Life Cycle - Natural Environment (2B)
Pre Lab 

   
OBJECTIVES:
  • Investigating the life of owls.
  • Comparing environments of different owls.  
VOCABULARY:
  • nocturnal
  • predatory
  • raptor
MATERIALS:

Students use a worksheet to compare different owls.

 Screech Owl

BACKGROUND:

The word "owl" is the common name for nocturnal birds of prey (raptors).  Owls are sometimes associated with the occult and the strange.  They became symbolic of intelligence because it was thought they predicted events.  The barn owl in Europe was looked upon as a bird of ill omens and a symbol of darkness.  

Owls unlike other birds of prey, have virtually noiseless flight.  They range in size from 8 centimeters (five inches) (North American elf owl) to 84 centimeters (33 inches) (Great Gray Owl).   On each side of the beak there are several rows of small curved, stiff-shafted feathers, which form a ruff to support the features around their eyes.  Some species have horn-like tufts near their ears.  

Owls have very large eyes which maximize light gathering in conditions of minimum light, thereby enabling them to see at night.  The orbs of their eyes are directed forward, giving owls binocular vision.  They are able to see their prey in a three-dimensional manner. However, an owl's eye cannot rotate, so owls have to move their entire head to continue looking at an object that is moving.

A few tropical African and Asian owls are fish eaters but the majority of owls feed on small mammals and birds which they kill with their feet.  They usually tear the larger prey to pieces,  then swallow the parts,  including  fur, feathers and bones.   Smaller prey is often gulped down completely.  About 12 hours after eating the prey is digested; the bones, fur, and feathers are coughed up in small pellets. Examination of these owl pellets has produced knowledge as to the feeding habits of the different species of owls.  These studies have shown that owls are very beneficial to the agriculture of their area, for while they consume large numbers of rodents they destroy few beneficial insects or birds.  

PROCEDURE:

  1. Students will explore the food chain of an owl  lab. Different species of owls have different food chains.  The worksheet has students looking at Pel's Fishing Owls, Elf Owls, Spectacle Owls, and Scops Owls.  Instruct students to color them after you have gone over the information given below. 
      
  2. You are given information to discuss with students below.  See if they can interpret what type of prey each owl eats after you discuss each of the owls. You may want students to start learning how to take "notes" on each of the birds so they can remember the information later. 

PEL'S FISHING OWL (Scotopelia peli)

A huge impressive owl, considered on of the largest owls in the world.  Fishing owls are found in Asia and Africa.  Like other owls, the Asian owls have ear-like tufts of feathers on their heads, but the African fishing owls do not.  All fishing owls have extra long powerful toes armed with strong claws, the undersides of their toes have pointed, spiky scales.  As they catch fish by flying low over the water and seizing the prey with their feet, these scales give even a slippery fish little chance of escape.   The Pel's fishing owl is the most common African fishing owl, and lives near wide rivers.  It hunts at night, when its huge-fronted eyes let in light and they are able to see clearly even by starlight.  They have loud, resonant calls which consist of either repeated short hoots, or a much longer, deep booming call.  By day, they usually roost in the trees.  In the early evening, they often sit on rocky crags, watching the river below for fish. 

ELF OWL (Micrathene whitneyi)

The Elf owl is also called Whitney's owl after its discoverer. It has yellow eyes and is buff colored with dark streaks.  Their egg are white.  It has a round head with no ear tuft, a chunky body and short tail.  It is one of the smallest owls in the world  raining in size from 8-10 cm) and weighs only 1.5 ounces. This particular species of owl is found only in the dry parts of the southwest United States and in Mexico, where it is also known as the cactus owl.  Elf owls frequently make their nests in the trunks of candelabra cactus trees.

The elf owl is more thoroughly nocturnal than most other species of small owls, usually spending the entire day in hiding.  It is primarily an insect-feeder, consisting largely on night flying moths and locusts, skillfully caught while the insects are on its wing.  It also catches the odd lizard.  Its hooting is very loud for a bird of its size and can be heard a long way off. 

SPECTACLED OWL  (Pulsatrix perspicillata)

Spectacled owls live in the densely warm, damp tropical rain forests of South America.  Here the trees have long trunks devoid of leaves, and all the leaves are at the top of the tree, forming a thick green canopy which stops the sunlight from reaching the forest floor.

This owl feeds on small mammals, such as baby squirrel monkeys, marmosets, squirrels, and mice and on insects such as dragonflies, butterflies, and moths.  Although most owls are nocturnal, the Spectacled owl will hunt in the dim light under the canopy during the day. 

SCOPS OWL (Otus scops)

A Scops owl or Screech owl is rather a mysterious bird that has a long slim body and speckled plumage which can trick the observer into thinking it is just a withered tree stump.  This small owl is migratory.  These owls live throughout the world, but this variety is from the Mediterranean.  This species likes orchards  especially  olive groves.  In mountain areas it occurs up to 4,000 feet but not beyond because it is too chilly.  The monotonous song, a series of hoots emitted at brief intervals, is performed by the male.

Like most owls, the Scops rest during the day and starts hunting at dusk.  It is primarily a hunter of insects, especially big insects such as hawk moths, and streaks through the air in pursuit of them.  It is sometimes seen perched near street lighting, waiting for insects.  It supplements this diet with rodents and small birds.

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