[jackgolding]

If you read through to a linked article you'll find there is indeed long term health effects to the birds https://www.newscientist.com/article/mg22730341-600-birds-lo...

[undersuit]

I never said there weren't. I specifically worded my comment to suggest that the benefits might outweigh the harm.

[anotherevan]

For instance, if the crows are picking up enough, then there will be less birds using them for nesting material, which is a more prolonged exposure.