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Herpetological research involving amphibians is increasingly using mark and recapture methods, employing various techniques such as toe-clipping and visible implant alphanumeric tags. Visual Implant Elastomer (VIE) is a new method available for herpetological surveys, involving a coloured dye inserted into the epidermal skin surface of frogs. Previously, there has been only one study which demonstrated that the VIE method does not generate a significant physiological stress response (using a faecal glucocorticoid method) in a captive amphibian species. Physiological stress can also be quantified non-invasively using urinary corticosterone metabolite (UCM) enzyme-immunoassay in amphibians. In this study, we tested the physiological stress response of a common amphibian species, wild caught Asian toads (Duttaphrynus melanostictus), by comparing UCM responses to capture handling, sham control or VIE marking method. Adult males (n = 38) were captured and sampled for baseline UCM (t = 0 h) then marked either using the VIE or sham (saline control), or only handled during capture. Subsequently, urine samples were collected at t = 2, 12 and 24 h for toads within each group. UCM levels were quantified using an enzyme-immunoassay (EIA) to determine differences among treatment groups and over time following capture. Toads generated acute stress responses to all three groups, showing a change in UCMs between baseline samples, 12 h, and 24 h samples. The mean UCM levels were not significantly different between the VIE method and the control groups (capture handling or sham operated). These results indicate that VIE method of tagging is no more stressful than routine handling of amphibians, hence in this context, the method does not have any additional welfare implications. Future research should explore the limitations of VIE tagging for long-term mark recapture studies, however, our current findings support its application as a minimally-invasive method for marking amphibians. [ABSTRACT FROM AUTHOR]

Ontogenetic changes in kin-recognition behavior, effect of social environment on kin-recognition ability, and use of visual and chemical cues in kin recognition have been studied in tadpoles of Bufo scaber after rearing them with kin, in mixed groups, or in isolation from Gosner stage 12 (gastrula). By use of a rectangular choice tank the tadpoles were tested for their ability to choose between (a) familiar siblings and unfamiliar non-siblings, (b) unfamiliar siblings and familiar non-siblings, and (c) unfamiliar siblings and unfamiliar non-siblings. When tested without any stimulus groups in the end compartments of the tank, random distribution was observed for the tadpoles and no bias for the apparatus or the procedure. In the presence of kin and non-kin in the end compartments, significantly more tadpoles spent most of their time near kin (familiar or unfamiliar) rather than near non-kin during early larval stages, up to stage 37. After stage 37 (characterized by the differentiation of toes), test tadpoles showed no preference to associate with kin, suggesting an ontogenetic shift in the kin-recognition ability in B. scaber. In experiments involving selective blockade of visual or chemical cues the test tadpoles preferentially associated near their kin on the basis of chemical rather than visual cues. These findings suggest that familiarity with siblings is not necessary for kin recognition and that kin-recognition ability is not modified after exposure to non-kin by mixed rearing. The findings for B. scaber indicate a “self referent phenotype matching” mechanism of kin recognition which is predominantly aided by chemical rather than visual cues. [ABSTRACT FROM AUTHOR]

Abstract: Tadpoles of the tropical bicolored frog, Clinotarsus curtipes are unique in having parotoid glands secreting a white viscous fluid and are structurally similar to granular glands from other amphibians. To ascertain the involvement of these glands and their secretion in predator deterrence, it was tested against a predatory fish, Clarias gariepinus, using a paired choice behavioral assay. The results showed that the fish avoid eating C. curtipes tadpoles when paired with tadpoles of a sympatric species, Sylvirana temporalis. While the fish fed on C. curtipes tadpoles whose parotoid glands were surgically removed, did not touch those with intact glands, suggesting a role for the parotoid gland secretion in predator deterrence. Histochemical and biochemical analyses of the gland secretion revealed the presence of high concentrations of proteins, lipids, and alkaloids. SDS-PAGE showed the presence of proteins with prominent bands at 17 and 50kDa. The presence of other small molecules (950–2000amu) as detected by LC–MS showed the presence of five major peaks. Peaks 1 and 2 are probably tetrodotoxin and/or its analogs. Peaks 3 and 5 are possibly bufalin and argininosuccinic acid, respectively while peak 4 remains unidentified. Thus, secretion of parotoid glands of larval C. curtipes contains chemicals which, either alone or in combination, might be responsible for deterring predators. [Copyright &y& Elsevier]