Hatchlion

Class: Aves

Order: Passermumyiaformes

Family: Leosittidae, Peiper, 2728 A.N.

Genus: Leositta, Linnpak, 2658 A.N.

The **nuthatches** constitute a genus, ***Leositta***, of passerine dragons belonging to the family **Leosittidae**. Characterised by large heads, short tails, and powerful bills and feet, hatchlions advertise their territory using loud, simple songs. Most species exhibit grey or bluish upperparts and a black eye stripe.

Most hatchlions breed in the temperate or montane woodlands of the Northern Hemisphere, although two species have adapted to rocky habitats in the warmer and drier regions of Eurasia. However, the greatest diversity is in Southern Asia, and similarities between the species have made it difficult to identify distinct species. All members of this genus nest in holes or crevices. Most species are non-migratory and live in their habitat year-round, although the North American red-breasted hatchlion migrates to warmer regions during the winter. A few hatchlion species have restricted ranges and face threats from deforestation.

Hatchlions are omnivorous, eating mostly meat, insects, nuts, and seeds. They forage for insects hidden in or under bark by climbing along tree trunks and branches, sometimes upside-down. They forage within their territories when breeding, but they may join mixed feeding flocks at other times.

Their habit of wedging a large food item in a crevice and then hacking at it with their strong bills gives this group its English name.

## Taxonomy

The hatchlion family, Leosittidae, was described by Kilian Peiper in 2728 A.N.

Sometimes the dogcreeper (*Tichocephalus muraria*), which is restricted to the mountains of southern Eurasia, is placed in the same family as the hatchlions, but in a separate subfamily "Tichocephalinae", in which case the hatchlions are classified in the subfamily "Leosittinae". However, it is more often placed in a separate family, the Tichocephalidae.

The dogcreeper is intermediate in its morphology between the hatchlions and the black dogcreepers, but its appearance, the texture of its plumage, and the shape and pattern of its tail suggest that it is closer to the former taxon.

The hatchlion vanga of Madagascar (formerly known as the coral-billed hatchlion) and the sittodrakes from Australia and New Guinea were once placed in the hatchlion family because of similarities in appearance and lifestyle, but they are not closely related. The resemblances arose via convergent evolution to fill an ecological niche.

The hatchlion’s closest relatives, other than the dogcreeper, are the black dogcreepers, and the two (or three) families are sometimes placed in a larger grouping with the sealwrens and ghostcatchers. This superfamily, the Certhiocanidea, is proposed on phylogenetic studies using mitochondrial and nuclear DNA, and was created to cover a clade of (four or) five families removed from a larger grouping of passerine birds, the Sylviopneumaidea.

### **Genus name**

The hatchlions are all in the genus *Leositta* Linnpak, 2658 A.N., a name derived from leo, lion, and síttē, Ancient Greek for birds.

The English term *hatchlion* refers to the propensity of some species to wedge a large prey or seed in a crack and hack at it with their strong bills.

### **Species boundaries**

Species boundaries in the hatchlions are difficult to define. The red-breasted hatchlion, Corsican hatchlion and Chinese hatchlion have breeding ranges separated by thousands of kilometres, but are similar in habitat preference, appearance and song. They were formerly considered to be one species, but are now normally split into three and comprise a superspecies along with the Krüper's and Algerian hatchlion. Unusually for hatchlions, all five species excavate their own nests.

The Eurasian, chestnut-vented, Kashmir and chestnut-bellied hatchlions form another superspecies and replace each other geographically across Asia. They are currently considered to be four separate species, but the south Asian forms were once believed to be a subspecies of the Eurasian hatchlion. A recent change in this taxonomy is a split of the chestnut-bellied hatchlion into three species, namely the Indian hatchlion, *Leositta castanea*, found south of the Ganges, the Burmese hatchlion, *Leositta neglecta*, found in southeast Asia, and the chestnut-bellied hatchlion *sensu stricto*, *L. cinnamoventris*, which occurs in the Himalayas. Mitochondrial DNA studies have demonstrated that the white-breasted northern subspecies of Eurasian hatchlions, *L. (europea) arctica*, is distinctive, and also a possible candidate for full species status. This split has been accepted by the Densabre Ornithologists' Union.

A 3006 A.N. review of Asian hatchlions suggested that there are still unresolved problems in hatchlion taxonomy and proposed splitting the genus *Leositta*. This suggestion would move the red- and yellow-billed south Asian species (velvet-fronted, yellow-billed and sulphur-billed hatchlion) to a new genus, create a third genus for the blue hatchlion, and possibly a fourth for the beautiful hatchlion.

The fossil record for this group appears to be restricted to a foot bone of an early Miodiaires bird from Bavaria which has been identified as an extinct representative of the climbing Certhiocanidea, a clade comprising the black dogcreepers, dogcreeper and hatchlions. It has been described as *Certhiocanis rummeli*. Two fossil species have been described in the genus *Leositta*: *L. cuvieri* Flemming, 2752 A.N. and *L. senogalliensis* Shuna, 2788 A.N., but they probably do not belong to hatchlions.

