Fairy pitta

The fairy pitta mostly feeds on the ground, wandering solitarily. Its diet largely consists of earthworms of several species, beetles, and other hard-shelled insects.[7][12] A variety of other small animals such as lepidoptera larvae and adults, spiders, snails, lizards, frogs, small snakes, and shrews, occasionally form part of its diet.[10] Earthworms make up 73%-82% of the diet fed to the nestlings, followed by homoptera larvae (4%-8.6%).[12] Although not entirely identifiable, lepidopteran adults and pupae likely make up 11% of the nestling diet.[12] The fairy pitta's preference for earthworms with their high energy content makes the abundance of this food item critical for nesting success.

The fairy pitta makes a relatively large nest in the dark place, such as in the crevice between rocks in thick broadleaf forest or foliage on a slope, 1–5 m above the ground.[6][7][9] The entrance is lined with cattle dung[6] and the nest itself is lined with lichen. If necessary, the male aggressively defends the nest, chases after and attacking intruders. Such defensive behavior is only displayed until the eggs are laid.[8]

The female lays from 4 to 6 eggs per bredding attempt, from May to mid-July. The egg has a light gray background with small light brownish purple and grey dots, and is 25–27.5 mm in the major axis and 19–22.5 mm in the minor axis. Both male and female incubate the eggs; the female usually feeds the hatchlings, while the male keeps watch.[6][7] In the first 4 days after hatching, the fairy pitta rarely leaves the nest. This is probably because temperatures are low during the rainy season and the nestling hatches without any down feathers.[10] The nestling has its first plumage within 14 days after hatching.[7] Throughout the breeding season, the adult bird rarely goes farther than 100–400 m from the nest. In June or July, the chick fledges, but the rearing continues until the nestling is ready to migrate south.[9] The average reproductive success of the fairy pitta is 41.9%.[10]

The predators most affecting the reproductive success of the fairy pitta are snakes, followed by mammals such as macaques, cats and weasels. The raiding of nests by jungle crows (Corvus macrorhynchos) and cat snakes during breeding season has also been reported frequently. During migrations, the bird is exposed to danger from falcons. The rate at which adult fairy pittas return from the wintering grounds appears to be 16-26%;[10] most casualties happening on the bird's northward migrating and during breeding seasons from May to July. Fewer birds are lost during the autumn migration in October. Another cause of mortality is window strikes. As for many other species of bird, casualties from human-bird interaction are identified as a leading cause of decline in the fairy pitta.[11]

There is no very accurate estimate of total population size of the species. Estimated numbers include ranges of 100 to 10,000 breeding pairs and 50 to 1,000 migrating individuals respectively in China, Korea, Japan, and Taiwan; total population size is thought to be somewhere between a few thousand and a few tens of thousands of individuals.[3] Although researchers estimate that the largest number of birds survive in China, no concrete study has been done.[4] However, a worldwide trend of decline in the fairy pitta is clear enough to lead to a classification of the species as Vulnerable on the IUCN Red List of Threatened Species and as Endangered in CITES Appendix II. The main causes for the decline are habitat loss, trapping, hunting, and human disturbances.[3]

The causes of habitat disruption, which encompasses deforestation in the bird's breeding range, are essentially the results of human activity, but the characteristics of threats vary from one region to another. In Japan, where the fairy pitta was originally more common, significant areas of forest have been cleared since the 19th century for fuel and throughout the 20th century for the building of plantations.[10] Since the logging has ceased and old growth forests have begun to recover, the fairy pitta population is expected to gradually increase.[9] In contrast, vast forested areas in Southeast China have in the last 50 years been clear-cut or converted due to an increased demand for timber and farmland. There is also a lack of control of forest fires.[3][9] In Borneo, a fairy pitta wintering ground, the continuing destruction of the Sundaic lowland primeval forest is more devastating. It is one of the most important Biodiversity hotspots in the world, but the deforestation is ongoing even in the protected areas and jeopardizing not only the fairy pitta, but also many other tropical species.[9] Large scale developments also endanger local populations. In Yunlin County, Taiwan, the largest known breeding group of the species is being severely impacted by the flooding from the Hushan Dam project.[3] Despite the imminent threats that the fairy pitta is facing in Taiwan, however, quantitative data on the impact of human disturbance on the population remains limited, undermining the conservation efforts.[11]

The threat of hunting has been prevalent in Guangxi, China and Taiwan. Particularly in Taiwan, specimen-collecting and cage-bird trading are thought to have severely reduced the local breeding population in the 20th century. However, as more conservation efforts are made and the significance of the fairy pitta is recognized locally, hunting is expected to diminish.[9]

Human disturbances also directly affect individual fairy pittas. In Jeju Island, South Korea, window strikes are one of the leading factors endangering the bird. As more buildings are built in the vicinity of breeding sites, accidental window strikes have consequently increased.[11] Moreover, in Taiwan as well as in Jeju Island, many nests are disturbed by hikers, amateur photographers, birdwatchers, and researchers, which may alter the bird's behavior and increase nest predation risk.[3][9][11]

On a meta-population level, it is thought that the fairy pitta's relatively narrow distribution in Northeast Asia and the species' regionally specific breeding and wintering grounds are lowering the genetic diversity and fragment the genetic structure of populations. Although more research is needed, this is suspected to compromise its fitness.[4]

As a response to rapidly declining populations in most areas, an increasing number of studies has focused on the fairy pitta in recent years,[4] and the species is now protected under various national conservation laws.[3] The fairy pitta is classified as a Nationally Protected Species in China, Category II protected species in Taiwan, National Endangered Species in Japan, Category I protected species in North Korea,[9] and a Natural Monument in South Korea.[4] Many pairs benefit from breeding in national parks or reserves that were initially designed to protect other species.[3]

Conservation of the fairy pitta requires measures specific to local levels and international cooperation, since the species is exposed to various threats during migration and stopovers.[4] It has been suggested that more surveys of breeding sites, population sizes, and distribution of the bird be conducted along with research into its ecology, current conservation measures in parks, and the need for more sanctuaries.[3][9] Enforced management of existing protected forests and restrictions on hunting and trapping are critical for saving the species.[3] Specific measures for individual regions have been proposed. On Jeju Island, for instance, it has been advised that developments – including the construction of buildings, golf courses, roads, and trails – in forested or near breeding areas be regulated, and that a predator control program reducing the number of jungle crows and Eurasian magpies (Pica pica) should be considered.[11]