Birds in the vineyard

The vineyard out behind our house is full of wildlife. We see rabbits, deer, and the occasional fox. There are also rodents and insects galore, and these attract the hunting birds. We will often see hawks circling above the fields looking for prey. We see pheasants and partridges in the fall and hear the spring cuckoos when they arrive in March. Crows like to sit on the vine posts in the morning, like the one below.

My zoom lens isn't good enough to get a real detailed close-up.

Recently, a mating pair of col-verts (mallard ducks) has been hanging out in the little pond outside our back gate. We also see herons in there from time to time. A few days ago, I saw this unusually bright yellow bird (below) among the vines. I've tried to identify it with my bird books, but I'm having trouble finding a close match. It looks like it might be some variety of finch, given its body size and shape.

Not the best shot; the bird would only let me get so close before flitting off to another post.

We see finches all the time around the house and garden. Chaffinches and goldfinches mostly. I don't remember seeing a bird like this one around the house. Maybe it's the breeding color of a more familiar bird? Any help from you birders out there would be appreciated.