Dung is much easier to digest because its already been digested by another animal

Nutrient content is much richer in detritus

There is less competition for detritus than other resources

There are no special adaptations required to be a detritivore

There is more detritus than live biomass

Herbivores are limited by their predators

Herbivores generally only eat one plant

Most herbivores are very small

Herbivore population sizes are controlled by the climate

Herbivores are not diverse enough nor do they have enough adaptations to eat all plants

All of these

All the available food cannot be eaten

Not all ingested food can be absorbed into the body

Not everything absorbed into the body is used for growth

The conversion of food into biomass results in heat loss

A western diamondback rattlesnake that preys on field mice that eat seeds and berries

A black-tailed deer that browses on grasses and shrubs

People who are keen to eat bear, which eats small mammals that live off berries and seeds

A maple tree that stores energy harnessed from the sun in the form of sugars through a process called photosynthesis

Earthworms, bacteria and fungi that decompose plant matter on the forest floor to replenish the soil