_____ हा एक निसर्गाच्या साखळीतून अस्तंगत झालेला पक्षी आहे.

The correct answer is Option B (Dodo).

Key Points:
• Extinct Avian Species:
• The Dodo (*Raphus cucullatus*) was a flightless bird endemic exclusively to the island of Mauritius.
• Following human arrival and the introduction of invasive predators (pigs, dogs, rats), the species suffered complete habitat destruction and hunting pressure, culminating in total global extinction by the late 17th century (around 1662–1681).
• Conservation Status of Other Options:
• Vultures (गिधाड): Critically Endangered due to toxic bioaccumulation of the veterinary anti-inflammatory drug *Diclofenac*, but not biologically extinct.
• Sparrows (चिमणी): Suffered urban population declines, currently listed as Least Concern globally.
• Therefore, the bird that has completely vanished (extinct) from the natural ecosystem is the Dodo (Option 2).
• Key Takeaway: The Dodo of Mauritius is a classic historical example of an avian species completely extinct from global ecosystems.