The Conserve Wildlife Foundation website has an online New Jersey Endangered and Threatened Species Field Guide which has excellent information about New Jersey's endangered and threatened species.
A pretty example is the Golden-winged warbler, Vermivora chrysoptera, whose breeding population is endangered.
"In New Jersey, golden-winged warblers may be observed as a migrant throughout the entire state. It has only been documented to breed within the northwestern portion of the state.
Golden-winged warblers breed in wet scrub/shrub habitat, marshes, and bogs on the edge of woodlands, usually within early successional habitat only. They prefer openings within deciduous woodland with thick undergrowth. They can often be found within areas bordering woodland and marsh which have been cut for utility right-of-ways, such as powerlines.
Like many wood warblers, golden-winged warblers are insectivorous. They glean small insects from twigs and leaves."