Owl Pellet Lab Conclusion

2/26/16

Owl Pellet Lab Conclusion

Our group taking apart our owl pellet- photo from Mr. Orre

The wonderful amount of fur that came from our pellet.

  In this lab we dissected owl pellets. First, we read an interesting packet about how owl pellets were formed, as they are just regurgitated by owls after they eat their prey. Then we picked our foiled wrapped pellet and started to pull apart the fur to separate out the bones. Unfortunately for us, our pellet was very densely packed so it took a lot of careful, slow fur pulling to loosen some of the bones. After we picked out all the bones, we set to work on trying to identify what animal the prey was based off of the skeletal structure by comparing what we had to pictures in the packets.

Hip joint of a rodent- photo by Mr. Orre

 After dissecting our owl pellet, my lab partner and I decided that the owl which the pellet had come from most likely ate some type of rodent and multiple of them. The bones we collected from the pile of compacted fur were all pretty intact. They consisted of various length long bones and a lot of irregular bones, which ended up to be probably almost a full collection of vertebrae. The long bones looked to be femurs and ribs. Unfortunately, we did not obtain a skull from the pellet, as the one to one ratio is not always perfect. Without a skull it was hard to determine what animal the owl actually ate, therefore, a rodent was the best guess we could make. Of course, even without the skull there were a few hints that told us what the owl had eaten. First was the femur bones that connected with the hip sockets that we found. Since both the femur and the hip bone were intact, we were able to assume that the unique hip bone structure was that of a rodent. The vertebrae too resemble a structure close to a human's, which also lead us to believe that the prey was a rodent.

The bones we found in our owl pellet, which lead us to believe that we found a rodent and multiple of them.

  One difference between a rodent skeleton and that of a human is the hip bones (the long bones with a loop on them). A close up of the pelvis and femur and the hip joint is included above at the very top. It was very apparent in the lab as the rodent's hip bone are much longer since they walk on all fours while we humans must maintain balance on two. Another difference is that the tibia and the fibula are switched in rodents, whereas in humans the tibia is the bigger bone compared to the fibula. Thirdly, rodents and human both have vertebrae, but rodents only possess 24 while human have 33 (the vertebrae are the weird roundish looking bones in the picture above). However, this was also a similarity as well because the way the vertebral column was structured was similar to humans. Our vertebrae grow larger the farther down the column we go and the same applies for the rodents. Another similarity was that rodents and humans both have 24 ribs to protect their organs from harm. In the picture above, the tiny scattered long bones are ribs. Lastly, the skull of rodents varies immensely from that of a human due to a difference in function. However, without a skull our group found it hard to identify this difference. Below is a picture of a rodent skull from some of our friends instead.

Skull from our friends since we didn't find one