Zosterops pallidusCape white-eye(Also: pale white-eye)

Geographic Range

Cape white-eyes (Zosterops pallidus) maintain the highest dispersal capabilities of all passerines. Although they occur mainly in South African savannas and suburban gardens they are found throughout the old-world tropic, which includes: Africa, Asia and Australia. Waves of immigration have occurred within the Southwest Indian Ocean islands such as: the Mascarenes, Comoros, Seychelles and Aldabras.

There are six subspecies that vary mainly in geographical location. (Z. p. virens) inhabits South-western Mozambique to Eastern Cape Province. (Z. p. caniviridis) ranges from Eastern Botswana to North-West Province and Limpopo Province. (Z. p. atmorii) dwells from inland Eastern Cape to Free State Province and Lesotho. (Z. p. capensis) inhabits Western Cape Province. (Z. p. pallidus) ranges from Southern Namibia to North-West Province and Northern Cape Province. (Z. p. sundevalli) dwells in Southern parts of Northern Cape Province. (; Cody, 1983; Craig, 1990; Warren, et al., 2006)

Habitat

Cape white-eyes are distributed throughout many different climatic regions from South Africa to islands throughout the Southwest Indian Ocean. They prefer semi-arid regions with diverse patches of vegetation such as suburban gardens, evergreen forests, and scrub forests. The annual rainfall within these semi-arid regions fluctuates around 550 mm with a minimum temperature in winter of -4 ˚C. They are found at elevations of up to 9,600 m. (Craig, 1990; Hully, et al., 2004; Martin, et al., 2007)

  • Range elevation
    sea level to 9600 m
    to 31496.06 ft

Physical Description

Cape white-eyes are small passerines that measure up to 12 cm in length and weigh about 9.15 g. These birds have rounded wings with a wingspan of 7 cm. Cape white-eyes' plumage is greenish yellow on the upper portions of the body with a gray upper back while the throat is a bright yellow. Their belly is usually a peach color and the most distinguishing feature is the white ring around their eyes. They go through no seasonal plumage color change. These birds feature black, short decurved beaks which aid in gathering nectar. The legs are either gray to brown or pink depending on age. Older birds and fledglings maintain a pinkish shade while first-years have grayish-brown coloration. Cape white-eyes are sexually monomorphic.

Some subspecies exhibit plumage differences, mainly in coloration of breast and belly. (Z. p. virens) and (Z. p. caniviridis) have a greenish-yellow breast and belly while (Z. p. atmorii) and (Z. p. capensis) have a gray coloration. (Z. p. pallidus) and (Z. p. sundevalli) feature a pale yellow belly with peach-colored flanks. (; Cody, 1983; Hully, et al., 2004)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    9.15 g
    0.32 oz
  • Average length
    12 cm
    4.72 in
  • Average wingspan
    7 cm
    2.76 in

Reproduction

Mate selection and breeding activity of Cape white-eyes is not well known due to few observations. When breeding season begins in November or December, males perform elaborately loud songs for about twenty minutes after daybreak and late in the evening. Their warbles are similar across different subspecies and they may also perform a softer warble in order to coax the female. Both sexes also produce a long-drawn plaintive call followed by shorter calls. While these calls are being performed, an aerial show of horizontal wing quivering and nest building motions are also being exhibited by the males. Cape white-eyes form life-long monogamous pairs, and may form pairs as early as one month old. (Hully, et al., 2004; Martin, et al., 2007; Wellmann and Downs, 2009)

Their breeding season can last for six months and usually occurs from September to December. Both males and females help construct a cup-shaped nest over a period of 5 to 9 days. The nest is constructed of old man’s beard (Usnea barbata), dry grasses, rootlets, and other such vegetation which is all held together by spider webs. Within this nest 2 to 4 pale blue eggs will be laid. Cape white-eyes have one of the shortest incubation periods of any birds which ranges from 11 to 12 days. Hatchlings initially weigh 2 g. It is also important to note that both females and males brood and feed the young. Once the chicks hatch they leave the nest after an estimated 12 to 13 days and stay close by during fledgling which lasts about three weeks. During these three weeks the parents continue to feed the fledglings fruit. While the fledglings are preparing to depart, a second clutch will usually be procured at a different nest site. (Hully, et al., 2004; Wellmann and Downs, 2009)

