South African Taxonomy

taxonomy

Southern Black Korhaan. Copyright: Trevor Hardaker

Taxonomic issues, especially among bird populations that vary morphologically, have been a hot topic of discussion for many years. Scientists gave many subjective opinions on how to decide what a "species" was and, in fact, these debates still rage on currently. As the various definitions of what a "species" is gain or lose favour, populations are either lumped together into one species or else they are split into several species. It is imperative to bear in mind that all life is constantly evolving and that it becomes increasingly more difficult to place these changing forms into set categories. However, most recent lumping and splitting has taken place as a result of changes in the definition of a species.

Up until the late 1980s, the Biological Species Concept (BSC) was used by almost everyone. This defined species as groups of individuals that are able to interbreed, as distinct from individuals in other species that are reproductively isolated. Unfortunately, all theories have their problems and, with more and more regularity, what were originally considered to be 'good' species have been found to interbreed at least occasionally, and they often produce viable offspring. Another problem was the status of populations that have disjunct distributions (i.e. have two or more isolated populations). These populations often look the same, but whether they interbreed or not, is never known because they never meet.

Recently, a new species concept has been put to the world and is fast gaining favour among scientists. The Phylogenetic Species Concept (PSC) defines species as groups of individuals that share at least one common, derived character (i.e. a character that has recently evolved). It seems to have addressed many of the problems of the BSC, but it has raised a whole new set of problems, especially for the "unscientifically-minded" birder. Based on the BSC, many populations that varied from one region to another were defined as single species, whilst now, by using the PSC, they are being split into a number of new 'species'. Following on from this, it would mean that, under the PSC, populations on different continents would be regarded as different species. The major problem with this is that often, these separate species are morphologically exactly the same and birders will have to begin accepting that not all birds will be able to be identified to full species level.

What does this mean to birders? Well, for those birders who actively keep a life list of all the birds they have seen, it would mean that they could gain many "armchair ticks" on their list. These would be birds that they have already seen, but that were considered to be subspecies of another species that already appeared on their list. Now, instead of having one species on their list, they would have at least two, depending on what exactly had been split.

So, what future splits should we be looking out for now? Local scientists are constantly undertaking research on our resident birds and those which we should be watching out for include Black-rumped Button-quail into Black-rumped and Hottentot Button-quail, Rufous-bellied Tit into Rufous-bellied and Cinnamon-bellied Tit, Sabota Lark into Sabota and Bradfield's Lark, Clapper Lark into Cape, Agulhas and Eastern Clapper Larks, Short-toed Rock Thrush into Short-toed and Pretoria Rock Thrush and Black-headed Canary into Black-headed and Damara Canary. And there's more…

Cape White-eye might well become Cape, Green and Orange River White-eyes, Olive Thrush could be Cape and Namaqua Thrush, Black-backed Cisticola should become Black-backed and Rufous-winged Cisticola, Pale-crowned Cisticola might be split into Pale-crowned and Wetland Cisticola, Grey-headed Sparrow will probably be Southern and Northern Grey-headed Sparrow and Crested Francolin could go to Crested and Kirk's Francolin.

Indian Yellow-nosed Albatross. Copyright: Trevor Hardaker

Indian Yellow-nosed Albatross. Copyright: Trevor Hardaker

On the international scene, similar research is being undertaken and many of the birds that visit us could also be representing more than one species. Of local interest might be Southern and Northern Royal Albatross, Wandering and Tristan Albatross, Atlantic and Indian Yellow-nosed Albatross, Subantarctic and Brown Skua and Cory's and Scopoli's Shearwater. And that's just the pelagic species…

What about the huge mess that the gulls are in? There will be Lesser Black-backed, Baltic and Heuglin's Gull as well as Herring and Armenian Gull. And then, of course, there is the Yellow Wagtail, that some authorities consider to be 12 separate species!!

So, there is still a lot of work to be done in this field. Watch this site for more updates.

.....Click here for the latest accepted list of all
Southern Africa's recorded species
(including all the latest splits).