If I were the biologist, I would not write the letter .. probably not at all, but certainly not that way. Biologists are bottom of the totem pole, necessary experts and resources/advisors, but not the policy makers. That biologist has no obligation to acknowledge receipt of your request nor any obligation to address your questions. First thing I would NOT do is answer the question without consulting with someone with sufficient authority within the department to officially speak for the department. (And such a person will probably kick it up from district to state level rather than go out on a limb themselves.) The response, if there is one at all, would read something to the effect of "existence or non-existence of primates in North America falls outside of my professional training and is outside my authority to give comment on. Have a nice day."
You are not going to get an honest, straight forward answer from anyone unless they have been authorized to do so by their superiors. That is likely going to have to go clear to the top of whatever agency they work for. Unless they have decided it is time to break the story, you're going to get "no comment" in one form or another. If you've worked at all with state or federal agencies, you know it is foolish to think otherwise. If you have not worked with state or federal agencies, you simply are ignorant of the basic survival rules of bureaucracy.
MIB