Common waxbills (Estrilda astrild) are native across much of sub-Saharan Africa. The species has been introduced to the Americas, the Mediterranean Basin, and Oceania. A high reproductive rate and ability to adapt to new food sources have allowed common waxbills to successfully naturalize in many of the areas to which it has been introduced. While most of these introductions are thought to result from the escape of caged individuals, some regions have introduced flocks deliberately. (Oren and Smith, 1981; Reino and Silva, 1998)
Common waxbills inhabit damp grassy areas, preferring those near wetlands. They breed and nest among reed beds, tall grasses, riverside vegetation, and dense bushy cover. They may also be found in a number of open mesic habitats such as farmlands and parks. (Reino and Silva, 1998)
Estrilda astrild is a small grey-brown colored finch, distinguished by its red conical bill and face patch. The bill looks as if it has been dipped in red wax, providing explanation to the origin of their common name, common waxbills. The cheeks, throat, and belly are a whitish-grey color, while the rest of the plumage is finely barred and the underside has a dusting of red. Adult common waxbills have a wingspan between 12 and 14 cm, and length of about 11.5 cm. They weigh approximately 8.9 g. The species has a fairly long, slender tail and rounded wings. Females are paler overall with less red along the belly. The plumage of juveniles is duller than the adults, having little red on the underbelly, and no red on the bill. Nestlings have obvious white gape flanges along the edges of their mouths. (Burton and Burton, 2002; Schuetz, 2004a)
According to Traylor et al., there have been 16 recognized subspecies of Estrilda astrild. However, there is very little information available on these subspecies. Black-lored waxbills (Estrilda nigriloris), was once considered a subspecies of common waxbills, but is now recognized as its own species. (Baillie, et al., 1990; Cottrell, et al., 1987)
Finches of the genus Estrida are monogamous, mating with only one partner. Song and display are both important aspects of courtship, and pair formation usually begins with a "curtsy" and song exchange between the two prospective mates. Allopreening occurs frequently between the mates. During the nest building and solicitation period, both males and females may participate in stem displays to their mates – a form of display during which a stem is held in the beak. The male sings an irregular pattern during this a display, while the female remains silent. After pairing off, they separate from the larger flock and breed singly. They may, however, be found in small territories adjacent to other pairs. (Kunkel, 1967; Schuetz, 2004a)
Males will also display to other females in the flock (those which are not his mate), but this display does not begin with a curtsy and is a type of “fluffed singing”. During this display the male positions his body to present the female with his red belly patch. He does this by placing one flank toward the female and outstretching his neck, holding his head high. He fluffs up his ventral and flank feathers, twists his tail toward the female, and the sings loudly. Females almost always flee when they receive these displays, being that they are advances from males with whom they are not mated. Males will attempt to mate with females which do not flee from his advances. (Kunkel, 1967)
The breeding season for Estrilda astrild takes place in midsummer, except in winter-rainfall areas (such as Southern Africa) where the breeding season is between September and January. The nest is a weaved, spherical mass of grasses with a narrow entrance. Nests are generally on or near the ground, hidden in similar, grassy vegetation. They have a clutch size between 4 and 6 eggs, and may raise several broods a year. The incubation period lasts 11 to 12 days with both sexes working to incubate the eggs. Fledging takes 17 to 21 days and during this time both parents feed and care for the chicks. Common waxbill juveniles reach reproductive maturity between 6 months and 1 year of age. (Burton and Burton, 2002)
Common waxbills build spherical nests out of dry grasses and keep them hidden in reeds close to the ground. The female does most of the nest-building, but the male assists in decorating it and lining the inside with feathers. Both parents spread animal scat in the nest throughout the nesting period as a way to divert predators. A unique feature to common waxbill nests is the formation of a separate “cock’s nest” located atop the main nest. No one is certain what the purpose of this secondary nest is, but it appears to be a resting place for the parent who is not incubating the nest. (Kunkel, 1967; Schuetz, 2004b)
Both male and female common waxbills incubate and feed the helpless, altricial young. The nests of common waxbills are often utilized by brood parasites such as pin-tailed whydahs (Vidua macroura), and the waxbill parents dotingly care for these parasitic young alongside their own. (Schuetz, 2004b)
Common waxbills live an average of 4 years in the wild. (Burton and Burton, 2002)
Estrilda astrild finches are very social, both in song and display. They assemble together during the day in flocks of 20 to 40 to forage together in reeds. During the evening they form an even larger group for roosting. In the breeding season individuals will separate into pairs and stay monogamous. They are contact birds and mates often participate in mutual grooming, known as allopreening. (Kunkel, 1967)
Territory size for common waxwings is currently unknown.
