Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: The brown tree snake is a nonnative species found on the South Pacific island of Guam. The brown tree snake population in Guam is so large that it negatively affects the humans there. Which statement best explains why the brown tree snake has flourished in Guam?
There are no natural snake predators.
Lack of natural predators.