Lek (animal behavior)
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A lek (from Swedish lek, a noun which typically denotes pleasurable and less rule-bound games and activities) is a tournament (the males of certain species of animals for the purposes of competitive mating display), held before and during the breeding season, day after day, when the same group of males meet at a traditional place and take up the same individual positions on an arena, each occupying and defending a small territory or court. Intermittently or continuously they spar with their neighbours one at a time, or display magnificent plumage, or vocal powers, or bizarre gymnastics...
Though they have territories, yet they have a hierarchy with the top-ranking males typically placed in the middle and ungraded lesser aspirants ranged outside. Females come to these arenas in due course to be fertilized, and normally they make their way through to one or other of the dominants in the centre. Two main types are distinguished, classical leks and exploded leks. In classical leks, individuals are in sight of each other, physical contest is not infrequent or even prevalent in some (mainly shorebird and gamebird) species. Exploded leks rely on vocal signals, the most famous example is the "booming" behaviour of the Kakapo, where distances between individuals can be up to many kilometers due to the far-carrying sound. Indeed, female kakapos seemed to often have considerable problems to locate mates as the species became extinct on mainland New Zealand; this was a significant cause for the insufficient reproduction rate which made this species to go extinct outside human care for some years.
The term was originally used most commonly for Black Grouse (orrlek) and for Capercaillie (tjäderlek), and lekking behaviour is quite common in birds of this type, such as Sage Grouse. However it is also shown by birds of other families, such as the Ruff, Great Snipe, Musk Ducks, Hermit hummingbirds, Manakins, birds of paradise and the Kakapo, by some mammals such as the Uganda kob (a waterbuck) and by some species of fish and even insects like the midge and the Ghost Moth. The rut of deer is also very similar. There is some dispute among ethologists as to whether the lekking behaviour shown by animals of widely different groups should really be treated as the same, and in particular whether similar selective pressures have led to their emergence.