Answer:
The size is reduced as 80-95% of the available energy at one trophic level is not transferred to the next
Explanation:
There is loss of energy as it is transferred between trophic levels. The decrease in energy as it moves up the pyramid is due to energy loss as metabolic heat when one organism is consumed by another from the next level as it moves up the trophic levels.
Protection of certain species is a very controversial topic. Many species like the mountain lion or jaguar that are near extinction in certain areas, are threats to human life. Another reason is that they could off set the food chain when they come back and be stonger than ever. For example the mountian lion could eat out the thriving white tail deer population which was struggling because of the mountain lion. And many people rely on white tail deer for food.
Hope this helped :)