Behavioural Ecology of the Little Bustard: Sexual Selection and Mating Systems

Abstract

In this chapter, we focus mainly on the behavioural ecology of the little bustard (i.e. how behaviour relates to ecology and evolution), with particular emphasis on breeding behaviour, sexual selection and mating systems, as well as their relevance for little bustard conservation. We discuss the evolutionary forces that drive the species’ lekking behaviour and its variations under the framework of sexual selection theory. We also discuss other less studied aspects of little bustard behavioural ecology (sperm competition, personality traits, and parent–offspring conflicts). The little bustard mating system is described in most localities as an exploded lek strategy but can be quite flexible, and a variety of situations ranging from resource-based monogamy to classical leks have been suggested. Several non-exclusive theoretical models of lek formation have been proposed and are all consistent, to some degree, with the little bustard’s lekking behaviour. However, two models (hotshot and black hole) seem particularly appropriate to describe the little bustard mating system at different spatial scales. On larger scales, female mobility and harassment by individual males may induce male aggregation as described by the black hole mechanism. At smaller scales, female preference for particularly attractive males (hotshot) or certain lek sizes may induce an initial clustering, which would be further maintained and structured as a result of the hotshot mechanism. Overall, the female choice seems to be based on multiple criteria (male snort call rate, plumage traits and displays). Habitat quality and resources within male territories are variable, and evidence suggests that these determine male settlement, but no evidence supports a decisive role in mate choice. Evidence regarding sperm competition in little bustard is scarce as well as contradictory. The apparently long time elapsing between mating and laying would allow for potential cryptic female choice through sperm competition, but the apparently low rate of copulation suggests that sperm competition might not be intense in little bustards. Evidence from decoy experiments and observations suggests that male and female little bustard behaviours (displays, behaviour during captures) are variable but consistent (repeatable) within individuals and may define individual personalities. These aspects of little bustard behaviour, and their relevance for conservation, also deserve further study.