Fig. 301.—An Altrical Bird, i.e. poorly developed at hatching. Young pigeon, naked, beak too weak for eating.
Draw an outline of the bird seen from the side. Make drawings of the head and the feet more detailed and on a larger scale.
Fig. 302.—A Precocial Bird (well developed at hatching). Feathered, able to run and to pick up food. Precocity is a sign of instinctive life and low intelligence. A baby is not precocious.
Question: Is pigeon or fowl exposed to more dangers in infancy?
Why does a goose have more feathers suitable for making pillows than has a fowl? In what country did the domestic fowl originate? (Encyclopædia.) Why does a cock crow for dawn? (Consider animal life in jungle.)
Activities of a Bird.—Observe a bird eating. Does it seem to chew or break its food before swallowing? Does it have to lift its head in order to swallow food? To swallow drink? Why is there a difference? After feeding the bird, can you feel the food in the crop, or enlargement of the gullet at the base of the neck? (Fig. [304].)
Feel and look for any movements in breathing. Can you find how often it breathes per minute? Place hand under the bird’s wing. What do you think of its temperature; or better, what temperature is shown by a thermometer held under its wing? Do you see any connection between the breathing rate and the temperature? Test (as with the crayfish) whether a bird can see behind its head. Notice the movements of the nictitating membrane. Does it appear to be transparent?
Watch a bird fly around a closed room and review the questions on Control of Flight.
Bend a bird’s leg and see if it has any effect upon its toes. Notice a bird (especially a large fowl) walk, to see if it bends its toes as the foot is lifted. Pull the rear tendon in a foot cut from a fowl for the kitchen. Does the bird have to use muscular exertion to grasp a stick upon which it sits? Why, or why not? When is this bending of the toes by bending the legs of special advantage to a hawk? To a duck? To a wading bird? Why is a fowl safe from a hawk if it stands close to a tree?
