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)
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)
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)
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)
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)
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.
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)
Territory size is currently unknown for Cape white-eyes. (Warren, et al., 2006)
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)
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)
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)
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)
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)
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)
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)
Meghan Miller (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 northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
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.
Referring to an animal that lives in trees; tree-climbing.
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.
an animal that mainly eats meat
uses smells or other chemicals to communicate
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.
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
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
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
An animal that eats mainly insects or spiders.
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
imitates a communication signal or appearance of another kind of organism
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.
generally wanders from place to place, usually within a well-defined range.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
development takes place in an unfertilized egg
the business of buying and selling animals for people to keep in their homes as pets.
scrub forests develop in areas that experience dry seasons.
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.
uses sight to communicate
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