Who!, Who!, Who Did I Eat? Part I
Purpose: To learn about owl and rodent behavior.
Pre-Lab Information: Owls, along with hawks and eagles, are part of a group of birds called raptors, or
birds of prey. These are birds that actively hunt other animals for food and catch their prey with claws
called talons. Owls are members of the kingdom Animalia, the phylum Chordata, the class Aves, and the
order Strigiiformes. Barn owls are in the family Tytonidae, with the Genus and species of Tyto alba.
There are twenty- four species of owls, eighteen of which live in the U.S. Barn owls are a common
species of owl found throughout the world, except in the coldest and extreme hottest climates. Barn owls
live in areas of open fields, pastures and scrublands. Barn owls nest in hollow trees in the wild, but prefer
old barns and silos, hence the name. Nests are made of regurgitated pellets. As Many as thirteen eggs can
be laid at one time. The eggs hatch in approximately a month. The young owls are fed in the nest for six
to ten weeks, before they are mature enough to hunt on their own. Most barn owls die in the first two
years, but can live up to eight years. Parents usually nest three times in a year.
Owls are superbly adapted to their environment. They can fly noiselessly through the night and
swoop down on unsuspecting prey with pinpoint accuracy. Owl’s ears are located in a feathery depression
behind their eyes. This depression funnels in the sound waves, allowing them to hear even tiny footsteps
on the forest floor. They also have very sharp eyesight. The front of an owl’s wing has hair-like feathers,
which prevent the air from making any sound as it flows over their wings in flight. Owls therefore, can
attack their prey without making any noise. Large talons on their feet catch and hold prey, while their
beaks are used to crush the prey’s head or break its neck.
Owls eat mice, tiny mouse-like rodents called voles and shrews, small birds, and rats. They have
no teeth and do not rip their prey to smaller pieces like hawks and eagles do. Instead, owls swallow their
prey whole. The animal is digested with the help of enzymes in the owl’s stomach. However, bones and
fur are not digested. A muscle in the stomach prevents the bones from passing on to the intestines along
with the protein, fat, and carbohydrates necessary for life; the owl must regurgitate the bones. To prevent
them from getting stuck in the throat, the fur is pressed around the bones by muscles in the stomach. The
bones and fur then form a pellet that can be regurgitated without harming the owl. These pellets can be
found on the forest floor near where barn owls live. By examining these “pellets” we can determine what
types of animals, and in what amounts, the owls are eating.
Owls eat a variety of small rodents including: mice, rats, voles, and shrews. Voles are the most
common rodent eaten by owls. They are small rodents that measure 4 to 8.5 inches long and weigh 0.8 to
3 ounces and vary in color from brown to gray. They are pudgy, with blunt faces and small eyes, small
ears, short legs, and a short tail. Eight species of voles are distributed widely throughout Colorado. They
often are found in heavy ground cover of grasses, and grass-like plants. They are found in moist and welldeveloped forests, or near damp marshy areas or wet meadows. Voles eat a variety of grasses and crops.
They also eat bark on trees and shrubs. Voles are active day and night throughout the year. They usually
live between 2 and 16 months. Voles construct underground tunnels with numerous entrances. 14 to 500
voles per acre are common. Voles have three to six young per litter and three to 12 litters per year. Mice
are similar in size to voles, but have more pointed faces, thinner bodies, and longer tails. Shrews look
much like mice and voles, but are smaller and have more pointed heads, even than mice.
Data: Make a table in which you can list owl characteristics that would be helpful to the owl in hunting
its prey. In a similar table, list vole characteristics that might be helpful in preventing it from being eaten.
Analysis: Discuss, in one well-written paragraph, the relationship between small rodents and owls and
how each has adapted to its environment.