  • Breeding interval
    An older pair of Cape white-eyes may lay as many as five clutches during a breeding season where a first year pair may not breed at all.
  • Breeding season
    The breeding season takes place between September and December.
  • Range eggs per season
    2 to 4
  • Range time to hatching
    10 to 12 days
  • Average time to hatching
    11 to 12 days
  • Average fledging age
    12 to 13 days
  • Average time to independence
    5 weeks
  • Average age at sexual or reproductive maturity (female)
    1 months
  • Average age at sexual or reproductive maturity (male)
    1 months

Cape white-eyes put quite a bit of investment into taking care of their young. Both males and females participate in constructing a cup nest. The chicks are born altricial and helpless, and rely on both parents to brood, feed, and protect them. Both parents engage in attentive allopreening of the young and each other. When the young hatch the parents must find insects and later on fruit in order to feed them. A breeding pair will often begin a second clutch while still tending to the fledglings of the first. (Craig, 1990; Hully, et al., 2004; Warren, et al., 2006)

  • Parental Investment
  • altricial
  • male 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
  • post-independence association with parents

Lifespan/Longevity

Cape white-eyes are expected to live an average of 8 years in the wild. Captive birds are expected to live 10 years. This short lifespan likely correlates with rapid reproduction rates.

  • Range lifespan
    Status: wild
    9.2 (high) years
  • Average lifespan
    Status: wild
    7.8 years
  • Range lifespan
    Status: captivity
    10 (high) years
  • Average lifespan
    Status: wild
    8 years

Behavior

Cape white-eyes are diurnal and are known for being extremely social and for their frequent, loud vocalizations. Cape white-eyes are rarely seen alone and are mostly accompanied by a mate or large flock. The flock itself can be seen huddling together for warmth and comfort, bathing, resting and foraging together. In order to establish tight bonds, individuals often take part in allopreening of their offspring, mates, siblings, and prospective mates. Another key behavior is wing fluttering and bill clattering which demonstrate aggression which in turns establishes dominance. These dominance hierarchies influence mate selection. Some species of white-eyes do migrate and change plumage in winter however, Cape white-eyes do not. (Craig, 1990; Wellmann and Downs, 2009)

Home Range

Territory size is currently unknown for Cape white-eyes. (Warren, et al., 2006)

Communication and Perception

Cape white-eyes frequently communicate vocally, and are known for their noisy gatherings. They produce loud contact calls which which include descending musical notes. Often these calls are described mnemonically as “tirri-you, tirri-you, tirri-you” or “ti-you, ti-you, ti-you." Only male Cape white-eyes sing. These songs mostly imitate those of other birds in the area. Cape white-eyes also use beak clapping and quivering wings to intimidate other birds and communicate rank in the dominance hierarchy. Adults also allopreen offspring or mates to strengthen bonds. Like all birds, Cape white-eyes perceive their environment through visual, tactile, auditory and chemical stimuli. (Cody, 1983; Hully, et al., 2004)

  • Other Communication Modes
  • mimicry

Food Habits

Cape white-eyes are known to eat insects, fruit, nectar, and seeds. Insects in which they prey upon include: insect larvae, flies, grasshoppers, millipedes, spiders and beetles. An important staple of these birds' diets are aphids due to easy digestion and nutritional value. They consume nectar from Australian bottle brushes (Calistemon rigidus) and other plants by using their specialized, brush-tipped tongue. Cape white-eyes also consume seeds and have recently become frequent feeder birds. (Kopij, 2004)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • seeds, grains, and nuts
  • fruit
  • nectar

Predation

Cape white-eyes have been known to be preyed upon by cuckoo hawks (Aviceda cuculoides), common fiscals (Lanios collaris) and fork-tailed dronges (Dicrurus adsimilis). Domestic cats are also predators of Cape white-eyes. Some anti-predator adaptations that they have acquired include camouflage, vocalizations and flock advantages. The greenery of their plumage allows them to blend in easily with their habitat and when danger is near warning calls are given. (Craig, 1990)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Cape white-eyes serve as prey to larger predators such as cuckoo hawks (Aviceda cuculoides), common fiscals (Lanios collaris) and fork-tailed dronges (Dicrurus adsimilis). Domestic cats also greatly reduce the numbers of Cape white-eyes. Cape white-eyes prey upon a variety of insects, fruits, nectar and seeds. As they consume seeds and nectar, these birds are likely important pollinators and seed dispersers for local plant species. Cape white-eyes also participate in a behavior known as 'anting'. The birds allow ants to crawl within their feathers and feed on bacteria. This is considered a mutualistic partnership in that the ants are provided with food and Cape white-eyes do not eat those that have been on their feathers. (Craig, 1990; Kopij, 2004)

