Animals: Birds

To help the bird swim by pushing water backwards

Step 1: Webbed feet have toes joined together by a layer of skin, like a paddle. Step 2: When a duck moves its webbed feet in water, it pushes the water backwards. Step 3: This backward push of water moves the duck forward — just like how paddles work in a boat. Step 4: Climbing trees is done by climbing birds like parrots. Scratching ground is done by hens with hard claws. Holding prey is done by eagles with talons. Step 5: So the main purpose of webbed feet is to help the bird swim.

Sparrow

Step 1: Perching birds are birds that sit or rest on high branches without falling, even while sleeping. Step 2: Perching birds like crow, sparrow, and mynah have three toes pointing forward and one at the back. Step 3: This special toe arrangement helps them grip branches firmly. Step 4: Eagle is a preying bird with talons. Duck is a swimming bird with webbed feet. Heron is a wading bird with long, slender legs. Step 5: Among the options, sparrow is the perching bird.

It makes their body lighter so they can fly more easily

Step 1: Flying requires a lot of energy, and a heavy body makes flying very difficult. Step 2: Birds have hollow bones — this means the inside of their bones is mostly empty, not solid. Step 3: Hollow bones are much lighter than solid bones, which reduces the overall weight of the bird's body. Step 4: A lighter body means the bird needs less energy to lift itself up and fly. Step 5: This is one of the key adaptations that allows most birds to fly. Heavy bones would make flight impossible.

Downstroke movement

Step 1: Birds flap their wings to fly. This flapping has two parts. Step 2: When wings move UPWARD and BACKWARD, it is called the UPSTROKE movement. Step 3: When wings move DOWNWARD and FORWARD, it is called the DOWNSTROKE movement. Step 4: Migration means birds travelling long distances to warmer places — that is a different concept. Perching means sitting on a branch. Step 5: So, the correct answer is downstroke movement.