I am interested to hear about the concern of adult amphibian marking by elastomers (visible implant elastomer). I have seen an article that concludes that this technique is reliable, and others that conclude otherwise (e.g. "VIE tags, as individuals were correctly identified only 18.4% of the time" Brannelly et al. 2014).
Has anyone used them in thick skinned species, such as those of the genus Rhinella?
I've already tried to tag Rhinella icterica with Fluorescent VI Alpha Tags, and the thick skin really makes it very difficult to identify the tag.
I inserted the tag in the lower region of individual’s leg.
Maybe the VIE tags are more visible, but I have never tried it.
I've tried tagging dark-skinned salamanders with VIE, which causes the same problem as thick skinned anuran species.
One of the solutions I found was to inject the elastomer on the ventral side, at the basis of the limbs. The skin is thinner there, which makes it easier to see the tag.
Another solution I used was to inject the VIE in the palm of the hands and feet. As with the ventral side, the skin is usually thinner there, which makes tags more visible.
With Rhinella, fingers are probably long enough to even allow coding schemes using finger locations, as described in this paper :
https://ufwildlife.ifas.ufl.edu/pdfs/hoffmann_etal_2008.pdf
( Technology meets tradition: A combined VIE-C technique for individually marking anurans, Hoffman et al, 2008)
Here, they use a combination of clipped toes and VIE tagging, a double-tag system enabling to identify animals even if one of the tags has failed (it is unlikely that both fail at the same time). Hope you'll find this paper useful !
Good luck with your research,
Benjamin
I second Benjamin's comment. I've also used VIE on Anaxyrus canorus by inserting it just under the thinnest layer of skin on the ventral side of the abdomen and between the toes on Anaxyrus baxteri. It was highly visible in those areas even after several weeks.