The robins are small passerine

Passerine

A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...

 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 comprising the genus Erithacus. They were formerly classed as members of the thrush

Thrush (bird)

The thrushes, family Turdidae, are a group of passerine birds that occur worldwide.-Characteristics:Thrushes are plump, soft-plumaged, small to medium-sized birds, inhabiting wooded areas, and often feed on the ground or eat small fruit. The smallest thrush may be the Forest Rock-thrush, at and...

 family, but now considered to be Old World flycatcher

Old World flycatcher

The Old World flycatcher family Muscicapidae is a large family of small passerine birds mostly restricted to the Old World. These are mainly small arboreal insectivores, many of which, as the name implies, take their prey on the wing.-Characteristics:...

s of the chat

Chat (bird)

Chats are a group of small Old World insectivorous birds formerly classed as members of the thrush family Turdidae, but now considered Old World flycatchers....

 subfamily (Saxicolinae).

The vernacular name "robin" is also applied to some other chats, as well as certain thrushes and some unrelated songbirds; see Robin#Birds.

The three or four species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 presently placed here are:

• European Robin
  European Robin
  The European Robin , most commonly known in Anglophone Europe simply as the Robin, is a small insectivorous passerine bird that was formerly classed as a member of the thrush family , but is now considered to be an Old World flycatcher...
  
  , Erithacus rubecula
  • Tenerife Robin, Erithacus (rubecula) superbus
• Japanese Robin
  Japanese Robin
  The Japanese Robin or komadori is a songbird. Recent research suggests that the East Asian robins belong into a new genus uniting them with some East Asian Luscinias such as the Siberian Blue Robin.The name "Japanese Robin" is also sometimes used for the Red-billed Leiothrix .The specific name...
  
  , Erithacus akahige
• Ryūkyū Robin
  Ryukyu Robin
  The Ryukyu Robin is a bird endemic to the Ryūkyū Islands, of Japan. It is sometimes placed in the genus Luscinia, but recent research suggests that the East Asian robins belong into a new genus uniting them with some East Asian Luscinias such as the Siberian Blue Robin.The specific name komadori...
  
  , Erithacus komadori

The two Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

n species were formerly considered to be members of the genus Luscinia

Luscinia

Luscinia is a genus of smallish passerine birds, containing the nightingales and relatives. Formerly classed as members of the thrush family Turdidae, they are now considered to be Old World flycatchers of the chat subfamily...

; apparently, both genera need to be split and rearranged. The European species would then be the only remaining Erithacus, whereas the East Asian species are closely related to some species from the region now classed as Luscinia, for example the Siberian Blue Robin

Siberian Blue Robin

The Siberian Blue Robin, Luscinia cyane, is a small passerine bird that was formerly classed as a member of the thrush family Turdidae, but is now more generally considered to be an Old World flycatcher, family Muscicapidae. It, and similar small European species, are often called chats...

 (Luscinia cyane) and would form a new genus.

These species are stocky small birds with an upright stance and short frequently cocked tail. They have a plain brown back, and a red or black face and breast contrasting with whitish or grey underparts. The females of the Asian species are much duller than the males, but in the European Robin differences between the sexes are minimal and restricted to the shape of the boundary between the red and brown plumage on the forehead.

Erithacus robins are territorial woodland birds which build a neat cup nest in a hole or on the ground, and have a life expectancy of just over a year. They watch for 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, worm

Worm

The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...

s and other invertebrates from a low perch, and feed mostly on the ground, hopping on strong legs with frequent stops.