Please explain what you mean by "do your own other research". Searching with Google or scanning social media posts by people you agree with is not research. Someone with no education in the field isn't qualified to do research.
The same people probably are not qualified to call her a quack either.
Well then you'll just have to believe Crockford, who has written many books and research papers about polar bears, and who has also been interviewed in the media as a polar bear expert many times.
I haven't taken a position either way. Media interviews would not count with me. Research papers that survived peer review and were published would count.
Climate academics are on record as saying they manipulate peer review to reject valid science if it would weaken their "message", so that's not a good idea.