The answer is - hypothesis.
In here we have a situation where the scientist has be observing a certain behavior of the snakes under certain conditions. So he has some basis for proposing it as new exciting discovery, but the evidence are still basic ones and further investigation is needed.
Considering the definition for what is a hypothesis - ''a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation'' - it perfectly fits the given scenario.