Les G Underhill and Michael Brooks
Avian Demography Unit, University of Cape Town, Rondebosch 7701, South
Africa
les.underhill@uct.ac.za
Data collection for the Southern African Bird Atlas Project took place
from 1987 to 1991. Checklists were submitted throughout the year for 3000
quarter degree grid cells in the six countries of southern Africa: Botswana,
Lesotho, Namibia, South Africa, Swaziland and Zimbabwe. For each grid cell, the
reporting rate for a species consisted of the percentage of checklists which
recorded the species as present. The data for Barn Swallows Hirundo rustica
have been split into 10-day periods, and combined across the five years of
fieldwork, to produce an animation, based on actual observations, which shows
the arrival, stay and departure of Barn Swallows across southern Africa.
Alternative graphical displays of the data are also presented. On southward
migration, the Barn Swallow arrives earliest in northern Zimbabwe, from early
September, and reaches southernmost South Africa about a month later. On
northward migration, departure is remarkably synchronous, with (apart from
breeding season vagrants) the last records being made in March throughout
southern Africa.




