letting nature back in

The Cape White-eye is another of my favourite garden birds that is no less special for being a familiar presence in suburban gardens. Cape White-eyes forage busily in small groups and they are enthusiastic visitors to the bird baths where, after drinking, they bathe with much exuberance.

Like most white-eyes, the Cape White-eye is an adaptable species. It occurs from the coast to the mountains, preferring wooded or bushy habitats, which include parks and gardens. Small foraging parties take their time searching systematically through trees and other vegetation gleaning insects from bark, branches and from under leaves. They also hawk insects on the wing and take spiders from their webs. In addition to preying on a variety of insects and spiders they also eat fruit and nectar.

A Cape White-eye in our garden with freshly caught prey. This is the yellower form found in the north eastern parts of the country. Other forms are much greyer on the flanks.

A Cape White-eye pausing while eating the ripe fruits from a Pigeonwood tree (Trema orientalis)

This Cape White-eye is looking for anything worth gleaning in a Crossberry (Grewia occidentalis)

Belonging to the large family Zosteropidae (the family name means girdle-eye), species of white-eye, occur throughout tropical and subtropical regions in sub-Saharan Africa, Asia and Oceania. For a distribution map see here. In Australasia common names for white-eyes include silvereye and wax-eye.

Interestingly, the Japanese White-eye was introduced into Hawaii in the 1920s as a form of insect control. The highly adaptable white-eyes have become so successfully naturalised that they are now outperforming the native birds, and their high numbers are leaving native species with too little to eat (see here for more). This is another cautionary and sad tale of a deliberately introduced species becoming a threat to indigenous species.

Cape White-eyes are agile and acrobatic while searching in trees and other plants for food. This one interrupted foraging in our garden to peer at me and my camera

Three species of white-eye are found in Southern Africa – the commonest and most widespread (though absent from arid regions) is the Cape White-eye, which is endemic to Southern Africa. The African Yellow White-eye occurs in parts of Namibia, Botswana, Zimbabwe, Mozambique and the north-eastern corners of Limpopo and KwaZulu-Natal provinces, and well as in several other sub-Saharan countries further to the north. The third species, the Orange River White-eye, occurs in Namibia and along the catchment areas of the Orange and the Vaal Rivers and in adjacent regions.

I photographed this Orange River White-eye appropriately enough on the banks of the Orange River (also known as the Gariep) in the Richtersveld – at the De Hoop campsite

According to the taxonomy followed by BirdLife International, across their range there are 138 species of white-eye (see here). Because of their unusually rapid (in evolutionary terms) diversification into a large number of separate species, white-eyes were dubbed the “Great Speciators”. For an interesting account of a study investigating this phenomenon – rapid speciation of white-eyes while simultaneously spreading across new geographic regions – see this post by GrrlScientist.

Cape White-eyes remain common because they thrive in a variety of habitats, despite their mortality rates being high, as is the case for many species of birds. The annual average mortality rate for adult Cape White-eyes is 35%. In Southern Africa, predators of the Cape White-eye include the African Cuckoo-Hawk, the Common Fiscal (also known as the Fiscal Shrike) and the Fork-tailed Drongo. Being very small, adult Cape White-eyes have been found entangled in spiderwebs and even impaled on cactus thorns. Only 50% to 57% of nestlings fledge, with many falling prey to predators such as Common Fiscals, Southern Boubous and Olive Thrushes as well as to the venomous snake known as the Boomslang (literal meaning is Tree snake).

The distinctive white feathers around the eye are characteristic of most species in the Zosteropidae family 

Despite being highly social birds, breeding pairs of Cape White-eyes are solitary nesters, with both parents building the nest, incubating the eggs (2 to 4 eggs per brood) and feeding and raising the young. Nests are made from a variety of mainly plant materials including lichen, dry grass stems, shreds of bark, tendrils and small roots, and the small cup-shaped nest is lined with fine grass-heads, hair or plant down. This material is bound with spiderweb that is also used to attach the nest hammock-style to a forked horizontal twig amongst the leaves of a tree or shrub. Many species of birds utilise spiderweb as an important nesting material – something to bear in mind for those who routinely eradicate spiders from their environs.

Visits to the birdbath tend to start demurely with a drink of water

Caution soon dissipates in a flurry of splashing and dipping as bath time commences

It only gets wilder as time goes on

This individual seems quite overcome after participating in the bath-time flurry

And this one seems solemn and somewhat sodden

After the commotion of bathing and preening a Zen-like calm prevails before the next foraging party congregates ahead of flying off to try their luck

Sources:

Chittenden, H., Davies, G. and Weiersbye, I. 2016. Roberts Bird Guide: Illustrating nearly 1,000 Species in Southern Africa (2^nd edition). Cape Town: Jacana; EurekAlert! 2009. Introduced Japanese white-eyes pose major threat to Hawaii’s native and endangered birds. https://www.eurekalert.org/pub_releases/2009-09/cp-ijw091009.php; GrrlScientist. 2009. Meet the Great Speciators: The White-Eyes. This Scientific Life. http://thisscientificlife.scientopia.org/2009/01/27/meet-the-great-speciators-the-white-eyes/; iNaturalist. 2018. White-eyes, Yuhinas, and Allies (Family Zosteropidae): Map https://www.inaturalist.org/taxa/17438-Zosteropidae; Roberts VII Multimedia PC Edition.  1997-2016 Southern African Birding. For details go to http://www.sabirding.co.za/roberts7/portal.html

Posted by Carol