Among the following birds, choose the one which is least like the others in the group.

Introduction / Context:
This general knowledge and classification question deals with common birds. Although all the options are birds, one of them belongs to a different ecological or behavioural category compared to the others. The task is to pick the bird which is least like the others.

Given Data / Assumptions:

• Sparrow, a small seed eating bird often found in human surroundings.
• Parrot, a colourful bird, often herbivorous and sometimes kept as a pet.
• Swan, a large graceful water bird, mainly herbivorous, living around lakes and rivers.
• Vulture, a large bird of prey that feeds mostly on carrion (dead animals).
• Pigeon, a medium sized bird that eats grains and is common in cities.
• We assume basic knowledge of diet and behaviour of these birds.

Concept / Approach:
A natural way to classify birds is by their feeding habits and their roles in the ecosystem. Sparrows, parrots, swans and pigeons are generally not scavenging birds of prey. They mainly feed on seeds, grains, fruits or aquatic vegetation. Vultures, in contrast, are scavengers and birds of prey that primarily feed on dead animals. This ecological difference makes vultures stand out in the group.

Step-by-Step Solution:
Step 1: Sparrow is a small bird that usually eats seeds and small insects. It is not a predatory or scavenging bird of prey.Step 2: Parrot is generally herbivorous or omnivorous, feeding on fruits, seeds and nuts. It is not known as a bird of prey.Step 3: Swan feeds mainly on aquatic plants and small organisms in water bodies. It is not a scavenger; it is considered a waterfowl species.Step 4: Pigeon usually eats grains, seeds and food scraps. It may scavenge food in cities, but it is not a raptor or specialised scavenger.Step 5: Vulture, however, is a scavenging bird of prey. It feeds primarily on carrion and plays an important role in cleaning up carcasses in the environment.Step 6: Therefore, four of the birds (sparrow, parrot, swan, pigeon) are mostly seed eating or plant eating and are not classified as birds of prey, while vulture is a true scavenging raptor.Step 7: Because of its unique ecological role as a scavenger and bird of prey, vulture is least like the others.

Verification / Alternative check:
Another perspective is to look at beak shape and general appearance. Sparrows, parrots, swans and pigeons have beaks suited for pecking seeds, fruits or plants, whereas vultures have hooked beaks adapted for tearing flesh. This morphological difference reflects their different diets and further confirms that vultures belong to a different category.

Why Other Options Are Wrong:
Sparrow, parrot, swan and pigeon all belong to non raptorial bird groups and are mainly herbivorous or grain eating. They do not specialise in feeding on dead animals. Because they share similar non predatory feeding habits, they naturally form a group. None of them has the distinct scavenger role that vultures have in the ecosystem.

Common Pitfalls:
Some students might think that swan is different because it is a water bird, while the others are more land based. However, classification questions usually focus on more fundamental ecological roles rather than habitat alone. The clear distinction in diet and predatory behaviour between vulture and the other birds is a stronger and more standard exam pattern.

Final Answer:
The bird which is least like the others in the group is Vulture.