Food Webs -Energy Pyramid -Diet of an Owl

Monday, April 22, 2019


The object wrapped up in this aluminum foil can help us understand food webs.

owl pellet


Owls like most birds cannot chew their food Owls swallow their prey whole.

What happens to the indigestible material like bones and skulls? This material is compressed in the gizzard and looks like a little pellet. This compressed owl pellet is then expelled by the owl.

Many times in Science classes you may dissect this pellet to see what the diet of the owl consists of. You will find the bones of the animals the owl consumed which tells you how an owl receives energy

A food web is a diagram that shows the transfer of energy in an ecosystem.    


An ecosystem is a community of living organisms and the interactions between the biotic and abiotic factors. The biotic factors are the living components like the owl, and abiotic factors are non-living like the air and water.

Let’s create a food web of an owl to help us understand this diagram

Here is an owl in its ecosystem. It is missing the arrows so let's start adding the arrows

First, an owl eats rodents like rats and shrews and occasionally small birds. 

So let's add some arrows. The arrows point in the direction of the transfer of energy. The energy of the rodents is transferred to the owls so the arrows are pointed in that direction. The bird's energy is transferred to the owl so the arrows point towards the owl. The owl is considered the tertiary consumer because it is the topmost level and feeds on other carnivores


Next, what do the rodents eat?

Rodents eat a variety of insects like grasshoppers, pause along with worms, pause, and small snails, pause So the energy of these animals is transferred to the rodents so the arrows point towards the rodents.

Birds eat a large variety of organisms including worms, fruit, amphibians, and even snails

The bird and rodents are secondary consumers because they consume primary consumers.


Grasshoppers and snails eat producers like carrots, leaves, and other producers. They are considered primary consumers because they consume mainly producers.

The plants are producers because they use sunlight to produce their energy


As you move from one trophic level to the next, like from the plants to the grasshopper only 10 percent of this energy is transferred

This is one reason you always have a small number of birds of prey in a particular area. It takes a large area to support an owl.

So a food web is a model that shows a transfer of energy in an ecosystem.


In addition, there are decomposers like bacteria and fungi that are breaking down once-living organisms which recycle materials

The plants which are your producers absorb these recycled nutrients and this way the nutrients are returned to the ecosystem.


MooMooMath and Science


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