The Tetrakas and allies are a newly validated family of

songbird A songbird is a bird belonging to the suborder Passeri of the perching birds (Passeriformes). Another name that is sometimes seen as the scientific or vernacular name is Oscines, from Latin ''oscen'', "songbird". The Passeriformes contains 500 ...

s. They were formally named Bernieridae in 2010. The family currently consists of eleven

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

(in eight

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

) of small forest birds. These birds are all

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

. In 1934, the

monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic grou ...

of this group was proposed by

Finn Salomonsen Finn Salomonsen (31 January 1909 – 23 April 1983) was a Danish ornithologist. He is best known for his work on the birds of Greenland. His interest in Greenland began at the age of 16 when he made a trip with Lehn Schioler to the Upernavik Dis ...

but the traditional assignments of these birds were maintained, mistaken by their

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

and the lack of dedicated research. The families to which the Malagasy warblers were formerly assigned—Pycnonotidae (

bulbul The bulbuls are members of a family, Pycnonotidae, of medium-sized passerine songbirds, which also includes greenbuls, brownbuls, leafloves, and bristlebills. The family is distributed across most of Africa and into the Middle East, tropical As ...

s) and even more so Timaliidae (

Old World babbler The Old World babblers or Timaliidae are a family of mostly Old World passerine birds. They are rather diverse in size and coloration, but are characterised by soft fluffy plumage. These are birds of tropical areas, with the greatest variety in S ...

s) and the

Old World warbler Old World warblers are a large group of birds formerly grouped together in the bird family Sylviidae. The family held over 400 species in over 70 genera, and were the source of much taxonomic confusion. Two families were split out initially, the ci ...

—were used as " wastebin taxa", uniting unrelated lineages that were somewhat similar

ecological Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

ly and morphologically. It was not until the analysis of

mtDNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial DNA ...

cytochrome ''b'' and

16S rRNA 16S rRNA may refer to: * 16S ribosomal RNA 16 S ribosomal RNA (or 16 S rRNA) is the RNA component of the 30S subunit of a prokaryotic ribosome ( SSU rRNA). It binds to the Shine-Dalgarno sequence and provides most of the SSU structure. The g ...

as well as

nDNA Nuclear DNA (nDNA), or nuclear deoxyribonucleic acid, is the DNA contained within each cell nucleus of a eukaryotic organism. It encodes for the majority of the genome in eukaryotes, with mitochondrial DNA and plastid DNA coding for the rest. I ...

RAG-1 The recombination-activating genes (RAGs) encode parts of a protein complex that plays important roles in the rearrangement and recombination of the genes encoding immunoglobulin and T cell receptor molecules. There are two recombination-activ ...

and

RAG-2 The recombination-activating genes (RAGs) encode parts of a protein complex that plays important roles in the rearrangement and recombination of the genes encoding immunoglobulin and T cell receptor molecules. There are two recombination-activ ...

exon An exon is any part of a gene that will form a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term ''exon'' refers to both the DNA sequence within a gene and to the corresponding sequen ...

sequence In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of elements (possibly infinite) is calle ...

data, that the long-proposed grouping was accepted.

Taxonomy and systematics

The family contains 11 species divided into 8 genera. Several of these species are very poorly known and were described by science only very recently.

Appert's tetraka Appert's tetraka formerly known as Appert's greenbul (''Xanthomixis apperti'') is a small passerine bird endemic to the south-west of Madagascar. The species was only described in 1972, and has been the subject of considerable taxonomic confusion ...

was only described in 1972 and the cryptic warbler in 1996. The Appert's tetraka, along with the

dusky tetraka The dusky tetraka (''Xanthomixis tenebrosa'') is a species of Old World warbler in the family Bernieridae. It is found only in Madagascar. Its natural habitat is subtropical or tropical moist lowland forests. It is threatened by habitat loss. ...

are threatened by habitat loss, and are listed as vulnerable. Most members of this family live in the humid

rainforest Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainfores ...

s in the east of

, though a few species are found in the drier southwest of the island. They feed on

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

s and will form

mixed-species feeding flock A mixed-species feeding flock, also termed a mixed-species foraging flock, mixed hunting party or informally bird wave, is a flock of usually insectivorous birds of different species that join each other and move together while foraging. These ar ...

s of up to six species while foraging.

Taxonomy and systematics

References

Further reading