Question

Consider the following food chains:

(a) Plants → Mice → Snakes → Hawks 

(b) Plants → Mice → Hawks 

If energy available at the producer level in both the food chains is 100 J, in which case will hawks get more energy as food and by what factor? Justify your answer.

Answer 1

In case of b hawks will get more energy as they are placed in third trophic level in food chain b but in food chain a, they are placed at fourth trophic level. According to 10% Law by Lindeman only 10% of energy is transferred from one trophic level to next. So organisms placed at higher trophic levels will get less energy than organisms placed at lower trophic levels.

If energy available at the producer level in both the food chains is 100 J than in first case according to 10% law mice will get 10 J which is 10% of 100 J, snakes will get 1 J and Hawks will get 0.1 J. In second case mice will get 10 J and hawks will get 1 J according to 10% law. So in first case hawks will get 0.1 J and in second case hawks will get 1 J of energy as food.