Not directly mentioning frogs but this [0] paper offers more details on the particular toxin type (Batrachotoxin), which in turn. is present in bettles, birds a

Not directly mentioning frogs but this [0] paper offers more details on the particular toxin type (Batrachotoxin), which in turn. is present in bettles, birds and frogs [1]. Also, check this argument suggesting they evolved (frogs and birds) the compound in parallel. [2] > Homobatrachotoxin is a member of a class of compounds collectively called batrachotoxins that were previously considered to be restricted to neotropical poison-dart frogs of the genus Phyllobates. The occurrence of homobatrachotoxin in pitohuis suggests that birds and frogs independently evolved this class of alkaloids. [0] Dumbacher, J. P., & Fleischer, R. C. (2001). Phylogenetic evidence for colour pattern convergence in toxic pitohuis: Mullerian mimicry in birds? Proceedings of the Royal Society B: Biological Sciences, 268(1480), 1971–1976. doi:10.1098/rspb.2001.1717 [1] https://en.wikipedia.org/wiki/Batrachotoxin https://en.wikipedia.org/wiki/Batrachotoxin [2] Dumbacher, J., Beehler, B., Spande, T., Garraffo, H., & Daly, J. (1992). Homobatrachotoxin in the genus Pitohui: chemical defense in birds? Science, 258(5083), 799–801. doi:10.1126/science.1439786