Why is it that such intuitively obvious observations somehow never get taken up by the scientific community?My backyard in Lincolnshire was always full of Blue, Great, Coal and occasionally Long-tailed Tits. Greenfinch, Chaffinch with very occasional Redpoll and the odd Bullfinch. Rarely Goldfinch. Now it seems it's all Goldfinch if my sisters garden is anything to go by. Years ago I used to have to clean the squashed bugs from the front of the car every week or so. No bugs, no birds.
Every older driver knows that the insect population has crashed, their clean cars prove it.
Good luck trying to get a study published on the topic.