Over the last 5 years the difference is noticeable, the last 2 is mind boggling and super scary. At least here the bird variety is still really good but I don't expect that to be the case next year. In fact I think the birds of prey variety and numbers is still increasing as well as ducks, I've seen more ducks this year than I can ever remember around here.
Your broad spectrum idea is most likely the culprit which explains my 2 year observation. Since the current administration relaxed the enforcement of marginally sufficient regulation 3 years ago an already bad situation fell off a cliff.