letting nature back in

The thrushes are as busy as ever this winter. Only two species of thrush visit our garden, out of the 12 or so species found in South Africa.

Thrushes occur all over the world, and the broad family (Turdidae) is split into two groups: true thrushes and chats. These categories are subject to revision over time, and some authorities include flycatchers in the chats section of the grouping.

There are over 60 species of true thrushes (Turdus), including in Europe the Blackbird, and in North America the American Robin (which got its name on account of its red breast, and not because it is a robin). I should think that I am one of many who count thrushes among their favourite garden birds?

One of the thrushes that visit our garden is the Kurrichane Thrush (pictured in both photos above). Typically, thrushes are ground foragers and eat a wide variety of invertebrates and fruit, with some also eating lizards and nestling birds 

Like most thrushes, the Kurrichane Thrush is usually found in woodland-type or bushy habitats and has adapted to well-vegetated suburban areas and gardens. It also lives in exotic plantations, valley bushveld and riverine bush, avoiding forests as well as arid savannah. Kurrichane Thrushes are usually resident although some may be altitudinal migrants in the winter, overwintering at lower altitudes.

The name Kurrichane derives from the word Kaditshwene, the name of the ancient capital of the baHurutshe people, descendants of a baTswana lineage. Founded because of the nearby rich iron-ore and copper deposits, Kaditshwene was occupied from as early as 1470 until the 1820s. A visiting British missionary in the early 1820s estimated the population of the capital to be between 16000 and 20000 people, which he estimated was twice the size of contemporary Cape Town.

Just to digress further (as I found this history to be interesting), later in the 1820s the capital was devastated during a period of ongoing instability and widespread conflict between rival chiefdoms. Its stone walled buildings were reduced to rubble and the area (in what is now the Zeerust district in North West Province, South Africa) was evacuated with the population dispersing as refugees.

Kaditshwene was named after a nearby mountain, itself named for the large number of resident baboons.  British missionaries visiting in the early 1820s noted down the name ‘Kaditshwene’ as they heard it. Notations are various and include the form ‘Kurrichane’. To better approximate the Setswana pronunciation (the ‘d’ is soft) it would be better to notate it as Kur-ree-cha-ne.

In the 1930s, long after the city had been abandoned, a visiting British naturalist/collector (and medical doctor) Andrew Smith collected specimens of two species of bird there, and named them after the region, using the corrupted English spelling, and so today we have the Kurrichane Thrush and the Kurrichane Buttonquail.

The second species of thrush to visit our garden is the Olive Thrush, mundanely named for the olive-grey colouring of their backs. They are almost always in our garden, and generally they are bolder than the Kurrichane Thrush. Currently, we are making a new flower bed by layering newspaper and cardboard on a patch of lawn, covering it in partly decayed compost and then lots of leaf litter – the thrushes and other ground foragers find plenty to eat here as they flick through the leaves 

Many thrushes are noted songbirds, including of course the European Blackbird. The Olive and Kurrichane Thrushes are also tuneful songsters, and both species sometimes copy the calls of some other species. Their song forms a vibrant part of the pre-dawn chorus during the breeding season.

Both the Kurrichane and Olive Thrushes are enthusiastic and energetic when it comes to bathing, dipping their heads under the water and emerging to flutter their wings and tail, getting a thorough soaking, as can be seen in this photo of a Kurrichane thrush commencing its bath in our garden pond. I have also seen Olive Thrushes dust bathing 

Most thrushes are monogamous, with the female building the nest and usually incubating the eggs, although in the Olive Thrush the male also takes turns incubating. Both parents participate in raising the chicks. Typically, they are very devoted parents when caring for the nestlings and then the vulnerable fledglings, and they continue looking after their young for about two months after they have fledged.

An Olive Thrush in typical pose, pausing while finding insects and worms in the fallen vegetation beneath the trees

 Illustrating the strength of parental devotion in the Kurrichane Thrush, Roberts (Multimedia version) describes an incident when a ‘lost’ chick, was adopted by people and housed in a cage in their garden, where days later it was fed by its parents through the bars of the cage.

Roberts also reports on some cases of cross-species feeding, that is where parents from one species feed the offspring of another. For example, a pair of African Paradise-Flycatchers that had lost their own brood, redirected their parental care, feeding Kurrichane thrush chicks in a nearby nest, even temporarily driving the parent thrushes away. In the end, all three chicks fledged and continued to be fed by all four ‘parents’. Roberts also mentioned a juvenile Groundscraper Thrush successfully begging food from a passing Kurrichane Thrush.  For more on cross-species feeding in birds see here

The Kurrichane and Olive thrushes are closely related, although they continue to be classified as separate species, with each species comprising several subspecies. Their ranges overlap in the eastern area of South Africa and Roberts (Multimedia version) reports that in these areas they are usual separate on the basis of habitat types (Olive Thrushes preferring evergreen forests avoided by Kurrichane Thrushes), but that the two species do co-occur in human-modified environments of intermediate vegetation density. However, as both species occur naturally in riverine bush and similar habitats, can we be sure that co-occurrence is only in human modified habitats?

Interestingly, several cases of hybrid Olive and Kurrichane thrushes have been recorded – annoying for the purists among us, frustrating for what is already a complex taxonomy, and if co-occurence is human induced perhaps a cause for concern?

Fascinating questions, such as how static species are, how and why species and family classifications are subject to change, and why the matter of natural hybridisation tends to raise human emotions, are complex topics worthy of further exploration.

Sources: 

Boeyens, Jan C.A. and Cole, Desmond T.  Kaditshwene : What’s in a name? Unisa Institutional Repository.  http://uir.unisa.ac.za/bitstream/handle/10500/19464/Finlayson__R__9781868881383__Section8.pdf?sequence=10&isAllowed=y  (pdf)

 Cross-species feeding.  (BTO:  Looking Out for Birds. British Trust for Ornithology) .https://www.bto.org/volunteer-surveys/gbw/gardens-wildlife/garden-birds/behaviour/cross_species_feeding

Kaditshwene  http://kaditshweneheritage.co.za/historical-background/

Roberts VII Multimedia PC Edition.  1997-2016 Southern African Birding. For details go to http://www.sabirding.co.za/roberts7/portal.html

Turdidae – Thrushes.  (BTO: Looking out for birds. British Trust for Ornithology). https://www.bto.org/about-birds/birdfacts/bird-families/thrushes

Posted by Carol