Can seagulls swim underwater?

Seagulls are a familiar sight at beaches, harbors, and coastal towns, circling overhead or fighting over food scraps. Their ability to fly gives them access to food sources like discarded takeaway and fishermen’s catches. However, seagulls sometimes plunge below the surface of the water to catch prey. This raises the question – can seagulls actually swim underwater?

The underwater skills of seagulls

Many people assume that when seagulls go underwater they are simply floating on the surface and dipping their heads below to catch food. However, seagulls have some impressive aquatic skills and can actively propel themselves and navigate while submerged.

When going underwater, a seagull will close its nostrils to keep water out. Air sacs under its skin provide buoyancy, while webbed feet propel it. Seagulls have waterproof plumage that retains air and reinforces their insulation and floating ability. Their eyes have special fluid-filled membranes allowing clear vision underwater. Some gland secretions also waterproof and condition the feathers. S eragulls can alter the angle of their toes to steer through the water in pursuit of prey. Studies show seagulls can remain submerged for over 20 seconds during dives.

So while floating on the surface, seagulls are quite buoyant. But they can overcome this buoyancy to swim downwards. Combining aerial mobility with aquatic diving allows seagulls to exploit food sources inaccessible to many other birds.

Why seagulls swim underwater

Swimming underwater allows seagulls to catch fish, shrimp, marine worms, and other aquatic prey. It expands their foraging range and flexibility. Major reasons seagulls swim underwater include:

• Catching fish – Plunge diving to grab fish near the surface or swimming down to pursue fish in shallow water.
• Foraging in tide pools – Diving to pick aquatic invertebrates out of rocky tide pools.
• Feeding on discards – Sinking down to grab edible scraps discarded by boats or fishermen.
• Escaping danger – Diving to evade predators such as eagles, falcons, or gulls of other species.

Swimming underwater allows seagulls to exploit food sources unavailable to terrestrial species. Even at harbors or wharves, much discarded or spilled food sinks below the surface, requiring diving skills to access.

Limitations of seagulls underwater

Despite their swimming adaptations, seagulls do have limitations on how deep, how long, and under what conditions they can swim underwater:

• Depth – They seldom dive below several meters deep due to pressure effects.
• Duration – Continuous dives last no more than 30 seconds since they need air.
• Visibility – Turbid water blocks their underwater vision.
• Buoyancy – Plumage adaptations make sinking underwater difficult.
• Energy cost – Diving is energetically expensive for flying species.

As mainly aerial species, seagulls are not optimized for deep or prolongued diving. Their underwater capabilities complement their aerial mobility rather than replace it. But combined, these capacities grant seagulls great flexibility in exploiting coastal food sources inaccessible to either terrestrial or aquatic species alone.

Seagull species and underwater swimming

There are over 50 species in the seagull family Laridae, occupying coastal habitats worldwide. Their underwater capabilities vary:

Proficient diving species

• European herring gull – Plunge dives from up to 20m high. Swims underwater down to 4m deep.
• Great black-backed gull – Dives from a height of 1-6m. Swims underwater with powerful kicks.
• Western gull – Makes shallow dives to feed in kelp beds and tidepools.

Occasional diving species

• Black-headed gull – Seldom dives, mainly skims surface.
• Franklin’s gull – Occasionally dives up to several feet deep.
• Laughing gull – Infrequently dives below surface, prefers aerial food.

The most proficient diving gull species are larger bodied and primarily coastal. Smaller or inland species less adapted to swimming underwater may do so only opportunistically. But all swimming enhances the flexibility of seagulls in exploiting aquatic food sources.

How seagulls swim underwater

Seagulls have evolved specialized adaptations allowing them to overcome their natural buoyancy and successfully swim underwater:

• Waterproofing – Feathers coated in preen oil shed water and maintain air layers for insulation and buoyancy.
• Nictitating membranes – Transparent third eyelids protect eyes while maintaining visibility.
• Salt glands – Excrete excess salt from marine food and water through nostrils.
• Webbed feet – Toes linked by webbing provide propulsion like paddle wheels.
• Reversible toes – Special tendons allow toes to pivot backwards to reduce drag on uplift.

Through these adaptations, seagulls overcome the constraints of aerial species foraging in aquatic environments. This expands their flexibility in exploiting coastal habitats.

Underwater behavior while swimming

Seagulls display characteristic underwater behaviors while swimming:

• Swimming downward against natural buoyancy.
• Propelling with webbed feet, sometimes paddling with wings.
• Streamlining body alignment to reduce drag.
• Closing nostrils and eyes just before submerging.
• Opening eyes wide underwater to spot prey.
• Grabbing prey in beak then ascending rapidly.
• Releasing air bubbles trapped in feathers during ascent.

Mastering these behaviors allows seagulls to dive below the water surface and swim effectively to catch prey. The ability to transition rapidly between aerial and aquatic environments underlies their flexible foraging strategy.

Conclusion

Seagulls are highly adaptable foragers, exploiting both aerial and aquatic environments. Their ability to actively swim underwater expands their coastal niche and complements their aerial mobility. Species such as herring, black-backed, and western gulls are the most proficient divers. However, all seagulls can swim underwater to some degree by overcoming their natural buoyancy. Their amphibious nature underlies seagulls’ success as opportunistic feeders along coasts worldwide.