Reading this paper carefully actually left me feeling quite skeptical about how species population monitoring is conducted and reported. … So the conclusions have to be pessimistic if all the studies you have to review focus on monitoring species with the highest risk of extinction.
I haven’t read the paper, but did listen to a More or Less episode about the paper. The episode discusses the poor quality of the available data and left me feeling similarly. The radio episode also highlights a potential bias in search strategy used by the authors in their meta-analysis that would favor finding an overall population decline. If I recall correctly, it was something along the lines of the authors searching with keywords related to “declining populations”, so they would naturally tend to be including papers that found declines and excluding papers that found population increases. This idea squares with your interpretation that the −2.5% number shouldn’t be interpreted as a projection for total insect biomass or numbers.
Good point. I was commenting more on my perception of the conservation field rather than considering biases in the methodology of this study, but they keywords used were:
[insect*] AND [declin*] AND [survey]
Which does is completely biased to finding studies showing insect declines. Fig 1. also shows that most of the included studies were done in the US and Europe, with very little data coming from the tropics where most insect diversity is.
I haven’t read the paper, but did listen to a More or Less episode about the paper. The episode discusses the poor quality of the available data and left me feeling similarly. The radio episode also highlights a potential bias in search strategy used by the authors in their meta-analysis that would favor finding an overall population decline. If I recall correctly, it was something along the lines of the authors searching with keywords related to “declining populations”, so they would naturally tend to be including papers that found declines and excluding papers that found population increases. This idea squares with your interpretation that the −2.5% number shouldn’t be interpreted as a projection for total insect biomass or numbers.
Good point. I was commenting more on my perception of the conservation field rather than considering biases in the methodology of this study, but they keywords used were:
Which does is completely biased to finding studies showing insect declines. Fig 1. also shows that most of the included studies were done in the US and Europe, with very little data coming from the tropics where most insect diversity is.