If an organism takes in 1,000 kilojoules of energy in the form of food, how much of this energy still exists after the organism has used the energy to build new cells, repair damaged cells, pump its heart, and run from a predator?

Through different studies scientist have quantified the amount of energy that moves to the next trophic level. Most of the energy is used for metabolic processes and released as heat to the environment.

The amount of energy left for the next level is around 10%, if a herbivore takes 1,OOO Kilojoules the energy left for the next level would be around 100 Kilojoules, this explains why you cannot find a food chain with more than 7-8 levels (ocean) on land is usually between 4-6 levels.

Birds, unlike mammals, do not have separate exits for urine and feces. Both waste products are eliminated simultaneously through the cloaca. While mammals excrete nitrogenous wastes mostly in the form of urea, birds convert it to uric acid or guanine, which reduces water loss in comparison.