Canada Warbler

At my bird walk in New York City's Central Park we spent some time at the side of a small lake and a yellowish bird was flitting around in two trees on the side of the lake. There were five or six of us trying to take photos of the bird and I asked one what kind of bird it was and he said, a "Canada," which meant nothing to me. After lots of photos one of them asked me if I'd gotten any good photos and I replied that I had "no idea," but with all the photos I'd taken I hoped one or two would be decent. 

The bird was a Canada warbler, another bird I'd never heard of. It summers in portions of Canada and the northeastern U.S. and winters in northern South America. 

Canada warbler range from Wikipedia. 

One observation, now that I've looked up a number of these warblers, is that the warblers I saw were much skinnier than the ones I'm seeing in photos. I'm assuming that the ones I was seeing were on the tail-end of a long migration from South America to the U.S. and that their time in their summer range would fatten them up. 

The chest, throat and belly is yellow and it has a dark gray back. It has a black necklace which has wiggly strands, a yellow line in front of its eyes and white eyerings. Females are not as bright and have a shorter tail.