Lest tobacco manufacturers try to trumpet how compounds in cigarettes help protect urban bird nests from parasites, Suárez-Rodríguez warned at the very end of the article that carcinogens and pesticides in the butts may have negative effects on the birds which we don't yet know about.
I'm amazed at what is being claimed in the headline/description in this article versus what the paper actually has demonstrated (from the brief description in the article/reading the abstract online) - I actually wondered whether the original poster was intending to highlight this disparity.
First, the conclusion of the researchers is that having more cigarette butts in a nest correlates with having fewer parasitic mites, but this article states that chemicals in cigarette butts are already known to repel mites. Wouldn't one expect a correlation here? Of course, it's by no means a given, and experiment is required to bear out this conclusion, but it seems like nobody should come away surprised.
Second, a correlation here is completely independent from the conclusion that "city birds use cigarette butts" as anything beyond building material! It leaves open this possibility but as far as I can tell the question of intent is entirely unaddressed by the current research.
I already know not to expect more from pop-sci research highlights, but I would have though Nature would do better.
It's kind of surprising that a used cigarette butt (as opposed to, say, unburned tobacco) holds enough nicotine to act as an effective anti-parasite material for a nest. It's at least a non-obvious result.
The article linked to another nature article about birds selectively choosing herbs that repel parasites to line nests, and using scent to know when to refresh them.
Given that cigarette butts are effective and that birds are known to pick nest material carefully, the conclusion that birds are introducing them intentionally isn't unreasonable.
Who is surprised? No-one in the article nor the sub-editor's choice of headline suggests surprise.
Where are the sensationalist lines that you see? Apart from the heading, the article is full of questions as to whether or not the birds are doing a modern variation of a previously acknowledged behaviour, from the first paragraph to the second-last. It seems to me that you're reading too much into just the heading, then choosing to be outraged.
Not too surprising, as both smoke, and many different herbs, are natural pest repellents. Bay leaves, lavender, thyme, etc., might do a good job here too, but of course cannot compete with the availability of pre-shredded tobacco bits in the city.
This reminds me of the bird habit of "anting" which consists of a bird applying ants (often with the intent of taking advantage of their formic acid) to their plumage to help eliminate parasites.
I imagine if your diet consists of things like "french fries sitting in a puddle of antifreeze and oil leakage from the side of the road" you could get cancer quite quickly :-)
