Behavior And Reproduction
Fantails are known for holding their tail cocked, tilted to one side, alternately fanning and closing it, and swinging it from side to side while a bird is perched or moving around in the foliage, plant leaves. They also use this tail posture when in flight, performing highly aerobatic, looping flights in order to catch their insect prey. Viewed sometimes as "hysterical," the fantails tend to be restless, and rarely perch for long. Some species are more sedate, calmer.
Several fantail species are tame and easily approach humans while engaged in capturing insects, flushed out by a moving observer. They use other harmless larger animals in a similar way, willie wagtails often use domestic cattle both as a perch and to flush out insects. When an animal is perceived as predator, however, fantails can become extremely aggressive, even toward larger birds, attacking them and landing on their backs. Willie wagtails signal their aggression by giving a rasping, scolding call and expanding their white eyebrow. Territorial disputes that result in defeat will render the losing bird's white eyebrow invisible after it shrinks. Some fantails such as the thicket-fantails are shy and hard to see in the dense undergrowth they inhabit.
Tropical populations of fantails are sedentary, they do not migrate and live in the same area all year long. In some southern temperate, not too hot or cold, regions, and at the higher elevations, the fantails often travel considerable distances with the seasons. The rufous fantail of Australia moves north and south along the east coast on a regular basis. The southeastern populations of grey fantails travel long distances north and northwest during the winter. Such species as the white-throated and yellow-bellied fantails, spend the summer in the Himalayas and move to lower altitudes at the end of the summer.
Fantails are not noted for their songs, but have relatively pleasant voices. The calls are simple, and the voices tend to sound very delicate. When they do sing, the song tends to be rapid and full of enthusiasm. The gray fantail's song has been compared to the notes of a violin. The willie wagtail, again an exception, has a scolding call and strong song, with the ability to be heard at some distance.
The fantail breeding habits are virtually unknown in the rarer species, but widely studied in the more common. Most have similar breeding habits with both sexes building a nest that is a small, neat cup of fine grass stems bound by a thick external coating of cobwebs. They place their nest in a horizontal fork, or some other human-made structure or other suitable site, at a height of 3 to 50 feet (1 to 15 meters) off the ground, though usually within 10 feet (3 meters) of the ground. Fantails have been observed attaching a "tail" underneath the nest made of the nesting material. A clutch includes two to four eggs that are pale or cream colored and marked with brown or gray blotches and spots that form a wreath at the larger end of the egg or around its middle. Yellow-bellied fantails have cream or pinkish cream eggs with a cap on the larger end and pinkish brown flecks or small spots on the cap. Both parents incubate, sit on, the eggs over a time period of twelve to fourteen days. After they hatch the chicks stay in the nest for thirteen to fifteen more days, with both parents taking care of them.
Nests are not concealed and so are easy prey for larger birds. In an experiment, researchers constructed artificial nests with eggs made from modeling clay. The team observed that more than ten bird species and several small mammals attempted to steal the eggs. This was evident due to the bite marks found on the eggs. The eggs' major predator was the pied currawong, which conducted more than half of the raids. Nest parasitism from the cuckoo is also common. Cuckoo parents lay their eggs in the nest of other bird species, such as the fantail When the cuckoo chicks hatch, they push the other eggs from the nest and are raised by the host parents. The rufous fantail can be host to the begging young pallid cuckoo, which weighs more than eight times the size of the fantail.