Ml. Dyson et al., THE EFFECT OF CHANGES IN THE RELATIVE TIMING OF SIGNALS DURING FEMALEPHONOTAXIS IN THE REED FROG, HYPEROLIUS-MARMORATUS, Animal behaviour, 48(3), 1994, pp. 679-685
In anurans the properties of individual males' calls can change marked
ly during a single bout of calling. Females will therefore be confront
ed with an array of signals that change in relative attractiveness ove
r time and, consequently, may be stimulated to approach several males
before initiating amplexus. This would increase the time spent in the
chorus and therefore, the costs associated with finding a mate. These
costs may be minimized if, at some point of 'decision', a female's res
ponse to a male becomes irreversible, such that any subsequent changes
in dynamic call features are ignored. To test this females were prese
nted with two identical calls in a leader-follower call pattern and th
en the timing of the calls after the initiation of a response to the p
referred leader was switched. If call timing was switched when females
were within 2 m of the leader, they changed course and tracked the so
urce of the leading call. However, when calls were switched when femal
es were 2 m away, only some females changed course. A second experimen
t tested whether females 'lock into' static features such as dominant
frequency. When a high frequency leading call was switched to a follow
er and a low frequency call to a leader, females tracked the source of
the leading call, disregarding call frequency. The tendency was weake
r when a high frequency follower was switched to a leader. The idea th
at the initiation of a response to a male renders females less respons
ive to more attractive calls that may arise is not supported.