I know sentience is an abused word, but for almost any of its practical definitions that's a false statement.
Sentience is the ability for subjective experience, which applies to any of the animals being discussed here. If you're thinking of something like self-awareness (a totally separate quality), you're probably correct. But that has nothing to do with the ability to learn.
Those actions can still be done unintentionally. For example, a particular kind of snake can prefer to eat some particular kind of fruit when they are young, which also happens to be the favourite plant for a cane toad to rub on to get rid of itchy bottoms.
Pretty cool link on the Colorado River toad. Apparently raccoons use the same strategy as these crows, turning the toad over on its back and eating the belly.
You get a addictive behaviour and slowly immunize yourself with microdoses of poison.
You hunt your prey in a poison diluting or neutralizing environment.
You set the plains on fire with dryd grass to interrupt the feeding cycle of the plague and eat the denatured poisonous creatures.
There are a lot of different strategies. One must admire the crows for eating the fugu though.