When I said that humans damage the environment, I was mostly referring to things like deforestation, destruction of habitat, hunting species to extinction, air/water pollution, light pollution (trees get confused by night time illumination), and anything else that we do which disrupts the ecosystem.
When a bird eats an insect by the way, it's not damaging anything. It's playing its role in the ecosystem by helping to control the population of insects. Same idea with any other predator. In nature there's a balance to everything. When humans eat animals these days, 99% of the time that animal was bred and raised for that sole purpose. If humans actually went out to personally hunt and kill every animal that they ate (particularly those animals that need population control due to human caused lack of natural predators), I would have no problem with it in terms of ethics. Though, if people had to do this every time they wanted to eat some meat they might settle for alternatives.
