These are (probably) two different male Willow Flycatchers in two adjacent territories from two successive years at a local grassland preserve. Most of the Willow Flycatchers I encounter are not very friendly, but sometimes you find an especially hormonal one that is perhaps still looking for a mate. The one from 2009 kept shuttling between bush tops proclaiming territory and eventually briefly stopped in a position when I could take a photo. The one from 2010 was a much more assertive bird - in fact at one point I wasn't sure that it wasn't singing at me - and it may or may not be associated with it being in more marginal territory with less cover. The 2010 male has fewer perches and is considerably less shy in singing from them. It's almost certainly unpaired, although I don't monitor breeding success in this location. There are at least two other Willow Flycatcher territories in this general area, and they are by no means a rare bird in the right habitat in NJ.