Common waxbills use both song and body language to communicate. The song of Estrilda astrild is a soft, simple call with notes varying only slightly in pitch and length from the contact note. A common body movement for this species is a “curtsy”, where the body is crouched with the head slightly turned, accompanied by soft singing. Females will sing more smoothly during this display, while males sing in a shorter series of notes. To impress a female, males fluff their feathers, point their bills upwards, and position their bodies so that their red underbellies are displayed clearly. Strong lateral movements with the tail are also used by both sexes during a number of different social encounters. Mates will perform mutual preening to establish or strengthen their pair-bond. Like all birds, common waxbills perceive their environment through visual, tactile, auditory and chemical stimuli. (Kunkel, 1967)
Common waxbills are granivores, living on a diet mainly of seeds from pasture grasses and millets. Of these, guinea grasses (Panicum maximum) are perhaps the most important dietary components for waxbills as they have seed heads available year-round. Other important seed prodeucers include crabgrass (Digitaria horizontalis) and Echinochloa species. Depending on a plant’s structure, common waxbills may either perch on the panicle while plucking seeds, or will pull the panicle to the ground, holding the plant with one foot and steadying itself on the ground with the other. Seed removal is done with the bill in both cases. They forage in flocks of 2 to 20 during the day, feeding mostly in early morning and late afternoon. (Kunkel, 1967; Oren and Smith, 1981)
Common waxbill young have an increased risk of predation as a result of their nests being placed so close to the ground. Mice and snakes are examples of the types of predators that will target common waxbill eggs and young. In a defensive response to this, the parents spread carnivore scat in and around the nest site to deter predators. The most commonly used scat comes from servals (Leptailurus serval), a type of large, African cat. The odor of the scat may be working to both deter predators from approaching the area, and also to mask the smell of the eggs and young themselves. (Schuetz, 2004b)
Common waxbills have different ecological roles depending on their location. In their native African landscape they have a minimal impact on the plant species they eat. However, this is not the case in some of the regions where they have been introduced. In Cape Verde and Seychelles, for example, invasive common waxbill populations have been shown to have a destructive impact on the crops they consume. As granivores, common waxbills likely play a significant role in seed dispersal for plants they consume. (Silva, et al., 2002)
Despite its role as an invasive species, there are no reports showing that common waxbills will serve to displace native species. In Brazil, a relatively new range for Estrilda astrild, they are reported to feed mostly on introduced grass species which are eaten only sparingly by native Brazilian bird species. Therefore it is seen as unlikely that common waxbills will displace any native bird species in that region. (Oren and Smith, 1981)
The nests of common waxbills are known host sites for pin-tailed whydahs (Vidua macroura), a well known brood parasite. Pin-tailed whydah chicks have evolved gape patterns that exactly match the gape patterns of common waxbill young, so that they are more likely to be accepted by waxbill parents. This relationship is harmful to the breeding success rate of common waxbills, but essential to the survival of pin-tailed whydahs. (Schuetz, 2004b)
Estrilda astrild finches are frequently kept caged as songbirds for human enjoyment.
Common waxbills can be detrimental to crops in some areas. This seems to be most often reported in regions where waxbills are non-native. Tomato crops in Cape Verde are one documented case which Estrilda astrild populations had a directly negative impact. (Silva, et al., 2002)
Common waxbills are not a threatened species. They are, instead, presently expanding their range and populations into new regions. (Reino and Silva, 1998)
Lauren Tarr (author), Northern Michigan University, Alec Lindsay (editor), Northern Michigan University, Rachelle Sterling (editor), Special Projects.
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the southern part of the New World. In other words, Central and South America.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
parental care is carried out by males
marshes are wetland areas often dominated by grasses and reeds.
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
the business of buying and selling animals for people to keep in their homes as pets.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
living in residential areas on the outskirts of large cities or towns.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
living in cities and large towns, landscapes dominated by human structures and activity.
uses sight to communicate
breeding takes place throughout the year
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