Or, AKICILJ FTW. It seems my commenters were indeed correct: looks like she's a guinea hen all right:

This morning on my rush to the train, I spotted her in the alley behind the Mexican grocery, hanging out with a couple of crows. When she spotted me she turned and ran right up to me, cheeping a funny little cry. She's not hand tame -- she wouldn't let me get closer than her chosen proximity, but she seemed eager for company. She kept making little cries. I looked around and didn't see signs of any other guinea fowl -- she seems to be a one-off. If she's someone's free range fowl I would expect there to be others about. (Apparently Guinea fowl are good for organic gardeners -- if allowed to free range they eat mostly insects. Why yes, I did go looking for more info, once I got to work.)
In my usual, stupidly soft-hearted way, I'm worried for her -- between trying to hang out with crows, and ducks, and now me, I think she's lonely. I worried that she might be hungry as well, but from what I read it sounds like she can get by on foraging in the grass around the creek for seeds and bugs, and whatever is leftover when people feed the ducks that hang out on the creek. But still, a social bird without a flock. It seems sad.

This morning on my rush to the train, I spotted her in the alley behind the Mexican grocery, hanging out with a couple of crows. When she spotted me she turned and ran right up to me, cheeping a funny little cry. She's not hand tame -- she wouldn't let me get closer than her chosen proximity, but she seemed eager for company. She kept making little cries. I looked around and didn't see signs of any other guinea fowl -- she seems to be a one-off. If she's someone's free range fowl I would expect there to be others about. (Apparently Guinea fowl are good for organic gardeners -- if allowed to free range they eat mostly insects. Why yes, I did go looking for more info, once I got to work.)
In my usual, stupidly soft-hearted way, I'm worried for her -- between trying to hang out with crows, and ducks, and now me, I think she's lonely. I worried that she might be hungry as well, but from what I read it sounds like she can get by on foraging in the grass around the creek for seeds and bugs, and whatever is leftover when people feed the ducks that hang out on the creek. But still, a social bird without a flock. It seems sad.