Saunders's gull: where and when to see them

Saunders's gull is a small East Asian coastal gull with a short black bill and specialized ties to intertidal wetlands. It breeds mainly along China's coast and spends the nonbreeding season farther south and elsewhere around East Asia. Vietnam is near the southern part of its regular wintering range, especially along northern coasts. Loss and alteration of tidal flats threaten both feeding habitat and the saltmarsh landscapes used for nesting.

Size

29–32 cm long

Weight

150–230 g

Lifespan

Not reliably established

Status

Vulnerable

Saunders's gulls often forage low over exposed mud, hovering briefly before dropping to seize prey. They also walk across tidal flats and gather at safe roosts when incoming water covers feeding areas. Breeding birds nest in loose colonies within coastal vegetation. Outside breeding, their daily schedule follows the tide more closely than the clock, with feeding opportunities shifting across a wetland as water levels rise and fall. They are quite skittish and easily disturbed, especially when roosting. When not feeding, they often rest in dense flocks with other small gulls and terns on sand spits or mud banks. Their communal roosting behavior provides safety in numbers from potential predators.

• It is the only living species placed in Saundersilarus.
• Its breeding hood is black, whereas black-headed gull has a dark brown hood.
• Hovering over mudflats is a characteristic feeding technique.
• Protecting high-tide roosts is important because feeding flats disappear beneath the water each tidal cycle.

Northern Vietnam offers the most plausible observation window during the cooler nonbreeding months, broadly November through March. Actual opportunities depend on local winter presence and tidal conditions. This period represents wintering habitat use, not the species' breeding season in Vietnam. During winter, large congregations can form at suitable sites, offering excellent viewing opportunities. The cooler months provide a more comfortable experience for observers. These periods are crucial for the species to refuel and rest before their northward migration.

The species depends on coastal mudflats, estuaries and saltmarshes, with nearby undisturbed places for high-tide roosting. Breeding occurs in low coastal vegetation above ordinary tidal flooding. Wintering birds may use managed coastal wetlands, but these do not fully replace natural intertidal habitat. This species is restricted to the East Asian Flyway. Its reliance on intertidal zones makes it highly vulnerable to habitat loss from coastal development and reclamation. Breeding colonies are typically found on secluded islands or mainland coastlines that remain undisturbed.

Small crabs and other intertidal invertebrates are important foods, supplemented by small fish and additional animal prey. Birds capture prey from exposed mud or shallow water. Their short bill and hovering approach help distinguish their feeding style from that of larger coastal gulls. They often specialize in small crustaceans like fiddler crabs, probing into the mud with their short bills. Their diet reflects the abundance of readily available invertebrates in their preferred estuarine environments. Occasionally, they will also take insects or small marine worms.

Common name

Saunders's gull

Scientific name

Saundersilarus saundersi

Animal group

Birds

Size

29–32 cm long

Weight

150–230 g

Lifespan

Not reliably established

Status

Vulnerable

Identification

Compared with black-headed gull, Saunders's gull is smaller with a shorter black bill, black legs and a distinctive limited black pattern on otherwise pale outer wings. Their dark hood is restricted to the crown and nape, extending only slightly below the eye, a key feature distinguishing it from other hooded gulls. The underparts are pure white, contrasting with the black primaries. Juveniles have a mottled brown back and a less defined hood.