Temporal Feasibility Constraints on Wingbeat-Call Synchrony in Actively Echolocating Bats.

Echolocating bats operate within a closed sensorimotor loop in which call emission, echo reception, sensory processing, and motor response are linked by finite propagation delays and bounded response times. Although synchrony between wingbeats and call timing is frequently observed, it remains unclear when such coordination is temporally feasible and when it must necessarily break down. Here, I develop a constraint-based framework formalising how temporal feasibility limits shape wingbeat-call coordination during active echolocation. Building on the responsivity framework, the analysis derives explicit conditions under which call emission remains phase-locked to a cyclic motor rhythm, and identifies regimes in which phase locking becomes progressively infeasible as acoustic delay shrinks and call rate rises during prey approach. Simulations across three motor-control configurations-fixed wingbeat frequency and excursion, dynamically adjusted frequency, and dynamically adjusted frequency and excursion-show that transitions from synchrony to asynchrony arise as necessary consequences of delayed feedback and bounded motor dynamics, rather than discrete changes in behavioural strategy. Increasing motor flexibility extends the synchrony-permissive range of call rates but does not eliminate the feasibility boundary. Simulation ensembles spanning biologically plausible parameter combinations confirm that regime transitions are robust and that asynchronous call phases exhibit structured clustering near the feasibility boundary. Empirical observations of transient decoupling during prey pursuit and the terminal buzz are consistent with these predicted transitions. The results identify temporal feasibility as a governing constraint on echolocation behaviour, clarify how apparent closed-loop coordination can arise without tight motor coupling, and generate testable predictions for when and why wingbeat-call synchrony must fail during prey capture.