Estrilda astrild

Geographic Range

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.

• Biogeographic Regions
• nearctic nearctic
  • introduced introduced
• palearctic palearctic
  • introduced introduced
• ethiopian ethiopian
  • native native
• neotropical neotropical
  • introduced introduced
• australian australian
  • introduced introduced
• oceanic islands oceanic islands
  • introduced introduced

Habitat

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.

• Habitat Regions
• temperate temperate
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland

• Wetlands
• marsh marsh

• Other Habitat Features
• urban urban
• suburban suburban
• agricultural agricultural
• riparian riparian

Physical Description

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.

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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes colored or patterned differently
• male more colorful

Reproduction

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.

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.

• Mating System
• monogamous monogamous

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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

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.

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.

• Parental Investment
• altricial altricial
• male parental care male parental care
• female parental care female parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• pre-independence
  • provisioning
    • male
    • female
  • protecting
    • male
    • female

Lifespan/Longevity

Common waxbills live an average of 4 years in the wild.

Behavior

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.

• Key Behaviors
• flies
• diurnal diurnal
• motile motile
• sedentary sedentary
• solitary solitary
• social social

Home Range

Territory size for common waxwings is currently unknown.

Communication and Perception

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.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

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.

• Primary Diet
• herbivore herbivore
  • granivore granivore

• Plant Foods
• seeds, grains, and nuts

Predation

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.

Ecosystem Roles

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.

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.

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.

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

Estrilda astrild finches are frequently kept caged as songbirds for human enjoyment.

• Positive Impacts
• pet trade pet trade

Economic Importance for Humans: Negative

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.

• Negative Impacts
• crop pest

Conservation Status

Common waxbills are not a threatened species. They are, instead, presently expanding their range and populations into new regions.

Additional Links

Encyclopedia of Life

Contributors

Lauren Tarr (author), Northern Michigan University, Alec Lindsay (editor), Northern Michigan University, Rachelle Sterling (editor), Special Projects.

References

Baillie, J., B. Groombridge, World Conservation Monitering Centre, International Union for Conservation of Nature and Natural Resources. Species Survival Commission, BirdLife International. 1990. 1996 IUCN Red List of Threatened Animals . Washington, DC: IUCN.

Birchenough, A., G. Douglas, S. Evans. 2003. Assessing the distribution of estrildid finches on Vanuatu using local knowledge. Bird Conservation International , 13: 29-44.

Burton, M., R. Burton. 2002. The Wildlife Encyclopedia . Tarrtown, New York, USA: Marshall Cavendish Corporation.

Cottrell, G., J. Greenway, E. Mayr, R. Paynter, J. Peters, M. Traylor, Harvard University Museum of Comparative Zoology. 1987. Check-list of Birds of the World . Cambridge: Havard University Press.

Kunkel, P. 1967. Displays Facilitating Sociability in Waxbills of the Genera Estrilda and Lagonosticta (Fam. Estrildidae). Behaviour , Vol 29 No 2/4: 237-261.

Moulton, M., D. Ferris. 1991. Summer diets of some introduced Hawaiian finches. The Wilson Bulletin , 103 (2): 286-292.

Oren, D., N. Smith. 1981. Notes on the Status of the Common African Waxbill in Amazonia. Wilson Ornithological Society , Vol. 93, No. 2: 281-282.

Reino, L., J. Moya-Larano, A. Claudio Heitor. 2008. Using survival regression to study patterns of expansion of invasive species: will the common waxbill expand with global warming?. Ecography , Vol.32, Issue 2: 237-246.

Reino, L., T. Silva. 1998. The distribution and expansion of the common waxbill (Estrilda astrild) in the Iberian Peninsula. Biological Conservation Fauna , 102: 163-167.

Reino, L. 2005. Variation partitioning for range expansion of an introduced species: the common waxbill Estrilda astrild in Portugal. Journal of Ornithology , Vol 146 No 4: 377-382.

Schluter, D., R. Repasky. 1991. Worldwide Limitation of Finch Densities by Food and Other Factors. Ecology , 72, No 5: 1763 - 1774.

Schuetz, J. 2004. Common waxbills use carnivore scat to reduce the risk of nest predation. Behavioral Ecology , Vol 16 no 1: 133-137.

Schuetz, J. 2004. Reduced growth but not survival of chicks with altered gape patterns: implications for the evolution of nestling similarity in a parasitic finch. Animal Behaviour , 70, issue 4: 839-848.

Silva, T., L. Reino, R. Borralho. 2002. A model for range expansion of an introduced species: the common waxbill Estrilda astrild in Portugal. Diversity and Distributions , 8: 319-326.