This is a female Northern Parula photographed in May 2002. Parulas are fairly numerous migrants in the park but are often overlooked since they feed high in the tree-tops... Fig. 1, also from Central Park, shows a female Parula in fall colors.
Fig. 2 is a Nashville Warbler, also from May 2002. (Hint: if it has a *complete* eye ring it cannot be a Parula - Parulas have top and bottom eye arcs but they do not meet.) The Nashville Warbler is a fairly common visitor to Central Park, unlike Fig. 3, a Tennessee Warbler, which is very uncommon.
All these birds are likely to be sighted around this time of year. The Tennessee has so far been elusive perhaps next week.