Owl Pellet Dissection Lab Thursday 12/10/15

Names: ______

Owls are predators. Most larger owls feed on small mammals, birds and reptiles. Owls usually swallow their food whole or in large chunks. The owl’s digestive system cannot digest fur/hair, bones, teeth, feathers, etc. Rather, a portion of the owl’s stomach compresses these parts to form the pellet. The pellet does not pass into the intestine of the owl; instead, the owl regurgitates (coughs up and spits out) the pellet. In an owl pellet, in addition to bones, you may find the exoskeletons of insects, feathers, fur/hair, fish scales, small white grubs and various types of seeds. By examining what is found in the pellet, you, as well as scientists, can tell what and how much an owl has eaten.

  1. When scientists dissect an owl pellet, the mass may be taken. Do you think there would be a connection between the mass and the number of skulls found in our pellets? What about the size of the pellet at the number of skulls found?
  1. Owl pellets are uniformly dark gray, from 1 inch to 3 inches long and 3/4 to 1 inch in diameter. These pellets can be found where owls roost, usually in open barns or in big trees which offer protection from bright light. They are odorless, but may be "whitewashed" by the owl since they fall beneath the perch. Describe the owl pellets you used. Did they match this description? If not, what were the differences?
  1. List at least three things that scientists can learn from dissecting owl pellets.
  1. Did you find any insects or insect parts in the owl pellet? Would you expect to find any? Why?
  1. Owls, hawks and eagles are types of Raptors. Raptors are birds with hooked beaks and sharp claws, and are therefore adapted for seizing prey animals. Hawks and eagles differ from owls in that they eat their prey animals by tearing them into small pieces, picking out the flesh and avoiding most of the fur and bones. They also have strong stomachs which can digest most of the bone material which they might eat. The relatively small amount of indigestible bone and fur that remain will be compacted by their stomach muscles into a pellet similar to the owl's. Do you think you would learn as much from dissecting hawk and eagle pellets? Why?
  1. Illustrate your own food web from the animals and plants that may be involved.