I just remarked over at River Tam's place that no one would ever call me mannish. No one would ever think I'd be good at field work, either. I'm petite, just 5'1" (155 cm) with a really slight frame. Field work in my discipline relies on one crucial activity* that is most efficient when the worker has height, mass, and strength on her side. I have none of those qualities, unless you're comparing me to a child.
I hate field work, mostly because I'm just not built for it, or at least not for the key tasks. I almost always need a helper in the field. A few years ago I was engaged in a project that required frequent field efforts that I could not do alone so one of the technicians came with me. He could have done this job on his own but since it was for my PhD, it was my fieldwork and I had to be there, turning a one-person job into a two-person job. It frustrates me that I can't be more self-reliant. I also dislike the one-and-only-chance nature of field work; the conditions today will not be the same as tomorrow or next week, so if you fuck it up, you can never really redo it.
But. Field work takes more than just the brute force tasks. It takes a lot of organization, good judgment, and for some things we do, the ability to stay crouched on the ground for hours on end. I can do those things. So even though I can't do that one crucial task, I can do many of the things that go along with it that are also essential. It's hard to remind myself that I'm useful, even good, in the field without the ability to do the big strong stuff, but I am.
One of the benefits of being in a female-dominated lab is that no one connects my poor aptitude for field work with being a woman. Blame it on being small -- yes, but on being a woman -- no. Research Advisor is a machine in the field, while one of the male PIs is worthless. On the other hand, our one male technician is excellent in the field. Some of the female techs can hold their own, too. It's just not a gender thing.
I'm still last picked for field work that's not for my PhD, but that's partly because everyone knows I hate it and partly because no one is paying me to help with other lab projects (in contrast to the technicians who are paid for that). And who am I kidding, it's still partly because I'm a wimp, but whatever. I'm happy I'm not on the trip to do crappy field work this week, like many of my lab mates are.
*If you're positively dying to know what it is, send me an email.