INFLUENCE OF CONSPECIFICS AND ROAD NOISE ON THE PROPERTIES OF THE
ADVERTISEMENT CALL OF PHYLLODYTES LUTEOLUS (ANURA, HYLIDAE)
Abstract
Acoustic communication in animals can be affected by multiple biotic
(intra and interspecific) and abiotic (e.g., wind and rain) natural
noises. In addition, human beings produce additional novel sources of
noise, which can reduce or inhibit the reception of acoustic signals by
conspecifics, leading to behavioral changes. In this study, we
investigated whether sound of conspecifics and road noise additively
affect the acoustic parameters of the advertisement call of males of a
Yellow Heart-tongued Frog (Phyllodytes luteolus). We hypothesized that
males that vocalize in larger choruses (many males) and in areas close
to highways (anthropic noise) will increase their temporal and spectral
acoustic parameters, respectively, to avoid acoustic signal masking. We
recorded the vocalizations of 38 males in environments close (N=18) to
and distant (N=20) from highways in different social contexts (many or
few individuals in the chorus). Contrary to our expectation, the results
indicated that individuals exposed to road noise had lower dominant
frequency calls than those from natural areas, and that the density of
males in the chorus had no influence on the acoustic parameters.
Furthermore, we found a positive relationship between body size and
intensity, indicating that larger individuals can emit calls that can
reach greater distances. The advertisement call of Phyllodytes luteolus
has a high dominant frequency, with little overlap with the frequency of
anthropic noises (roads), which may explain its presence and
reproductive success of this species in bromeliads from urbanized areas.