1 Crow, turtle, dog, or snake come to mind.  Snake is least likely, since MomGoose would probably beat the crap out it.

When I was a child, we had a hen that only saved two of her chicks from some threat that took the other chicks one night.  We deduced that when the hen jumped up to run away from where they were sleeping, she had clamped her wings to her sides an managed to carry a couple of chicks with her.

You'd be surprised what a turtle can pull under.

2

I've seen raccoons around here, and that's my bet.

A couple of days ago one of the neighborhood cats was looking very interested, but one of the adult geese chased it away. I doubt the cat was responsible.

As far as snakes go, the only ones we have around here are garter snakes, so far as I know, and for them grasshoppers are more their speed.

There are no rattlesnakes on this side of the Cascades.

3 I grew up in Tennessee and the chicken-eating snakes around there were the so-called chicken snakes.    (From a quick Google search and looking at the images, I'd say they were black rat snakes.  You guys in the west don't appear to have them.)

We pulled one out of our barn that was around 6 feet long.  That particular snake had attempted to eat a hen that had made a nest near where that snake was living between the stalls (which is why we were looking for it).  It hadn't been able to dis-articulate its jaws enough to swallow the hen, but it managed to open its mouth sufficiently to make it up to where the wing connects to the breast (going headfirst, of course).

I've seen a crow snatch a baby rabbit from the ground, so I'd think that a gosling would be small enough to nab.

4

I don't think we have any snake that big here in the Willamette valley.

There are crows around here, but they're thoroughly cowed by the ducks and geese. Sometimes when I toss bread out, the ducks and geese come in readily and start gobbling it. Crows sometimes fly down and land, but they stay outside the area where my bread is. They won't come in and compete directly; they hope to dance in and seize a piece and then fly away. Sometimes they do; mostly they don't. The crows act like they're afraid of the ducks, not to mention the geese.

I can't see any of them trying to do that with a gosling, given how afraid they seem to be of the geese.

My vote is for something furry. There are opossums all over the place around here, and I mentioned that I've seen a raccoon. I wouldn't be surprised if there were skunks around here, too.

And at least once I've seen a coyote here in the yard. (The poor thing was badly hurt, probably hit by a car.)

5 I've seen eagles, skunks, and racoons in plenty just a couple miles south of you.  Just the other week I saw a pair of coyotes hanging out near the Fanno creek trail, which goes through your area.  A few years back we had multiple sightings of a mountain lion (or maybe it was a bobcat) in my neighborhood.  Any of those critters would happily make a meal of a gosling.  And of course I'm sure there are plenty of cats or stray dogs that would happily snatch a gosling if the parents let it stray far enough away.