I want to point out a possible connection between recent work that’s noticed dramatic declines in Germany’s insect population and recent work that’s noticed dramatic declines in England’s songbird population.
A good guess is that the declines in insect populations are due to increased use of pesticides, or perhaps more effective pesticides in farmlands nearby. A good guess at the decline in bird populations is that there are fewer insects to eat. These days, farming in Germany and the UK are governed by the same environmental regulations, so it’s a good bet that England’s insects are disappearing also.
What does this all mean? Nobody knows yet, but things are changing rapidly enough that we’ll find out in about 20 years. [It probably won’t be especially good news, because our farming is adapted to our current ecological situation, so changing the ecology — at best — means changing our farming practices.]
In practice, this is a good reason to have fewer kids and to eat vegetarian. [Just to be on the safe side. Remember that cows are very inefficient at turning plants into cow.]