The following adaptations are associated with the flight of birds except

Analyze the question: We need the one feature that is NOT an adaptation for flight in birds.

Concept: Birds are adapted for flight in these main ways:

• Light body: hollow (pneumatic) bones, no teeth, and no urinary bladder reduce weight.
• Streamlined body: reduces air resistance as the bird moves through the air.
• Powerful flight muscles: the pectoral muscles move the wings, and they attach to the large keel (breastbone).
• Feathers and wings: the forelimbs are modified into wings that give lift and thrust.

Evaluate each option:

• A. Reduced body weight: This is a flight adaptation, because a lighter bird takes off and stays airborne more easily.
• B. Streamlined shape: This is a flight adaptation, because it lowers drag.
• C. Powerful muscles: This is a flight adaptation, because strong pectoral muscles drive the wing beats.
• D. Clawed digits: This is not directly a flight adaptation. Claws are used for perching, grasping prey, scratching the ground or walking, not for flying. The forelimb digits are fused or reduced in the wing to support the feathers.

Answer: D.

Exam tip: In "except" questions, the three correct-sounding options are usually the ones that relate to lightness, streamlining and strength. Pick the option about something else, such as feet, claws or diet.