British Wildlife of the Week

Ruff

Every year, male ruffs undergo one of the most spectacular avian transformations in the world. During winter, they are birds of subdued browns and greys, but as the breeding season approaches, they develop colourful summertime finery, becoming extravagantly plumaged wading birds. As you can see in the picture above, they grow ornamental erectile head plumes and broad, feathery neck ruffs, reminiscent of the exaggerated collars that became fashionable in European courts from the mid-16th to the mid-17th centuries. The various elements of the males’ breeding plumage differ enormously in both shape and colour. In fact, ruff have, perhaps, the most variable plumage of any wild bird in the world. No two males look alike, allowing each to be recognisable as individuals.

During the breeding season, males gather at traditional display grounds, hoping to attract females. Each male has his own stage from where he will display, but all of them are sufficiently close together for the choosy females – also known as ‘reeves’ – to move easily from one to another to make their comparisons. An aggregation of males engaging in competitive displays such as this is known as ‘lekking’. Lekking is most commonly seen among game birds such as grouse and prairie chickens, although several other types of bird – not to mention mammals such as fruit bats and kob antelope, along with a few species of amphibian, fish and insect – also practise it [1].

Male ruffs have three different mating strategies, each of which is associated with a particular, genetically determined plumage pattern. Those with dark plumage, for example, defend their own small territories within the lek. Their ritualistic displays are typically silent but elaborate, involving lots of jumping, wing fluttering, and erecting their spectacular ruffs. These territory-holders remain in the lekking ground for the whole season and display a high degree of aggression towards one another. Though they usually just eye each other up from their own personal patch of ground, a metre or so apart, they occasionally resort to physical violence, jumping into the air to strike out at one another with their long legs.

The females, which are smaller, with none of the fancy, opulent plumage, enter the communal grounds and inspect the displaying males. However, the majority of the males will be disappointed, for the reeves tend to head to the individual in the very centre of the lek, for he invariably holds the best territory. The owner of this prime spot enjoys regular matings, but he is constantly challenged by his neighbours.

Paler-plumaged ‘satellite males’, meanwhile, do not occupy their own territories and often move from lek to lek. Their strategy is to lurk in the background and attempt to mate with females visiting the territories occupied by dark-plumaged males. Surprisingly, the resident ruffs tolerate the satellite birds because, although they are competitors in the mating game, the presence of both types of male seems to attract additional reeves.

The third and rarest type are males that permanently mimic females. Lacking the flamboyant plumage of the other two types, these female-like morphs can wander with impunity among the reeves. They look and act like females to such a degree that a male in full breeding garb may well mount and try to mate with them. But for the female-mimicking males, such couplings are clearly worth it in their bid to increase their chances of sneaking copulations with the reeves.

More than half of reeves mate with, and have clutches fertilised by, multiple males, and individual females mate with males of both main behavioural morphs more often than expected by chance. But no matter what mating strategy a ruff uses, his involvement with a female ends just as soon as he has mated with her. He will immediately begin looking for more mating opportunities, while the female must incubate the eggs and rear the chicks by herself.

In the next British Wildlife of the Week, we’ll be looking at another lekking species: a very impressive bird that happens to be one of my absolute favourites – the capercaillie.

^{_{[1] In almost all known species that practise lekking, it is the males that gather en masse to display to females. Leks in which females display to males are, as far as I can tell, known from just two species: the worm pipefish (which, like its seahorse relatives, is well-known for its sex role reversal) and a single type of fly.}}