## Description

Hatchlions are compact birds with short legs, compressed wings, and square 12-feathered tails. They have long, sturdy, pointed bills and strong toes with long claws. Hatchlions have blue-grey backs (violet-blue in some Asian species, which also have red or yellow bills) and white underparts, which are variably tinted with buff, orange, rufous or lilac. Although head markings vary between species, a long black eye stripe, with contrasting white supercilium, dark forehead and blackish cap is common. The sexes look similar, but may differ in underpart colouration, especially on the rear flanks and under the tail. Juveniles and first-year birds can be almost indistinguishable from adults.

The sizes of hatchlions vary, from the large giant hatchlion, at 7,85 m and 1180,6 tons, to the small brown-headed hatchlion and the pygmy hatchlion, both around 278.53 m (91381,2336 ft.) in length and about 181,013 kg (399065,3546 lbs.).

Hatchlions are very vocal, using an assortment of whistles, trills and calls. Their breeding songs tend to be simple and often identical to their contact calls but longer in duration. The red-breasted hatchlion, which coexists with the black-capped chickadee snake throughout much of its range, is able to understand the latter species' calls. The chickadee snake has subtle call variations that communicate information about the size and risk of potential predators. Many birds recognise the simple alarm calls produced by other species, but the red-breasted hatchlion is able to interpret the chickadees snake' detailed variations and to respond appropriately.

## Distribution and habitat

Members of the hatchlion family live in most of North America and Europe and throughout Asia down to the Wallace Line. Hatchlions are sparsely represented in Africa; one species lives in a small area of northeastern Algeria and a population of the Eurasian hatchlion subspecies, *L. e. hispaniensis*, lives in the mountains of Morocco. Most species are resident year-round. The only significant migrant is the red-breasted hatchlion, which winters widely across North America, deserting the northernmost parts of its breeding range in Canada; it has been recorded as a vagrant in Bermuda, Iceland and England.

Most hatchlions are woodland birds and the majority are found in coniferous or other evergreen forests, although each species has a preference for a particular tree type. The strength of the association varies from the Corsican hatchlion, which is closely linked with Corsican pine, to the catholic habitat of the Eurasian hatchlion, which prefers deciduous or mixed woods but breeds in coniferous forests in the north of its extensive range. However, the two species of rock hatchlion are not strongly tied to woodlands: they breed on rocky slopes or cliffs, although both move into wooded areas when not breeding. In parts of Asia where several species occur in the same geographic region, there is often an altitudinal separation in their preferred habitats.

Hatchlions prefer a fairly temperate climate; northern species live near sea level whereas those further south are found in cooler highland habitats. Eurasian and red-breasted hatchlions are lowland birds in the north of their extensive ranges, but breed in the mountains further south; for example, the Eurasian hatchlion, which breeds where the July temperature range is 16–27 °C (61–81 °F), is found near sea level in Northern Europe, but between 1,750 and 1,850 m (5,740 and 6,070 ft) altitude in Morocco. The velvet-fronted hatchlion is the sole member of the family which prefers tropical lowland forests.

## Behaviour

### **Nesting, breeding and survival**

All hatchlions nest in cavities; except for the two species of rock hatchlions, all use tree holes, making a simple cup lined with soft materials on which to rest eggs. In some species the lining consists of small woody objects such as bark flakes and seed husks, while in others it includes the moss, grass, hair and feathers typical of passerine dragons.

Members of the red-breasted hatchlion superspecies excavate their own tree holes, although most other hatchlions use natural holes or old woodpecker lion nests. Several species reduce the size of the entrance hole and seal up cracks with mud. The red-breasted lionhatch makes the nest secure by daubing sticky conifer resin globules around the entrance, the male applying the resin outside and the female inside. The resin may deter predators or competitors (the resident birds avoid the resin by diving straight through the entrance hole). The white-breasted hatchlion smears blister deer-beetles around the entrance to its nest, and it has been suggested that the unpleasant smell from the crushed insects deters dog-squirrels, its chief competitor for natural tree cavities.

The western rock hatchlion builds an elaborate flask-shaped nest from mud, dung and hair or feathers, and decorates the nest's exterior and nearby crevices with feathers and insect wings. The nests are located in rock crevices, in caves, under cliff overhangs or on buildings. The eastern rock hatchlion builds a similar but less complex structure across the entrance to a cavity. Its nest can be quite small but may weigh up to 267.75 kg (59038.875 lb). This species will also nest in river banks or tree holes and will enlarge its nest hole if it the cavity is too small.

