[thaumasiotes]

> This study found that the allochthonous input (land to water) coming from the crickets jumping into a Japenese stream was a large part of an endangered trout species' diet. In short, his trout was kept alive because of a parasite driving crickets to drown themselves.

The summary doesn't seem to follow from the finding. The fact that you mostly just eat crickets that walk up and ask to be eaten doesn't immediately imply that, if the crickets stopped doing that, you'd starve to death. It should be easy to understand the choice to go with a low-effort option even if there's also a higher-effort option available.

[mc_maurer]

There's an inherent cost to foraging, so a high-quality food item that requires little effort is a much greater net energy benefit. When we're talking about an endangered species whose margins are quite slim to begin with, this can be a big difference maker. A couple dead trout reduces the population size, increases inbreeding depression, things aren't looking so good. I certainly oversimplified the mechanisms here, but a change in 60% of an organism's diet is not easily dismissed.