In the last post, I discussed two recent scientific articles that presented depressing and convincing evidence of broad declines in the birds of North America. I want to follow that up with a discussion of a couple of recent articles on insect declines.

The fate of birds and insects are tightly linked. Some birds like flycatchers, swifts and swallows capture insects on the wing. Others like cuckoos, warblers and vireos glean larval insects from leaves. Nectar-feeders like hummingbirds and seed-eaters like sparrows capture insects as a great source of protein for their nestlings. Many insects are critical components of food webs on which hawks and owls depend.

A review by David Wagner showed that flying, ground and aquatic insects are declining worldwide and some extinctions have been documented. A paper by van Klink and colleagues compiled data from 166 long-term surveys. They found that terrestrial insects are declining by 9% per decade. That is frightening!

References

van Klink, R., Bowler, D. E., Gongalsky, K. B., Swengel, A. B., Gentile, A. and J. M Chase. 2020. Meta-analysis reveals declines in terrestrial but increases in freshwater insect abundance. Science 368: 417-42

Wagner, D. L. 2020. Insect Declines in the Anthropocene. Ann. Rev. Entomology 65;457-480.