Arctic Tern: The Ultimate Long-Distance Migrant

The Arctic Tern (Sterna paradisaea) holds the animal kingdom's longest migration record—~70,000–90,000 km (44,000–56,000 mi) annually, pole to pole.

Speed & Flight Mechanics

• Cruising speed: 35–45 km/h (22–28 mph) — efficient, not fast.
• Maximum sprint: 60–70 km/h (37–43 mph) — chasing prey, escaping skuas.
• Strategy: Flap-gliding — burst flaps, then glide on stiff wings. Low energy cost. Tailwind exploitation (follows prevailing winds).
• Non-stop segments: Up to 5,000 km over open ocean (Atlantic crossing).

The Migration Loop

1. Breeding (May–Jul): Arctic/subarctic coasts — Greenland, Iceland, Svalbard, Alaska, Canada.
2. Southbound (Aug–Oct): Follow Atlantic or Pacific flyways. West Atlantic birds cross to Africa; East Atlantic birds hug coast.
3. Wintering (Nov–Mar): Antarctic pack ice edge, Weddell Sea, Ross Sea — 24-hr daylight, krill abundance.
4. Northbound (Apr–May): More direct, faster — urgency to claim nest sites.

Why So Far?

Perpetual summer = perpetual food. Arctic summer: insects, fish. Antarctic summer: krill. The tern follows the "eternal summer" band, experiencing more daylight than any creature.

Physiology

• High aspect-ratio wings (long, narrow).
• Low wing loading.
• Efficient fat metabolism (pre-migration hyperphagia: 50% body mass as fat).
• Salt glands (drink seawater).
• Unihemispheric sleep (suspected) — sleep flying.

Threats

• Climate change: phenology mismatch (food vs. arrival), sea ice loss.
• Plastic ingestion, bycatch, colony disturbance.
• IUCN: Least Concern (global pop ~2M), but declining in parts of range.

The Arctic Tern doesn't "fly fast." It flies far, efficiently, relentlessly—a 30-gram bird circling the planet yearly.