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Owl Pellets Provide a Lesson in Animal Digestion

What happens when you eat? You feel full and get lots of energy. But you can’t absorb every part of your food into your body. There is waste. Eventually you must visit the toilet. It’s natural! 


An own in a tree regurgitating an owl pellet.
A northern saw-whet owl regurgitating an owl pellet. (Photo via Shutterstock)

Your lunch just followed your digestive system. A digestive system is the parts of our body that breaks down food to give us fuel and energy. That’s how we get the nutrients we need to live. Your mouth? That’s a part of it. Your stomach? You got it! Every animal has one, and they are not all the same!


What if you said “no thanks” to forks and knives and stuffed an entire chicken wing into your mouth? You swallow all the bones, even the feathers, along with the meat. Yum? Well not for humans, because our digestive system is not set up for that style of eating.


Some animals have a different digestive set up. They can swallow bones, teeth, feathers, fur and claws. How does that work? Let’s look at the most popular example: owls.


 

Words to know

Absorb: To take in something in a natural or gradual way.

Gizzard: A muscular, thick-walled part of a bird’s stomach for grinding food.

Regurgitate: To bring up to the mouth again.

 

Owls hunt their prey, say a mouse. They swallow their food whole, or maybe tear it into a couple of chunks. The muscles and other meaty bits pass through their two-part stomach. All that nutritional goodness makes its way down the rest of the digestive track, just like yours. Some is absorbed as fuel. Some is pooped out as waste. 


The stuff it can’t digest, like the bones and fur, are smushed together in the gizzard for several hours. Now owls have this hard, compressed pellet in their gizzard. What do they do with it? What would you do with a pellet? They regurgitate it up. Scientists call this process casting. No, it’s not vomit. Think of it more as a hairball that a cat coughs up. 


What do pellets look like? 


Their shades range from black to gray to brown to tan. Barn owls’ pellets usually start out black but fade with time. You can figure out a pellet’s relative age by the color. Which barn owl pellet looks newer in the picture below? 


Barn owl pellets. (Photo via Shutterstock)

Pellets are rounded and usually oval. Although hard, the surface might feel like felt fabric thanks to the compacted fur. Do you have a felt hat or scarf at home? Or have you made an art project out of felt? Imagine that texture. A few bones or teeth might peak out. 


Who casts pellets? 


All owls cast pellets. But other birds who hunt animals make pellets, too! We are talking hawks, falcons, eagles, herons, cormorants, grebes, kingfishers, swallows and many shorebirds. 


Why do we usually only hear about owl pellets?


These are the pellets that you dissect in science class. Owl pellets are usually larger, and they usually contain more complete bones compared to other pellet-casting birds. This is because owls eat their prey whole. Plus their stomach acid is not as strong as other birds, so it doesn’t dissolve the bones as much. 


What’s in a pellet?


Check out all the fur and bones in this owl pellet. How many bones do you see? (Photo via Shutterstock)

All the bones, teeth, fur, feathers and claws of whatever animal they ate. You might even find the exoskeletons of insects or accidentally swallowed plant materials. There might be up to five animals in one owl pellet!


Have you ever found a pellet outside? 


How wonderful! It’s amazing to poke at a pellet you find outside to see the bird’s delicious menu. But you should not handle one you find on the ground. Bacteria and viruses hang out in them. Instead, dissect professionally sanitized pellets. You can find places to buy them online. 


Pellets are an incredible part of some birds’ digestive systems. Keep a watch for any birds out there that might be casting a pellet. What other ways do different animals deal with digestion? Think about that next time you eat dinner!

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