[Flylady]

I always find this an interesting discussion. My perspective is based on the fact that I have lived in Southern California for over 45 years in a region where they live in sort of a land locked area. During the past 10 years there has been a concerted effort to save what is left of the population. Many have a tracking collar so their activity is monitored. When food sources become limited they will go after farm stock or pets on the fringe of developed areas. Unfortunately the only ones most of us have seen are the dead ones from being hit by a car or dieing from rat poisoning.
Living in NH and the vast amount of wilderness I can see why it is nearly impossible to verify if they are here. They have plenty of wildlife to sustain themselves and being so elusive by nature, there is very little reason for them to go into populated areas. Definitely the best way for verification is the use of trail cams.