Classification – Identify the odd one out among the following birds by focusing on ecological role and feeding behavior. Three belong to the same natural class, while one differs in a key biological trait. Which option does not belong to the group? Options: Parrot, Koel, Vulture, Swan.

Introduction / Context:
Classification (odd-one-out) questions test your ability to recognize a unifying rule across most items and to detect the single exception. Here, all four names are birds, so the surface category is the same; the task is to probe deeper biological or ecological traits such as diet, behavior, or typical role in the ecosystem.

Given Data / Assumptions:

• Parrot: primarily herbivorous/omnivorous, non-raptorial.
• Koel: a cuckoo, omnivorous/frugivorous, songbird, non-raptorial.
• Vulture: a raptor specialized as a scavenger.
• Swan: a waterfowl, mostly herbivorous/omnivorous, non-raptorial.

Concept / Approach:
Look for a shared functional category among three items (non-raptorial birds) and a contrasting category for one item (raptorial scavenger). The odd-one-out will violate the dominant grouping rule inferred from the majority.

Step-by-Step Solution:
Step 1: Note that Parrot, Koel, and Swan are generally non-raptorial birds.Step 2: Identify Vulture as a raptor with specialized scavenging habits and anatomical adaptations for tearing flesh.Step 3: Since three share a non-raptorial profile and one is raptorial, the exception is Vulture.

Verification / Alternative check:
Check diet and beak/talons morphology: vultures have hooked beaks and strong talons typical of birds of prey, unlike the other three, confirming the classification choice.

Why Other Options Are Wrong:
Parrot: Non-raptorial; fits the majority group.
Koel: Non-raptorial; fits the majority group.
Swan: Non-raptorial waterfowl; fits the majority group.

Common Pitfalls:
Avoid superficial cues (habitat or color). The decisive trait here is ecological role (raptor vs non-raptor).

Final Answer:
Vulture