related - there was the russian experiment on fox domestication that had decent success in selecting for "tameability" with just 3 generations.
I think some birds are actually pretty smart and can learn by imitating other birds, so it's a cultural thing. All it takes is one bird to discover it.
Take a look at this video: "Crow uses a vending machine". It was an experiment where they trained crows to collect coins and put them into a vending machine for a few grains.