Dive in with both feet

Do you know your great crested grebe from your little grebe? Your red-throated from your great northern diver? Marianne Taylor gets to grips with these masters of the underwater world

IT’S up, it’s up—quick! Oh, no, it’s dived again.’ Such is the lament of the birdwatcher attempting to point out a diver or grebe to a companion. Whether the subject is a stately great northern diver floating off a picture-perfect Hebridean beach or a diminutive black-necked grebe playing hide and seek among a flock of ducks in the deepest reaches of an Essex reservoir, the challenge is the same. These masters of the underwater world seem to shun the feeling of air on their feathers, such is their eagerness to immerse and immerse again.

Of all the UK’s waterbirds and seabirds, few are as well adapted to swim underwater as divers and grebes. Their stout legs, with webbed toes in divers and lobed in grebes, sit so far back on their bodies that they can barely walk or stand, hence the local nickname of ‘arse-foot’ for some species. How-ever, this extreme foot position provides an extra-powerful ‘outboard motor’ to drive their fast underwater fish-chases.

Divers and grebes are not closely related, as was once thought: divers are an early offshoot of the same lineage as penguins, whereas grebes count flamingos as their closest cousins. However, the two groups’ anatomy, ecology and behaviour are remarkably similar. Our three regularly seen diver species and five grebes nest on the edges and islands of lakes and are strongly monogamous, sharing incubation and care of the chicks, which can swim from hatching, but need to be fed for many weeks. Because of the commitment they will need from one another for a successful breeding season, the male and female rigorously test each other’s attentiveness, fitness and partnership skills through dramatic and often noisy displays, showing off their bright breeding colours. After breeding, they become drabber and quieter, with many dispersing to larger lakes or the sea.