Keeping a record of the global decline of amphibian populations depends on the identification and marking of individuals in the field, commonly by toe-clipping. This work is under threat: the Brazilian federal government and non-governmental organizations want to prohibit toe-clipping without scientific justification.

Toe-clipping is a simple, cost-effective, minimally invasive marking technique that has been in use for decades in herpetological research. The Brazilian federal agency that enforces environmental policies, IBAMA, is claiming that the practice is a form of mutilation and should be a criminal offence under federal law (see go.nature.com/qkij7l; in Portuguese). The Brazilian Herpetological Society has protested against this anthropocentric position (see go.nature.com/thpwdg; in Portuguese) on the grounds that it would set back efforts to understand amphibian decline.

Brazil is home to the greatest amphibian diversity on Earth, but knowledge of population dynamics is scant and will remain so without access to reliable marking methods. We acknowledge that toe-clipping is not an ideal solution but, when properly implemented, it has minimal effects on amphibian survival and behaviour. Without this technique, it will be harder to obtain crucial information that could prevent amphibian species from becoming extinct (W. C. Funk et al. Nature 433, 193; 2005).