Males call more from wetter nests: effects of substrate water potential onreproductive behaviours of terrestrial toadlets

Laboratory studies of terrestrial-breeding frogs have demonstrated that wet ter substrates produce fitter offspring but the relevance of substrate wetn ess to adult reproductive strategies is unknown. I hypothesized that male t oadlets (Pseudophryne bibronii) would select wetter areas for nesting and w ould advertise wet nests strongly, and tested these predictions by manipula ting water potentials at a breeding site. Males preferred to nest in the we ttest areas, and called at greater rates on almost twice as many nights as males occupying drier nests. Overall, males that mated called on significan tly more nights than unmated males. Hence, because males occupying wet nest s called more, they also mated more and in 19 out of 20 cases, oviposition occurred in wet nests that were suitable for embryonic development. Males o ccupying drier nests may have risked dehydration by calling, and so were le ss able to signal to females. Hydration slates therefore have the potential to influence the reproductive success of terrestrial male frogs.