|
Vol. 52, 2013
Reproductive activity and advertisement calls of the Asian
common toad Duttaphrynus melanostictus (Amphibia, Anura,
Bufonidae) from
Bach
Ma National Park, Vietnam Binh V Ngo1* and Chung D Ngo2
1Department
of Life Sciences, National Cheng Kung University, No. 1 University
Road, Tainan City 701, Taiwan
2College of Education, Hue University, 34 Le Loi Road,
Hue City 47000, Vietnam
Abstract
Background: We examined differences
in reproductive activities and intraspecific variations in
advertisement calls of Duttaphrynus
melanostictus
(Schneider, 1799) that lives in a tropical region of central Vietnam.
The snout-vent length (SVL) of sexually mature males ranged from 50.2
to 70.3 mm, while that of females ranged from 65.2 to 97.3 mm.
Histological analyses of testes revealed that sperm was not present
throughout the year, indicating discontinuous reproductive activity for
adult males. Adult females were captured year-round, but reproductive
females were observed only during months of the auxiliary rainy season
(mainly April to July), indicating that females reproduce seasonally.
We also estimated levels of within-male variation of each call property
and the influences of the ambient temperature, humidity, and the SVL of
calling males on acoustic features.
Results: The call rate and pulse rate showed
intermediate levels of variation, whereas the dominant frequency and
call duration were the most stereotyped properties. One-way analyses of
variance for six acoustic properties showed that the call rate, pulse
rate, and rise time significantly differed (p < 0.05) among localities.
Advertisement calls were a series of groups of 56 to 244 (145 ± 54)
pulses with an average call duration of 26.722 s, an average pulse rate
of 11.69 pulses/s, and an average dominant frequency of 1.293 kHz. The
results of the multiple regressions for possible effects of
temperature, humidity, and SVL on the six acoustic properties indicated
that the dominant frequency, pulse rate, call duration, and rise time
were positively significant.
Conclusions: In Bach Ma National
Park, when air temperature in the recording area decreased to
<16.6°C, and advertisement calls of adult males virtually ceased in
all three populations.
Key words: Acoustics; Anurans; Bufo melanostictus; Breeding ecology;
Thua Thien-Hue.
*Correspondence: E-mail: nvb6868@gmail.com
|