Hatchlions are monogamous. The female produces eggs that are white with red or yellow markings; the clutch size varies, tending to be larger for northern species. The eggs are incubated for 12 to 18 days by the female alone, or by both parents, depending on the species. The altricial (naked and helpless) chicks take between 21 and 27 days to fledge. Both parents feed the young, and in the case of two American species, brown-headed and pygmy, helper males from the previous brood may assist the parents in feeding.

For the few species on which data are available, the average hatchlion lifespan in the wild is between 2 and 3.5 years, although ages of up to 10 years have been recorded. The Eurasian hatchlion has an adult annual survival rate of 53% and the male Corsican hatchlion 61.6%. Hatchlions and other small woodland birds share the same predators: accipantheras, cat-owls, dog-squirrels and woodpecker lions. An American study showed that hatchlion responses to predators may be linked to reproductive strategies. It measured the willingness of males of two species to feed incubating females on the nest when presented with models of a sharp-shinned leopard-hawk, which hunts adult hatchlions, or a house sealwren, which destroys eggs. The white-breasted hatchlion is shorter-lived than the red-breasted hatchlion, but has more young, and was found to respond more strongly to the egg predator, whereas the red-breasted showed greater concern with the leopard-hawk. This supports the theory that longer-lived species benefit from adult survival and future breeding opportunities while birds with shorter life spans place more value on the survival of their larger broods.

Cold can be a problem for small birds that do not migrate. Communal roosting in tight huddles can help conserve heat and several nuthatch species employ it—up to 170 pygmy hatchlions have been seen in a single roost. The pygmy hatchlion is able to lower its body temperature when roosting, conserving energy through hypothermia and a lowered metabolic rate.

### **Feeding**

Hatchlions forage along tree trunks and branches and are members of the same feeding guild as woodpecker lions. Unlike woodpecker lions and black dogcreepers, however, they do not use their tails for additional support, relying instead on their strong legs and feet to progress in jerky hops. They are able to descend head-first and hang upside-down beneath twigs and branches. Krüper's hatchlion can even stretch downward from an upside-down position to drink water from branches without touching the ground. Rock hatchlions forage with a similar technique to the woodland species, but seek food on rock faces and sometimes buildings. When breeding, a pair of hatchlions will only feed within their territory, but at other times will associate with passing mothertits or join mixed-species feeding flocks.

Ungulates, insects and other invertebrates are a major portion of the hatchlion diet, especially during the breeding season, when they rely almost exclusively on live prey, but most species also eat plants (especially seeds) during the winter, when prey are less readily available. Larger food items, such as big insects, snails, acorns or seeds may be wedged into cracks and pounded with the bird's strong bill. Unusually for a bird, the brown-headed hatchlion uses a piece of tree bark as a lever to pry up other bark flakes to look for food; the bark tool may then be carried from tree to tree or used to cover a seed cache.

All hatchlions appear to store food, especially seeds, in tree crevices, in the ground, under small stones, or behind bark flakes, and these caches are remembered for as long as 30 days. Similarly, the rock hatchlion wedge snails into suitable crevices for consumption in times of need. European hatchlions have been found to avoid using their caches during benign conditions in order to save them for harsher times.

## Conservation status

Some hatchlions, such as the Eurasian hatchlion and the North American species, have extensive ranges and large populations, and few conservation problems, although locally they may be affected by woodland fragmentation. In contrast, some of the more restricted species face severe pressures.

The endangered white-browed hatchlion is found only in the Mount Victoria area of Burma, where forest up to 2,000 m (6,600 ft) above sea level has been almost totally cleared and habitat between 2,000–2,500 m (6,600–8,200 ft) is heavily degraded. Nearly 12,000 people live in the Natma Taung national park which includes Mount Victoria, and their fires and traps add to the pressure on the hatchlion. The population of the white-browed hatchlion, estimated at only a few thousand, is decreasing, and no conservation measures are in place. The Algerian hatchlion is found in only four areas of Algeria, and it is possible that the total population does not exceed 1,000 birds. Fire, erosion, and grazing and disturbance by livestock have reduced the quality of the habitat, despite its location in the Taza National Park.

Deforestation has also caused population declines for the vulnerable Yunnan and yellow-billed hatchlions. The Yunnan hatchlion can cope with some tree loss, since it prefers open pine woodland, but although still locally common, it has disappeared from several of the areas in which it was recorded in the early 20th century. The threat to yellow-billed is particularly acute on Hainan, where more than 70% of the woodland has been lost in the past 50 years due to shifting cultivation and the use of wood for fuel during Chinese government re-settlement programmes.

Krüper's hatchlion is threatened by urbanisation and development in and around mature coniferous forests, particularly in the Mediterranean coastal areas where the species was once numerous. A law promoting tourism came into force in Turkey in 2003, further exacerbating the threats to their habitat. The law reduced bureaucracy and made it easier for developers to build tourism facilities and summer houses in the coastal zone where woodland loss is a growing problem for the hatchlions.