Cohabitating different species

[Roman]

That's fascinating! And you're braver than me, the sources I've seen say these snakes will eat most anything, including frogs. Though if yours is well-fed & the
frogs are pretty small, they might not be worth bothering with? That's cool that the frogs eat bugs off the snake too, lol...

What sources are these? Most of what I could find stated that adult Spilotes pullatus would mainly feed on small mammals and occasionally on nestling birds or eggs, I found no reliable source pointing out that they would feed on frogs or other reptiles. Sure there are some “care sheets” telling you that they will feed on everything they can get (usually the same care sheets describing them as always aggressive biting machines from authors who have most likely never seen any Spilotes close and personally). My best source for deciding on food composition is this paper:

“Otavio A. V. Marques, Diego F. Muniz-Da-Silva, Fausto E. Barbo, Silvia R. Travaglia Cardoso, Danusa C. Maia, and Selma M. Almeida-Santos: Ecology of the Colubrid Snake Spilotes pullatus from the Atlantic Forest of Southeastern Brazil, Herpetologica, 70(4):407-416. 2014”

Your point of size differences is one I considered myself as well, it makes no sense for my big male (2.5 m / 8 ft, 3.5 kg) to hunt for a tiny frog, he would waste maybe twice the energy to swallow it as he would gain from digesting it.

However my main reasoning was (still is) that my snakes are WC from French Guiana. It was absolutely clear that I would only try this with a frog species which can be also found in French Guiana, that was one of the main reasons why I took Dendrobates tinctorius, this frog can be found all over there. The snakes should “know” that it is extremely unwise to eat a frog with this color scheme, otherwise this warning coloration would not make any sense. I am not sure if this would have worked with other dart frogs from somewhere else, like southern Brazil, which are not found in Guiana. I didn’t want to find out if the warning coloration is “general” enough to be recognized even if the locality of snake and frog is thousand miles apart from each other.

I am also not sure if it would work with sub adult Spilotes, for a 100 to 120 cm (3 to 4 ft) long snake a dart frog would be just the right size for dinner and we know next to nothing about feeding behavior of young Spilotes in the wild, so I will do this cohabitation only with adult snakes.