No. 126 on our checklistWhiskered Tern (Chlidonias hybrida)

On a summer morning on any lake of the Danube Delta covered with water lilies, the air above the water is full of small grey terns. They fly slowly into the wind, stop, hover, drop to the surface and rise again with a dragonfly or a tiny fish. This is the Whiskered Tern, one of the most numerous terns of the Danube Delta, and it lives its whole summer on the floating leaves of the lakes.

When to see it in the Danube Delta and Dobrogea

1. JanAbsent
2. FebAbsent
3. MarAbsent
4. AprAbundant
5. MayAbundant
6. JunAbundant
7. JulAbundant
8. AugAbundant
9. SepAbundant
10. OctRare
11. NovAbsent
12. DecAbsent

Status here

Summer breeder.

IUCN Red List

Least Concern

Our checklist

No. 126 of 385 · see the full checklist

How to recognise it

In summer the adult has a black cap down to the eye, and below it a clean white band across the cheek, the “whisker” that gives the bird its name. The rest of the body is grey: the back and wings pale silver grey, the breast and belly darker, smoky grey, only the area under the tail white. The bill and the legs are dark red. It is a little bigger and paler than the other two marsh terns of the Danube Delta.

From late summer the adults turn white below and keep only a black patch behind the eye and a streaked crown, and then they are easy to confuse with the other marsh terns. Young birds have a brown, scaly back. In spring the White-winged Tern is the easy one: a black body with white wings. The Black Tern has a black head and body and grey wings, while the Whiskered Tern always keeps its white cheek.

Feeding and nesting

The Whiskered Tern does not dive like the sea terns. It hunts low over the water, hovers for a moment and picks its prey from the surface or from the air: dragonflies and other large insects, small fish, tadpoles and small frogs. It also hunts over wet meadows and rice fields.

It nests in colonies on the water itself. Each pair builds a small floating platform of wet plant stems, usually on a raft of water lily leaves or other floating plants, in quiet lakes and channels with little current. The female lays usually two or three eggs, and both parents incubate them for about three weeks. The colonies are noisy, and the adults attack anything that comes too close, including people in a boat.

Where to see it in the Danube Delta

Whiskered Terns arrive from Africa in April and leave in September; a few stay until October. They are everywhere where there are water lilies: on the lakes and channels around Mila 23, Fortuna, Isac, Uzlina and Gorgova, and on the quiet backwaters of the large lakes. Our checklist marks it abundant from April to September. In the breeding season it is one of the birds you see most on any trip, and it is one of the best subjects for photography from a boat, especially in flight.

You will see it every day from May to August on our 5 day birdwatching tour in the Danube Delta and on our 5 day wildlife photo tour, where there is time to wait for the best light and the best flight.

Interesting facts

• Thousands of pairs. The Danube Delta and the Razim Sinoe lagoons hold an estimated 5,000 to 6,000 breeding pairs, according to the checklist of the Danube Delta Biosphere Reserve published in 2023, and 30,000 to 50,000 birds pass through on migration.
• A nest that floats. The nest is a small heap of wet plants that floats on the water lily leaves. When the water rises after rain, the nest rises with it.
• A “hybrid” by name. Hybrida means “hybrid” in Latin. To its first describers the bird looked halfway between the sea terns and the marsh terns.
• Moving north. In Poland the Whiskered Tern grew from about 40 pairs in 1990 to more than 1,600 in 2007, helped by birds coming from the east. The species is spreading north in Europe.
• Brave parents. Adults dive at herons, harriers and even boats that pass too close to the colony, calling loudly with a harsh, rasping voice.

Status and threats

The Whiskered Tern breeds in southern and eastern Europe, Asia, Africa and Australia and is listed as Least Concern by the IUCN. It depends on shallow, quiet water with floating vegetation, so it suffers when wetlands are drained or when water levels change suddenly in the breeding season.

In the Danube Delta today the greatest threat to nature is speed boats. The Whiskered Tern’s nests float on the water, and the waves of a fast boat wash them off the lily leaves or sink the eggs. This is why our boats move slowly in the channels.