Aegithalidae – Tit-warblers, Bush Tits & Long-tailed Tit

The Aegithalidae (Bushtits, Tit-warblers & Long-tailed Tit), are a family of small, (mostly) drab passerine birds with moderately long tails. The family contains 11 species in three genera, all but one of which are found in Eurasia (the other is in North America). Bushtits are active birds, moving almost constantly while they forage for insects in shrubs and trees. During non-breeding season, birds live in flocks of up to 50 individuals. Several bushtit species display cooperative breeding behaviour, also called helpers at the nest. The family is part of the sylvioid radiation of oscine passerines. In the past, they have been placed with the tits and chickadees and penduline-tits within a more inclusive Paridae. However, molecular phylogenetic studies now show that Aegithalidae and Paridae are only distantly related within Sylvioidea. Aegithalidae forms a well-supported clade with Phylloscopidae and Scotocercidae. Aegithalidae is most likely sister to Scotocercidae.

All the Aegithalidae are forest birds, particularly forest edge and understory habitats. The species in the genus Aegithalos prefer deciduous or mixed deciduous forests, while the tiny Pygmy Tit is found mostly in montane coniferous forest. The Bushtit is found in a wide range of habitats, including on occasion sagebrush and other arid shrublands, but is most common in mixed woodland. Most species in this family live in mountainous habitats in and around the Himalayas, and all are distributed in Eurasia except the American Bushtit, which is native to western North America. The Long-tailed Tit has the most widespread distribution of any species of Aegithalidae, occurring across Eurasia from Britain to Japan. One species, the Pygmy Bushtit, is restricted to the mountains of western Java.

Crested Tit-warbler Leptopoecile elegans – ©Dubi Shapiro

The species in this family are generally not migratory, although the long-tailed tit is prone to dispersing in the northern edges of its range (particularly in Siberia). Many mountainous species move to lower ground during the winter.

They are omnivorous, primarily eating insects and other invertebrates such as leafhoppers, treehoppers, aphids, scale insects, and caterpillars. Plant material, such as berries or seeds, is taken occasionally during the winter. The family generally forages arboreally, usually in the shrub layer or canopy, and seldom visits the ground. Prey is generally gleaned from branches, leaves and buds. Less frequently, prey is taken in the air. While foraging, this agile family may hang upside down on branches (although this behaviour is not thought to occur in the tit-warblers) and even manipulate branches and leaves in order to locate hidden food.

White-browed Tit-warbler Leptopoecile sophiae – ©Dubi Shapiro

They live in flocks ranging from four to fifty individuals. Flocks form as soon as one breeding season finishes and last until the next one begins. Long-tailed Tits have large broods and after fledging the parents and chicks will form a flock of a dozen or more. They maintain contact with sibilant or tinkling calls; their songs are quiet. Other species of birds, such as tits or warblers, will occasionally joining the flock to forage.

The family generally has a monogamous breeding system. Pairs may be aided by helpers, where a related individual (or more than one) helps the established pair raise the young. This has been recorded in at least four of the species; further research is required to see if the behaviour carries over to other members of the family.

American Bushtit Psaltriparus minimus – ©VJAnderson, CC BY-SA 4.0 via Wikimedia Commons

Aegithalids make domed, bag-like, nests of woven cobwebs and lichen, which they line with feathers. They make the nests in trees with thick foliage, making them difficult for predators to find. The clutch generally comprises six to ten white eggs, which in many of the species have red speckles. Adults incubate the eggs for about two weeks; young stay in the nest for about sixteen or seventeen days. In at least four of the species (Long-tailed Tit, American Bushtit, Black-throated Bushtit and Silver-throated Bushtit), only the female incubates. Young chicks are fed exclusively on insects and spiders.