Arginine vasotocin (AVT) and the mammalian homologue, arginine vasopressin 
(AVP), modulate vertebrate social behaviors, including vocalizations in male 
anurans. To study the impact of AVT and social stimuli on calling in male 
Xenopus tropicalis, we injected males with vehicle, 1 μg, or 10 μg AVT and 
recorded vocalizations under four social contexts (no stimulus, with male call 
playback, with a female, and with call playback and a female). More males called 
when injected with 10 μg AVT. Furthermore, calling males called only when paired 
with a female. We identified four call types: long fast trill; short fast trill; 
slow trill; or click. Next, we injected males with vehicle, 10 μg, or 20 μg AVT 
and recorded vocalizations with or without a female. AVT treatment did not 
affect calling in this experiment, but we confirmed that more males, regardless 
of AVT treatment, called when a female was present. Then we evaluated the effect 
of human chorionic gonadotropin (hCG) on male sexual behavior. 20 IU hCG 
elevated behavior compared to controls while the 10 IU hCG treatment group was 
not different from either treatment. Last, we examined the effect of AVT on 
hCG-induced reproductive behavior. Males were injected with 10 IU hCG or with 10 
IU hCG and 20 μg AVT. Males receiving hCG and AVT clasped and called 
significantly more than males receiving hCG only. Our results suggest that AVT 
and a female stimulus induce vocalizations in a male pipid anuran, X. 
tropicalis, and the interaction between gonadotropins and neurohormones 
influences reproductive behaviors in this anuran amphibian.