Jg. Wong et Da. Waters, The synchronisation of signal emission with wingbeat during the approach phase in soprano pipistrelles (Pipistrellus pygmaeus), J EXP BIOL, 204(3), 2001, pp. 575-583
Previous studies have shown that, during search flight in bats, wingbeat, r
espiration and echolocation are synchronised in a 1:1. relationship. An eff
iciently integrated locomotor-respiratory system enables bats to produce in
tense echolocation signals at little or no cost above that required for fli
ght, In this study, we investigated the coupling of wingbeat with echolocat
ion in the laboratory during approach flight in soprano pipistrelles (Pipis
trellus pygmaeus) using high-speed digital video at 250 and 500 frames s(-1
). We found that soprano pipistrelles most commonly produce single or doubl
e pulses per wingbeat, Single pulses per wingbeat occurred in two alternati
ve positions: immediately before the end of the upstroke or after the start
of the downstroke. Double pulses per wingbeat were emitted in the same win
gbeat positions on the upstroke and the downstroke, as in single pulses per
wingbeat, We suggest that, during approach flight, the coupling of more th
an one echolocation signal with a single wingbeat and expiratory cycle allo
ws echolocation to remain energetically economic. When soprano pipistrelles
approached a Perspex disc target, an increase in mean repetition rate was
achieved by producing an extra pulse per wingbeat, Finally, we hypothesise
that the bat's approach to potentially interesting targets in the same hori
zontal plane as it's flight path, i.e. during flapping flight, may be chara
cterised by the production of double pulses per wingbeat, resulting in a un
ique pattern of echolocation pulse intervals.