Hahaha! Yeah, maybe after 35 years in the service you'd make $75,000. I don't even make $30K, and I've been a GS-0404 (that's a Biology Science Tech) for 2 years. I'm now at a pay grade of 05. And keep in mind that most biology positions are temporary and seasonal, so you'll be LUCKY to work 6 months out of the year, if you can find a job for that season. Most permanent, year round jobs start at a GS pay grade 07 (you qualify for that with 3-4 years of experience in that specialized area, or a Masters/Ph.D.).
And there's NEVER a job where you want there to be a job, so you end up travelling all over the US (I've been to West Virginia, Wisconsin, Northern Michigan, Utah, and Canada) working. That means no permanent house, no critters (you can't move them all over the place, can you? Better find a good herp sitter that doesn't mind watching them for 6 months out of the year), new faces, new places. It's not glamorous. Everything I have with me is what I can fit in my car. It's rewarding, it's interesting, it's fun seeing new places, and I wouldn't trade my job for anything, but it's HARD. Mentally, physically, and emotionally. It's hard not having a 'home'.
To be a Wildlife Biologist, you'll probably need a Master's degree. I've worked BST jobs for 2 years now, and I still don't qualify for most Wildlife Biologist positions. $30-75K might be how much an average biologist makes (one that's been in the service for 10, 20 years), but it's not how much every biologist makes, and not how much you will make starting out. And trust me, $30K is NOT as much as it sounds. Really.
I told you once, and I'll tell you again: if you're looking to get rich, you're in the wrong field.
Don't pick a job based on how much money you're going to make. Choose it based on how happy you are going to be. If you hate your job, it doesn't matter if you make $175,000; You'll be miserable.