The Marico sunbird (Cinnyris mariquensis) is very much a Zambezi bird. It is the commonest sunbird in the Zambezi Valley, not found very much to the north, until you get to the Tanzanian border right up in the north, where it reappears. It does not occur in Lusaka, for example. In other words for some reason it does not like miombo, which is the dominant sort of vegetation covering most of the country.
The interesting thing is that there are a number of birds with this type of distribution, a reflection of the dry thornbush vegetation found south of the Zambezi in Botswana and Namibia, but starting again in the East African rift valley system, leaving the Central African moist miombo dominated belt of savannah woodlands of Zambia in between.
Prime examples are the kori bustard and the ostrich. Kori bustards are common as soon as you cross the Zambezi into Botswana (in fact it has on a few occasions been observed crossing over). Ostriches cannot of course cross the river but they are to be found not far south, and again in Tanzania close to the border.
The white–crowned shrike is another such bird although the ones north of the border differ slightly and are usually treated as a different species.
Among mammals, the bat-eared fox, the dik-dik, and the black-backed jackal are animals with this type of distribution, and they are unrecorded in Zambia.
The giraffe is an obvious case, but most interesting because there is an isolated endemic population, Thornicroft’s Giraffe, in the Luangwa Valley. This has been separated from those to the north, Masai Giraffe, and those to the south, Southern Giraffe, for long enough for them to have evolved into a distinct race.
So, back to the sunbirds. Most sunbirds have males which have patches of bright, often shiny metallic, colours; yellow, red, and blue with varying admixtures of green and violet iridescence. The females and immatures are usually dull greenish and indistinguishable. They all have long decurved beaks, used for sucking nectar from flowers. They are thus parallel to the humming birds of the New World, which are unrelated. However, they do also feed on insects which form their main source of sustenance.
They are not fussy about the flowers they choose, yet they are very selective about the general habitat. For instance at Katombora there are Marico Sunbirds in the Acacia trees by the river, but in the Teak forest up the hill they are replaced by purple banded sunbirds, which are very similar, green birds with a patch of colour on the breast, purple in the purple banded, red in the Marico. Voice is not very helpful for sunbirds – in this case they both have the same squeaky chittery calls.
Read more articles from this issue:
Zambezi Traveller (Issue 07, Dec 2011)