Red-throated diver

The red-throated diver (Gavia stellata) is found all the year round in the far northwest of Ireland and the highlands and islands of Scotland. It is also found in northern Europe, Russia and North America. It is a coastal bird except during the breeding season when it moves inland to small lakes on upland moors, returning to the coast in winter in small flocks of up to 100 birds.

Adult birds are around 21-23 inches (53-58 cms) in length, which is similar to that of the mallard. Summer plumage is a grey body, velvety grey head and dull red throat patch. Winter plumage is grey-brown and white with white spots on the back. Males and females are similar in appearance.

The bird is well-adapted to feeding at sea or on inland lakes. It swims low in the water with the bill pointing slightly upwards and will submerge if alarmed. It will chase fish underwater or scoop shellfish from as deep as 30 feet (9 metres).

Favourite marine fish are herring, cod, sprats and sand-eels. Freshwater fish include small salmon, trout and roach.

In flight, red-throated divers have rapid wingbeats with the wings lifted high as the head and neck move and down. Although red-throated divers can take off easily from the surface, landing on water can be awkward and noisy due to the legs being set far back on the body.

Red-throated divers are generally silent, although during the breeding season this is not the case. High-pitched wails are often heard as the birds assemble at the breeding grounds and compete for the best sites. The wails were once thought by local people to signify the approach of bad weather, hence the name of “rain goose” that was sometimes used for this species.

Nests are heaps of water plants or moss, either on the shoreline of lochans (small freshwater lochs) or floating on the surface. One or two eggs are laid, these being incubated mainly by the female for 26-29 days. The young leave the nest after only a day or so, but continue to be fed by their parents for about 50 days. They will themselves be ready to breed after two or three years.

Numbers of red-throated divers have increased since they ceased to be persecuted in the 19^th century, but are still not large. There may be a total winter population of about 5,000 birds, but it is noticeable that the numbers on the Shetland Islands have declined since the early 1980s by about a third.

© John Welford