That doesn't prove they are not here.
Of course it doesn't. Proving a negative is nearly impossible and foolish to waste time trying. Bad logic to infer something exists because of a lack of evidence to show it doesn't. What is of note here is that all the possibilites to produce even a shred of evidenceto support their existencehave failed completely. It is therefore only logical to be skeptical. As far as I'm concerned it doesn't matter how many cousins uncles friends of the family who goes to church every sunday claims he saw one for sure, I'm simply not going to believe the stories. Until a reputable source confirms
positive evidence of their existence I'm in the nay category.
BTW, the official NYDEC position on this is not that they don't exist here but rather that there is no evidence to support the claim.