Oporornis is a small genus of New World warbler

New World warbler

The New World warblers or wood-warblers are a group of small, often colorful, passerine birds restricted to the New World. They are not related to the Old World warblers or the Australian warblers....

s which breed in North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. They are migratory

Bird migration

Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

, wintering south of their breeding ranges in Central

Central America

Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

 or South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

.

The four species are:

• Kentucky Warbler
  Kentucky Warbler
  The Kentucky Warbler, Oporornis formosus, is a small species of New World warbler. The Kentucky Warbler, like all members of the genus Oporornis, is a sluggish and heavy warbler with a short tail, preferring to spend most of its time on or near the ground, except when singing.Adult Kentucky...
  
  , Oporornis formosus
• Connecticut Warbler
  Connecticut Warbler
  The Connecticut Warbler Oporornis agilis is a small songbird of the New World warbler family.These 15 cm long birds have light yellow underparts and olive upperparts; they have a light eye ring, pink legs, a long tail, pale wing bars and a thin pointed bill...
  
  , Oporornis agilis
• Mourning Warbler
  Mourning Warbler
  The Mourning Warbler, Oporornis philadelphia, is a small songbird of the New World warbler family.These 13 cm long birds have yellow underparts, olive-green upperparts and pink legs. Adult males have a grey hood and a black patch on the throat and breast...
  
  , Oporornis philadelphia
• MacGillivray's Warbler
  MacGillivray's Warbler
  The MacGillivray's Warbler, Oporornis tolmiei, is a small species of New World warbler. Like all members of the genus Oporornis, these birds are sluggish and heavy warblers with short tails, preferring to spend most of their time on, or near the ground, except when singing.The MacGillivray's...
  
  , Oporornis tolmiei

Oporornis warblers are robust stocky bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s, 13–15 cm long. They have yellow underparts, olive green upperparts and generally browner wings. The head and breast are grey in the males of three species, with the females’ hood being browner and duller. However, the Kentucky Warbler looks more like a yellowthroat

Yellowthroat

The yellowthroats are New World warblers in the genus Geothlypis. Most members of the group have localised ranges in Mexico and Central America, but the Masked Yellowthroat has an extensive South American distribution, and Common Yellowthroat, the only migratory species in the group, breeds over...

, with the entire underparts yellow, and black head markings in the male plumage. This species may be a link between Oporornis warblers and the yellowthroats.

The breeding habitat is broadleaved woodlands, often in wet areas and with dense undergrowth. These skulking, fairly terrestrial warblers nest low in a bush or on the ground, laying 3-6 eggs in a cup nest.

Oporornis warblers feed on insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s and spider

Spider

Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...

s often caught on the ground or low in vegetation; they have simple churring songs and buzzing calls.

Taxonomy

Recent genetic research has suggested that only the type species

Type species

In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

 of Oporornis (Connecticut Warbler O. agilis, which is also the most distinctive member of the genus) should be retained in Oporornis, with the other three more closely related to, and better placed in, the genus Geothlypis. This change has been accepted by the AOU

American Ornithologists' Union

The American Ornithologists' Union is an ornithological organization in the USA. Unlike the National Audubon Society, its members are primarily professional ornithologists rather than amateur birders...

, but has not yet been taken up by the IOC

International Ornithological Congress

The International Ornithological Congress series forms the oldest and largest international series of meetings of ornithologists. It is organised by the International Ornithological Committee, a group of about 200 ornithologists...

.