Osprey Migration Stopover: Terns Defend Their Colony Against a Hungry 2026

During osprey migration, a hungry osprey stopping to feed can face fierce resistance from local terns defending their colony. In a recent country diary entry, a boat trip off Fowley Island turned into a front-row seat to this avian drama. The autumnal sunlight gilded the sea as our boat drifted off Fowley Island, a small, uninhabited tidal saltmarsh between Thorney Island and Hayling Island. A colony of grey seals lay sprawled along the intertidal mudflats, their size and prominent, sloping Roman noses making them easily distinguishable from the more lithe, cat-faced common seals that also inhabit the harbour. Two sub-adults were tumbling and splashing in the shallows, play-fighting with the exuberance of puppies. They mouthed and nipped at each other’s heads and necks, lunging and rolling over one another before disappearing beneath the waves, only to pop up again in a spray of water and resume their boisterous tussle. These playful interactions are a form of social bonding, but they also serve as a rehearsal for future dominance contests. As we passed through the Sweare Deep tidal channel, the boat slowed to let us watch a flock of sandwich terns plunge-diving for silvery bait fish driven to the surface by predatory sea bass. Glancing over my shoulder, I noticed a much larger bird approaching from the north. At a distance, it might have been mistaken for a black-backed gull, but its long, crooked wings, bent at the “wrist” into a distinctive M shape, gave it away: an osprey, stopping off to fuel up on its migration. As I called out to alert my boatmates, the osprey dropped feetfirst towards the water to snatch a fish, but the terns had other ideas.

Osprey Migration Stopover: A Critical Resting Point

Ospreys are long-distance migrants, traveling thousands of miles between breeding grounds in Europe and wintering areas in Africa. During these journeys, they rely on stopover sites rich in fish to replenish their energy reserves. Fowley Island and the surrounding harbour clearly offer such a bounty. But as this encounter shows, ospreys don't always get a free meal.

Terns Defend Their Colony

Sandwich terns, with their black caps and yellow-tipped bills, are highly territorial during the breeding season. When an osprey approached, the terns immediately switched from feeding to defense mode. They mobbed the larger bird, diving at it and calling loudly. This behavior, known as mobbing, is common among colonial seabirds. It serves to drive away potential predators and protect eggs or chicks. Even though the osprey was after fish, not tern chicks, the terns weren't taking any chances.

Seal Social Bonding: Playful Practice for Dominance

The grey seals we observed were engaged in what looked like pure play. But these interactions are more than just fun. They help establish social bonds and hierarchies within the colony. Young seals practice fighting skills that will be crucial later in life when competing for mates or territory. The harbour, with its mix of grey and common seals, provides an ideal setting to observe these behaviors.

Comparison of Seal Species

To better understand the seals mentioned in the diary, here's a quick comparison:

Key Takeaways from This Wildlife Encounter

• Osprey migration relies on stopover sites with abundant fish.
• Terns defend their colony through mobbing behavior, even against larger birds.
• Seal social bonding includes play-fighting that prepares young for future dominance contests.
• Coastal habitats like Fowley Island are vital for multiple species during migration and breeding seasons.
• Observing such interactions offers insights into animal behavior and ecology.

FAQ

This country diary entry captures a fleeting but powerful moment in nature. It reminds us that even in protected harbours, wildlife faces constant challenges. The osprey's migration is a marathon, and every stopover counts. The terns' vigilance is a testament to the fierce drive to protect their young. And the seals' playful antics are a window into the complex social lives of marine mammals. Next time you're near a coastal saltmarsh, keep your eyes peeled—you might witness a similar spectacle.