The sittellas are a family Neosittidae of small passerine birds found only in Australasia. They resemble nuthatches, but whilst they were considered to be in that family for many years they are now afforded their own family. They do not migrate other than for local movements.

The sittellas are small woodland birds with thin pointed down-curved bills, which they use to extricate insects from bark. Nests are open cups in forked branches.

They were formerly classified in two separate genera with the black sittella in Daphoenositta and the varied and Papuan sittellas in Neositta. The two genera are now usually merged, with Daphoenositta having priority.

Evolution and taxonomy

The true evolutionary affinities of the sittellas have long been clouded by their close resemblance to the Northern Hemisphere nuthatches. As late as 1967 the sittellas were retained in that family by some authorities, although doubts about that placement had been voiced in the previous decades. Both their climbing technique and overall morphology are extremely similar; however they differ both in their sociality and their nesting behaviour, as sittellas create nests on branches whereas nuthatches nest in cavities in trees. In addition the specifics of the morphology of the leg differed, with sittellas having leg muscles more similar to those of the honeyeaters. Their placement was then moved to various families, including the Old World babblers (an infamous wastebasket taxon), the true treecreepers (Certhiidae, which range across the Holarctic and Africa) and the Australian treecreepers (Climacteridae). Their relationship with the Australian radiation of passerines was suggested by S. A. Parker on the basis of egg colour, nest structure and nestling plumage, and their position in this radiation was vindicated by Sibley and Ahlquist's DNA–DNA hybridization studies. These researchers placed the sittellas in a monotypic tribe within the superfamily Corvoidea. Today they are afforded their own family in a clade close to the berrypeckers and longbills (Melanocharitidae) and the whistlers (Pachycephalidae).

The sittellas comprise a single genus Daphoenositta, which contains three species. The three species were once considered to belong to two genera, but when the two genera were merged, the genus name of the less well known black sittella was adopted due to priority (1897, versus 1901 for Neositta), while the family retained the family name based on the junior synonym Neositta. The most common species, the varied sittella, was once thought to represent five separate species in Australia, but in spite of considerable variation in plumage there are extensive zones of hybridisation where the forms overlap (including an area of Queensland where all five Australian subspecies exist), and are now thought to be a single species with five subspecies. The black sittella is monotypic, while the Papuan sitella has four subspecies.

Daphoenositta trevorworthyi is a fossil sittella species from the middle Miocene, representing the oldest known fossil record of the sittella family. The species was described from a distal tibiotarsus discovered in the Riversleigh World Heritage Area in northwestern Queensland, Australia.

Species

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! Image !! Common name !! Scientific name !! Distribution

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|120px ||Black sittella||Daphoenositta miranda||New Guinea

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|120px ||Varied sittella||Daphoenositta chrysoptera|| Australia

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|120px ||Papuan sittella||Daphoenositta papuensis|| New Guinea

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Morphology

thumb|The bill of the [[varied sittella is upturned. ]]

The three species of sittella are small passerines which resemble the unrelated nuthatches in appearance. Amongst Australian birds varied sittellas are usually the first to arrive at roost sites in the evening and the last to leave in the morning, although they are not necessarily the first to sleep or last to wake. At the roost site the position occupied along the branch is generally not random; instead males generally adopt positions at the edges of the group whilst young birds tend to be found in the centre.

Diet and foraging

The principal component of the diet of sittellas are insects and other arthropods. Sticks were used to pry boring beetle larvae out of cavities, in a similar fashion to that of tool using woodpecker finches of the Galápagos Islands.

Breeding

Very little is known about the breeding of either of the two species of sittella in New Guinea, although black sittellas in breeding condition have been observed August and May, suggesting that they may either be biannual breeders or year round breeders. The varied sittella populations in Australia are cooperative breeders (and the group composition of black sittellas suggest they are too), Whilst incubating the breeding female is fed by the breeding male and helpers. After hatching the female broods the young for a few days, and for up to two weeks at night. The chicks are fed for 19–20 days in the nest. After fledging the chicks have a protracted period of parental care lasting up to 80 days, although 60 days is more usual.

References

  • Sittella videos on the Internet Bird Collection