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International Journal of Zoology and Applied Biosciences Research Article
Evolutionary adaptations for obligate diving in the flightless cormorant (Phalacrocorax harrisi)
Priyadharshini P, Aswini L, Swathi T, Monish Raj R and Pradeepa A K
Year : 2025 | Pages: 68-72
Received on: 15/09/2025
Revised on: 20/10/2025
Accepted on: 31/10/2025
Published on: 12/11/2025
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Priyadharshini P, Aswini L, Swathi T, Monish Raj R and Pradeepa A K( 2025).
Evolutionary adaptations for obligate diving in the flightless cormorant (Phalacrocorax harrisi)
. International Journal of Zoology and Applied Biosciences, 10( 6), 68-72.
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Abstract
The Phalacrocoracidae (cormorants) present a unique evolutionary challenge, navigating the fundamental physical constraints imposed by the buoyancy-inertia trade-off necessary for efficient pursuit diving while maintaining the physiological capacity for flight. The Galapagos Flightless Cormorant, Phalacrocorax harrisi, represents an extreme case of this trade-off, having undergone secondary flightlessness in the isolation of the Fernandina and Isabela Islands. This review synthesizes the known morphological and physiological adaptations driving this evolutionary trajectory. Key adaptations include a significant reduction in pectoral keel and wing mass (wings reduced to approximately one-third the size of congeneric flying species), correlated with hypertrophied leg and tarsal musculature optimized for powerful, synchronized foot-propulsion underwater. This shift increases body inertia, facilitating efficient descent in shallow, near-shore environments (typical dives of 5–20 m) where it hunts benthic prey. While ecologically successful within its isolated niche, the loss of flight capacity renders P. harrisi highly vulnerable to external pressures, including El Niño events and introduced terrestrial predators. Understanding these specialized adaptations provides critical insights into the limits and consequences of evolutionary specialization within avian locomotion
Keywords
Cormorant, Obligate diving, Phalacrocorax harrisi, Flightlessness, Benthic foraging.
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© The Author(s) 2025. This article is published by International Journal of Zoology and Applied Biosciences under the terms of the Creative Commons Attribution 4.0 International License (creativecommons.org), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