  • Ecosystem Impact
  • disperses seeds
  • pollinates
Mutualist Species

Economic Importance for Humans: Positive

Cape white-eyes are very vocal songbirds, and as a result are often caged and kept as pets by humans. Cape white-eyes also consume a lot of aphids and other pests that are mostly found around farms and gardening plants. This ecosystem function aids in the preservation of crops and gardens allowing humans to produce healthier vegetation. (Allan, et al., 1996)

  • Positive Impacts
  • pet trade
  • controls pest population

Economic Importance for Humans: Negative

Though Cape white-eyes do not have any real known adverse effects on humans they do create a problem in one area. Cape white-eyes tend to be a nuisance in vineyards and orchards in Southern Africa and Australia due to their large numbers and consumption of fruit. (Cody, 1983; Craig, 1990)

  • Negative Impacts
  • crop pest

Conservation Status

Cape white-eyes are not threatened, however other species of white-eyes are at risk. Many species who maintain residency on small isolated islands are suffering from habitat loss, introduction of new predators, and frequent severe storms. The IUCN Red List states that Cape white-eyes are of least concern, but recent population declines may qualify the species for re-evaluation in the future. (Allan, et al., 1996; Warren, et al., 2006)

Contributors

Meghan Miller (author), Northern Michigan University, Alec Lindsay (editor), Northern Michigan University, Rachelle Sterling (editor), Special Projects.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

altricial

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.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

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.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

endothermic

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.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

iteroparous

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).

male parental care

parental care is carried out by males

mimicry

imitates a communication signal or appearance of another kind of organism

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nomadic

generally wanders from place to place, usually within a well-defined range.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

parthenogenic

development takes place in an unfertilized egg

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

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).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

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.

savanna

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.

temperate grassland

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.

visual

uses sight to communicate

References

Allan, D., J. Harrison, R. Navarro, B. van Wigen, M. Thompson. 1996. The impact of commercial afforestation on bird populations in Mpumalanga Province, South Africa--Insights from bird-atlas data.. Biological Conservation, 79(2-3): "173-185".

Brown, K., C. Downs. 2003. Digestive efficiency of a generalist avian feeder, the Cape White-eye (Zosterops pallidus). Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology, 134(4): "739-748".

Cody, M. 1983. Bird diversity and density in south african forests. Oecologia, 59(2): "201-215". Accessed January 14, 2010 at http://dx.doi.org/10.1007/BF00378838.

Craig, R. 1990. Foraging Behavior and Microhabitat Use of Two Species of White-Eyes (Zosteropidae) on Saipan, Micronesia. The Auk, 107(3): "500-505".

Hully, P., A. Craig, G. Underhill. 2004. Timing of moult and breeding in the Cape White-eye, Zosterops pallidus, from three different geographical regions in South Africa. Emu, 104: "353-358".

Kopij, G. 2004. Summer and winter diet of the Cape white-eye Zosterops pallidus in South African grassland. African Journal of Ecology, 42(3): 237-238.

Martin, T., S. Auer, R. Bassar, A. Niklison. 2007. GEOGRAPHIC VARIATION IN AVIAN INCUBATION PERIODS AND PARENTAL INFLUENCES ON EMBRYONIC TEMPERATURE. Evolution, 61(11): "2558-2569".

Symes, C. 2001. Movements and timing of moult and breeding of the Cape White-eye Zosterops pallidus in Kwazulu-Natal.. Afring News, 30: 35-39. Accessed January 16, 2010 at http://web.uct.ac.za/depts/stats/adu/pdf/afring_news30_1.pdf#page=35.

Warren, B., E. Bermingham, R. Prys-Jones, C. Thebaud. 2006. Immigration, species radiation and extinction in a highly diverse songbird lineage: white-eyes on Indian Ocean islands. Molecular ecology, 15(12): "3769-3786".

Wellmann, A., C. Downs. 2009. A behavioural study of sleep patterns in the malachite sunbird, Cape white-eye and fan-tailed widowbird. Animal Behaviour, 77(1): "61-66".