Hawks, falcons, eagles, herons, egrets, crows, and many other birds have this adaptation as well! Can you guess what it is? Here's a hint: think eating. Did you answer that all of these birds poop? You would be correct, but they also create pellets. I know what you are thinking, "Mrs. Morissette, did you say pellet?" That's right! All of these birds regurgitate anything they can't digest into a compact pellet. Pellets may contain fur, bones, claws, teeth, exoskeletons, and even bills if the bird consumed another bird.
Don't feel the least bit concerned if you didn't know that these birds cough up pellets. It was only recently, that I discovered that owls weren't the only birds that did this. To understand a little more about why these pellets are created, let's talk bird digestion.
Birds have a very intricate digestive system. Birds lack teeth, and therefore, they have a special stomach. Their stomach contains two parts. Scientifically these parts are known as the proventriculus and the ventriculus. The proventriculus is a glandular stomach that uses acids, enzymes, and mucous to start digestion. The ventriculus is also called a gizzard. Gizzards are muscular stomachs used to grind up a bird's food. Some birds consume grit to assist the gizzard with grinding. The gizzard uses muscle contractions and grit to break the bird's food into smaller pieces, much like your teeth do for you! After the gizzard grinds the food, the digestible pieces will travel to the small intestine. The gizzard will form the indigestible pieces into a pellet. Pellets will then move back to the proventriculus where they will stay for up to 10 hours. Birds will then regurgitate the pellet. If you would like to take a closer look at an owl's digestive system, click on the link below.
There are two main differences between the digestive system of owls and that of other raptors. Owls lack what is known as a crop. A crop is an enlarged part of the esophagus that allows birds to store food. Since owls lack a crop their entire meal passes directly to the proventriculus. Owls also tend to eat their prey whole since they have no place to store extra food. The second difference is that owls have weaker stomach acids, and therefore, items that dissolve in the stomachs of other raptors are regurgitated in an owl's pellet. Hawks and falcons regurgitate smaller pellets containing mostly hair, whereas owl pellets are larger and contain more bones.
Check out the videos below to see an owl pellet and owl pellet dissection. I also encourage you to get out and find some pellets of your own. If you break one open, use a stick. Don't touch the pellet with your bare hands. They can contain bacteria that can make you sick.
On a separate note, I took a picture of an animal's tracks in the snow, can you identify what animal left them? If you can, email me at email@example.com, and the next time I am in your class, I will bring you a little prize!!
Happy Exploring Watershed Explorers! I hope that you will bundle up and enjoy the snow tomorrow.