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New Jersey Endangered and Threatened Species Field Guide

Image of Worm-eating warbler.Zoom+ Worm-eating warbler. © Blaine Rothauser

Worm-eating warbler

Helmitheros vermivorum

Species Group: Bird

Conservation Status

State: Special Concern (Breeding)



The worm-eating warbler is a small migratory songbird about 5-5 ½ inches in length. Both the male and female are a dull olive color. The back is darker than the buff-colored belly and breast and the buff-colored head has black stripes along the eyes and on the crown. Its tail is relatively short and its bill large.

Image of Range of the worm-eating warbler in New Jersey.Zoom+ Range of the worm-eating warbler in New Jersey.


The breeding range of the worm-eating warbler extends across much of the eastern half of the US from Iowa in the northwest to New England in the northeast and as far south as the Gulf Coast. It winters in the West Indies, Central America and southeastern Mexico.

Breeding habitat includes upland deciduous forest, usually on a hillside or steep slope, with patches of understory comprised of shrubs such as mountain laurel. Winter habitat consists of undergrowth shrub and understory layers of forest.


Worm-eating warblers feed on spiders and insects, such as caterpillars. They primarily forage amongst dead leaves on the forest floor but will feed at the tree tops as trees leaf-out in spring.


The breeding season for the worm-eating warbler in New Jersey is between early-May and mid-August. Nests are built on the ground, usually on hillsides among dead leaves and tree roots, often at the base of a sapling. Nesting material consists of skeletonized and decayed leaves which may be lined with fungi, moss, fine grasses, or hair.

Between 4 to 5 eggs are laid and incubation by the female lasts about 13 days. The young are tended to by both parents and leave the nest at 10 to 11 days after hatching. There is a single brood during the breeding season.


The worm-eating warbler is sensitive to forest fragmentation and requires large tracts of mature forest with dense understory patches of shrubs. Feral cats and subsidized predators may threaten this species’ nesting success since their nest locations are highly vulnerable on the ground. It is currently listed as a Species of Special Concern in New Jersey (not yet endangered or threatened but possibly on its way).

Text written by Michael J. Davenport in 2011.

Scientific Classification

Kingdom: Animalia
    Phylum: Chordata
       Class: Aves
          Order: Passeriformes
             Family: Parulidae
                Genus: Helmitheros
                   Species: H. vermivorum

Find Related Info: Migratory songbirds, Special concern

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