So, I had a similar thought to yours, which was that it is not unusual for populations of any animal in the wild to have long term cycles. The idea that this i

So, I had a similar thought to yours, which was that it is not unusual for populations of any animal in the wild to have long term cycles. The idea that this is necessarily not a big issue, though, does not necessarily follow. For example, some (not all) scientists think we have seen a large-scale decline in insect populations due to insecticides being used in ever-larger quantities in North America. If insectivorous bird species are dying of malnutrition, this could be a result of human insecticide (over)use.