WIWO-reports published

WIWO home

Publication number 56. Stichting WIWO

Title:	European Swallows Hirundo rustica in Botswana
Author(s):	Van den Brink B., R.G. Bijlsma & T.M. van der Have (eds.)
Publication date:	1998

Summary

The objectives of the Botswana Swallow Project 1993-95 were:

to collect information about the origin of European Swallows 'wintering' in Botswana, especially those from The Netherlands and other parts of Western Europe (where the species is in serious decline);
to assess the importance of Botswana as 'wintering' ground for European Swallows;
to study environmental factors that influence moult and body condition of European Swallows 'wintering' in Botswana;
to obtain information about site fidelity of Swallows to 'wintering' areas;
to study differences in the timing of moult of adult and juvenile European Swallows;
to count the number of waterbirds in wetlands used by European Swallows as roosting and foraging sites;
to investigate possible threats to European Swallow roost sites.

The report contains the final result of three Swallow expeditons to Botswana in the years 1992/93, 1993/94 and 1994/95. Three roosting sites were discovered, i.e. at the Gaborone Dam (up to 50,000), at the Shashe Dam (up to 5,000) and along the Boteti River near Maun (up to 3,000,000 in January 1994). All these sites were characterised by the presence of reedbeds in standing water. The importance of the Okavango Delta as a wintering site is not known.
Overall, numbers of European Swallows were very high in 1993/94, hig in 1992/93 and very small in 1994/95. These figures were correlated with rainfall patterns, with lowest numbers in years of drought. The proportion of juveniles was highest in 1993/94, and lowest in 1994/95 at all three study sites.

The report contains:

Methodology of trapping, handling and counting
The effects of rainfall on roosting behaviour, age ratios, body condition and speed of moult
Other avifaunistic observations
Appendices with maps and biometrics