Behavioural Diversity: Conditional Movement Tactics in the Ruff (Calidris pugnax)

Understanding the movement behaviour of male ruffs (Calidris pugnax) during the breeding season requires integrating recent telemetry data with long-standing theory on conditional reproductive strategies, lek dynamics, and behavioural polymorphism. A large-scale tracking study revealed extensive within-season movements among many males, with individuals visiting 1 to 23 sites, but also documented prolonged residency, with site tenures exceeding 40 days. Such variation is not contradictory but expected in a species whose reproductive system combines genetically fixed alternative strategies, governed by a supergene, with flexible conditional tactics expressed in response to ecological and social cues. Here, I synthesize movement ecology, state-dependent decision models, lekking theory, and previous empirical work to show that spatial behaviour in ruffs reflects a continuum of tactics rather than a homogeneous nomadic mode. Telemetry data thereby enrich our understanding of how individuals navigate fluctuating environments, competitive pressures, and mating opportunities. Embracing behavioural heterogeneity is essential for interpreting movement patterns and for understanding how reproductive diversity evolves and is maintained in lekking systems.