Pros
As a grants specialist, I love that I can support wildlife conservation using my use my skills with numbers and operations. My experience has been if you're good at your job, others will notice and will go out of their way to help you lateral into a position with another program if you're interested.
Cons
Conservation is, still, overwhelmingly dominated by white men, so it can be hard to have your voice heard if you're literally anything else. Like all government agencies, USFWS is reactive instead of proactive, so it can be frustrating for anyone who's got a vision of their own. Also, again, like all government, you can only be promoted so far before you end up in management, so there are a lot of technically competent people who have no idea how to manage who are in management positions, which can be another source of frustration. There's a fair bit of incompetency and micromanagement from those positions; good managers are rare.