Net energy is the amount of that is actually useable from an energy resource. Net-energy ratio is the ratio of the amount of useable energy from a resource and the amount it takes to make that energy useful. ... An energy source with high energy efficiency provides a lot of work for the amount of energy used.
Herons are very large birds, and due to their intimidating size, they have very little predators. They have a varied diet and consume many different prey (fish, snakes, amphibians, and probably many other small animals). If the population of herons would decrease, the population of the other organisms living in the same environment would increase since they would have a greater chance at survival (since they are not being eaten by the herons)
I think the answer would be needs. Hope this helps.
