There's one reason not mentioned - habitat loss, be it caused by urbanization [1] or by land consolidation ("Flurbereinigung") [2][3].
It used to be the case that rural areas were splintered into many small farms, with bushes being used to mark borders, and these bushes in turn provided harbor and food for insects and cover for small rodents and other mammals.
"Thanks" to mechanisation however, which prefers large uniform land because thats easier for ever larger machines to process, a lot of these splinters were consolidated together and so there is nothing left to support any wildlife, be it insects or small animals, which in turn also causes bird populations to drop - when there are no mice because they don't have any place to build their nests, the birds don't have food as well.
Those changes to the rural environments started getting made over a century ago, with horse drawn combine harvesters dating to the 1820s-1830s and self-propelled ones to the 1910s; while the insect decline became noticeable this century.
Now sure, the causes could be multipliers, insect_pop = base * (cause_0 * cause_1 * …), or even exponential, insect_pop = 1/e^(cause_0 + cause_1 + …), so I'm not saying none of that stuff matters, but also there's definitely something nee.
jmclnx•12m ago
Plus I heard somewhere song birds are declining due to this apocalypse.
But mosquitoes are not declining, the one insect I wish would decline real fast :)
The windshield test is somewhat deceptive as improved aerodynamics plays a role, but the difference is still quite noticeable when driving around in a classic car.
mschuster91•20m ago
It used to be the case that rural areas were splintered into many small farms, with bushes being used to mark borders, and these bushes in turn provided harbor and food for insects and cover for small rodents and other mammals.
"Thanks" to mechanisation however, which prefers large uniform land because thats easier for ever larger machines to process, a lot of these splinters were consolidated together and so there is nothing left to support any wildlife, be it insects or small animals, which in turn also causes bird populations to drop - when there are no mice because they don't have any place to build their nests, the birds don't have food as well.
[1] https://www.uni-wuerzburg.de/en/news-and-events/news/detail/...
[2] https://www.riffreporter.de/de/umwelt/flugbegleiter-umfrage-...
[3] https://naturschutz-initiative.de/aktuell/neuigkeiten/landwi...
ben_w•6m ago
Now sure, the causes could be multipliers, insect_pop = base * (cause_0 * cause_1 * …), or even exponential, insect_pop = 1/e^(cause_0 + cause_1 + …), so I'm not saying none of that stuff matters, but also there's definitely something nee.