The introduced Cane Toad Rhinella marina has recently expanded its range into the monsoonal north of Australia near Darwin, Northern Territory. Aggregated toads were collected toward the end of the prolonged dry season from an isolated and localized occurrence of moist soil, where they were observed in typical water absorbing postures. Water potential of the moist soil (−31 kPa) was sufficient that toads could extract liquid water via the ventral pelvic patch, but surrounding dry soils with water potentials lower than −8,000 kPa could not be used as moisture sources. High mean plasma (358.5 mOsm kg−1) and urine (353 mOsm kg−1) osmolality values are indicative of dehydration, and high urea concentrations in plasma (109 mmol L−1) and in urine (237 mmol L−1) demonstrate accumulation and retention of waste nitrogen. All parameters differed markedly from those of fully hydrated toads in the laboratory and from active animals collected in the wet season. The urine osmolality of wet season individuals (mean ± SD: 118.9 ± 76.4 mOsm kg−1) was intermediate compared to the laboratory hydrated animals and the dry season sample, but plasma osmolality and urea concentrations were similar to fully hydrated toads. Differences in body fluid osmolality reflect the availability of soil and surface moisture in the environment in the wet and dry seasons. The need to access residual moisture sources during the late dry season is likely to limit Cane Toad movement and resulted in the aggregation of toads at the rehydration site. This enforced aggregation potentially facilitates effective control of toads at a local scale.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.